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MICROBIOLOGY (255 journals)                  1 2 | Last

Showing 1 - 200 of 255 Journals sorted alphabetically
Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Neurobiologiae Experimentalis     Open Access  
Addiction Genetics     Open Access   (Followers: 5)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22)
Advances in Microbiology     Open Access   (Followers: 23)
Advances in Molecular Imaging     Open Access   (Followers: 1)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Microbiology Research     Open Access   (Followers: 2)
Algorithms for Molecular Biology     Open Access   (Followers: 4)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 21)
American Journal of Microbiological Research     Open Access   (Followers: 2)
American Journal of Microbiology     Open Access   (Followers: 16)
American Journal of Molecular Biology     Open Access   (Followers: 3)
American Journal of Stem Cell Research     Open Access   (Followers: 4)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 8)
Annals of Microbiology     Hybrid Journal   (Followers: 10)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 39)
Antimicrobial Agents and Chemotherapy     Hybrid Journal   (Followers: 22)
Antiviral Research     Hybrid Journal   (Followers: 7)
Applied and Environmental Microbiology     Hybrid Journal   (Followers: 44)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 17)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 62)
Aquatic Microbial Ecology     Hybrid Journal   (Followers: 3)
Archives of Microbiology     Hybrid Journal   (Followers: 8)
Avicenna Journal of Clinical Microbiology and Infection     Open Access   (Followers: 2)
Bangladesh Journal of Medical Microbiology     Open Access   (Followers: 2)
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
Bio-Research     Full-text available via subscription   (Followers: 2)
BioArchitecture     Full-text available via subscription  
Bioethanol     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 9)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Biomolecular Detection and Quantification     Open Access  
Biomolecules     Open Access   (Followers: 2)
Biotechnology and Molecular Biology Reviews     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 11)
Brazilian Journal of Microbiology     Open Access   (Followers: 3)
Canadian Journal of Infectious Diseases and Medical Microbiology     Open Access   (Followers: 4)
Canadian Journal of Microbiology     Hybrid Journal   (Followers: 5)
Cell Biology : Research & Therapy     Hybrid Journal   (Followers: 5)
Cell Host & Microbe     Full-text available via subscription   (Followers: 19)
Cell Medicine     Open Access   (Followers: 5)
Cell Regeneration     Open Access   (Followers: 1)
Cell Stem Cell     Full-text available via subscription   (Followers: 34)
CellBio     Open Access  
Cells     Open Access   (Followers: 2)
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 13)
Cellular and Molecular Biology Letters     Open Access   (Followers: 1)
Cellular and Molecular Life Sciences (CMLS)     Hybrid Journal   (Followers: 5)
Cellular Microbiology     Hybrid Journal   (Followers: 9)
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (Followers: 2)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (Followers: 19)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 8)
Clinical Microbiology Reviews     Hybrid Journal   (Followers: 17)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 11)
Computational Molecular Bioscience     Open Access   (Followers: 2)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 12)
Current Clinical Microbiology Reports     Hybrid Journal   (Followers: 2)
Current Issues in Molecular Biology     Open Access   (Followers: 3)
Current Microbiology     Hybrid Journal   (Followers: 12)
Current Molecular Biology Reports     Hybrid Journal   (Followers: 1)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 32)
Current Tissue Engineering     Hybrid Journal   (Followers: 2)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 12)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 8)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (Followers: 3)
Environmental Microbiology     Hybrid Journal   (Followers: 16)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 5)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 13)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 5)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 18)
European Journal of Microbiology and Immunology     Open Access   (Followers: 9)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 4)
Experimental Cell Research     Hybrid Journal   (Followers: 5)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 8)
Fems Microbiology Letters     Hybrid Journal   (Followers: 20)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 25)
Fermentation     Open Access   (Followers: 1)
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 17)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 5)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 3)
Frontiers in Cellular Neuroscience     Open Access   (Followers: 8)
Frontiers in Microbiology     Open Access   (Followers: 12)
Frontiers in Molecular Neuroscience     Open Access   (Followers: 5)
Future Microbiology     Hybrid Journal   (Followers: 4)
Future Virology     Hybrid Journal   (Followers: 8)
Gene Expression     Full-text available via subscription  
Genetics and Molecular Research     Open Access   (Followers: 4)
Geomicrobiology Journal     Hybrid Journal   (Followers: 3)
Gut Microbes     Full-text available via subscription   (Followers: 8)
IAWA Journal     Hybrid Journal   (Followers: 1)
Indian Journal of Microbiology     Hybrid Journal   (Followers: 2)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 5)
Inside the Cell     Open Access  
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 7)
International Journal of Bacteriology     Open Access  
International Journal of Bioassays     Open Access   (Followers: 2)
International Journal of Biotechnology and Molecular Biology Research     Open Access   (Followers: 2)
International Journal of Food Microbiology     Hybrid Journal   (Followers: 13)
International Journal of Genetics and Molecular Biology     Open Access  
International Journal of Infection and Microbiology     Open Access   (Followers: 1)
International Journal of Medical Microbiology     Hybrid Journal   (Followers: 8)
International Journal of Molecular Medicine     Full-text available via subscription   (Followers: 5)
International Journal of Mycobacteriology     Open Access  
International Journal of Systematic and Evolutionary Microbiology     Full-text available via subscription   (Followers: 4)
International Journal of Virology and Molecular Biology     Open Access  
International Microbiology     Open Access   (Followers: 4)
Invertebrate Immunity     Open Access   (Followers: 1)
JMM Case Reports     Open Access  
Journal of Cell Science & Therapy     Open Access   (Followers: 2)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 2)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 2)
Journal of Applied Microbiology     Hybrid Journal   (Followers: 15)
Journal of Bacteriology     Hybrid Journal   (Followers: 29)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 3)
Journal of Biochemistry and Molecular Biology Research     Open Access  
Journal of Biomolecular Structure and Dynamics     Hybrid Journal   (Followers: 2)
Journal of Bionanoscience     Full-text available via subscription  
Journal of Bone Marrow Research     Open Access   (Followers: 2)
Journal of Brewing and Distilling     Open Access   (Followers: 2)
Journal of Cell and Animal Biology     Open Access  
Journal of Cell Biology and Genetics     Open Access   (Followers: 2)
Journal of Clinical Microbiology     Hybrid Journal   (Followers: 30)
Journal of Clinical Pathology     Full-text available via subscription   (Followers: 10)
Journal of Extracellular Vesicles     Open Access   (Followers: 4)
Journal of Food Microbiology     Open Access   (Followers: 5)
Journal of General and Molecular Virology     Open Access   (Followers: 1)
Journal of Genes and Cells     Open Access  
Journal of Global Antimicrobial Resistance     Hybrid Journal   (Followers: 2)
Journal of Industrial Microbiology and Biotechnology     Hybrid Journal   (Followers: 16)
Journal of Medical Microbiology     Full-text available via subscription   (Followers: 5)
Journal of Microbiological Methods     Hybrid Journal   (Followers: 3)
Journal of Microbiology     Hybrid Journal   (Followers: 8)
Journal of Microbiology and Antimicrobials     Open Access   (Followers: 2)
Journal of Microbiology Research     Open Access   (Followers: 5)
Journal of Micropalaeontology     Hybrid Journal   (Followers: 7)
Journal of Molecular Biochemistry     Open Access   (Followers: 3)
Journal of Molecular Biology Research     Open Access   (Followers: 3)
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 14)
Journal of Molecular Psychiatry     Open Access   (Followers: 9)
Journal of Morphology     Hybrid Journal   (Followers: 5)
Journal of Pharmacy & Bioresources     Full-text available via subscription   (Followers: 2)
Journal of Plant Pathology & Microbiology     Open Access   (Followers: 1)
Journal of Proteome Science and Computational Biology     Open Access  
Journal of Regenerative Medicine and Tissue Engineering     Open Access   (Followers: 4)
Journal of The Academy of Clinical Microbiologists     Open Access  
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 2)
Journal of the Institute of Brewing     Free   (Followers: 3)
Journal of Tropical Microbiology and Biotechnology     Full-text available via subscription  
Jundishapur Journal of Microbiology     Open Access  
Letters In Applied Microbiology     Hybrid Journal   (Followers: 7)
Macrophage     Open Access  
MAP Kinase     Open Access  
Medical Mycology     Open Access   (Followers: 4)
Memórias do Instituto Oswaldo Cruz     Open Access  
Methods in Molecular Biology     Hybrid Journal   (Followers: 18)
Microbes and Health     Open Access   (Followers: 1)
Microbes and Infection     Full-text available via subscription   (Followers: 5)
Microbial Biotechnology     Open Access   (Followers: 9)
Microbial Cell Factories     Open Access   (Followers: 6)
Microbial Drug Resistance     Hybrid Journal   (Followers: 4)
Microbial Ecology     Hybrid Journal   (Followers: 10)
Microbial Ecology in Health and Disease     Open Access  
Microbial Informatics and Experimentation     Open Access   (Followers: 1)
Microbial Pathogenesis     Hybrid Journal   (Followers: 7)
Microbial Risk Analysis     Full-text available via subscription  
Microbiologia Medica     Open Access   (Followers: 1)
Microbiological Research     Hybrid Journal   (Followers: 6)
Microbiology     Hybrid Journal   (Followers: 14)
Microbiology (SGM)     Full-text available via subscription   (Followers: 18)
Microbiology and Immunology     Hybrid Journal   (Followers: 10)
Microbiology and Molecular Biology Reviews     Hybrid Journal   (Followers: 25)
Microbiology Australia     Hybrid Journal  
Microbiology Discovery     Open Access   (Followers: 2)
Microbiology Indonesia     Open Access  
Microbiology Research     Open Access   (Followers: 7)
MicrobiologyOpen     Open Access   (Followers: 2)
Microbiome     Hybrid Journal   (Followers: 8)
Microbiome Science and Medicine     Open Access   (Followers: 2)
Microorganisms     Open Access   (Followers: 2)
MicroRNA     Hybrid Journal   (Followers: 1)
Molecular and Cellular Therapies     Open Access  
Molecular Biology and Genetic Engineering     Open Access   (Followers: 1)
Molecular Biology Research Communications     Open Access   (Followers: 1)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 3)
Molecular Genetics, Microbiology and Virology     Hybrid Journal   (Followers: 7)
Molecular Imaging     Open Access  
Molecular Imaging and Biology     Hybrid Journal   (Followers: 2)
Molecular Medicine     Open Access   (Followers: 3)
Molecular Medicine Reports     Full-text available via subscription   (Followers: 4)
Molecular Microbiology     Hybrid Journal   (Followers: 32)
Molecular Oral Microbiology     Partially Free   (Followers: 3)
Molecular Systems Biology     Open Access   (Followers: 11)

        1 2 | Last

Journal Cover International Journal of Food Microbiology
  [SJR: 1.64]   [H-I: 142]   [13 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0168-1605
   Published by Elsevier Homepage  [3043 journals]
  • Plant-mediated restriction of Salmonella enterica on tomato and spinach
           leaves colonized with Pseudomonas plant growth-promoting rhizobacteria
    • Authors: Chiun-Kang Hsu; Shirley A. Micallef
      Pages: 1 - 6
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): Chiun-Kang Hsu, Shirley A. Micallef
      Reducing Salmonella enterica association with plants during crop production could reduce risks of fresh produce-borne salmonellosis. Plant growth-promoting rhizobacteria (PGPR) colonizing plant roots are capable of promoting plant growth and boosting resistance to disease, but the effects of PGPR on human pathogen-plant associations are not known. Two root-colonizing Pseudomonas strains S2 and S4 were investigated in spinach, lettuce and tomato for their plant growth-promoting properties and their influence on leaf populations of S. enterica serovar Newport. Plant roots were inoculated with Pseudomonas in the seedling stage. At four (tomato) and six (spinach and lettuce) weeks post-germination, plant growth promotion was assessed by shoot dry weight (SDW) and leaf chlorophyll content measurements. Leaf populations of S. Newport were measured after 24h of leaf inoculation with this pathogen by direct plate counts on Tryptic Soy Agar. Root inoculation of spinach cv. ‘Tyee’, with Pseudomonas strain S2 or S4 resulted in a 69% and 63% increase in SDW compared to non-inoculated controls (p <0.005 and p <0.01, respectively). Similarly, Romaine lettuce cv. ‘Parris Island Cos’ responded positively to S2 and S4 inoculation (53% and 48% SDW increase, respectively; p <0.05), and an increase in leaf chlorophyll content (p <0.001), compared to controls. Tomato cv. ‘Nyagous’ yielded significantly greater SDW (74%, p <0.01 and 54%, p <0.05 for S2 and S4, respectively), and also higher leaf chlorophyll content (19% and 29%, p <0.001, respectively) relative to controls. Leaf chlorophyll content only increased in S4-inoculated tomato cv. ‘Moneymaker’ plants (27%, p <0.001), although both S2 and S4 promoted plant growth by over 40% compared to controls (p <0.01 and p <0.05, respectively). No significant growth promotion was detected in tomato cv. ‘BHN602’, but S2-inoculated plants had elevated leaf chlorophyll content (13%, p <0.01). Root inoculation with Pseudomonas S4 restricted S. Newport populations inoculated on leaves of spinach (p <0.001) and all three tomato cultivars (p <0.05), compared to controls, 24h post Salmonella inoculation. Impairment of S. Newport leaf populations was also observed on spinach when plant roots were inoculated with S2 (p <0.01). With an initial leaf inoculum of approximately 6.0logCFU of S. Newport/plant, the significantly greater reduction of S. Newport populations on Pseudomonas-treated plants than those on non-inoculated control plants after 24h was modest with differences of one log or less. By contrast, the survival of S. Newport on the leaves of Romaine lettuce was not influenced by Pseudomonas root colonization. These findings provide evidence that root inoculation of certain specialty crops with beneficial Pseudomonas strains exhibiting PGPR properties may not only promote plant growth, but also reduce the fitness of epiphytic S. enterica in the phyllosphere. Plant-mediated effects induced by PGPR may be an effective strategy to minimize contamination of crops with S. enterica during cultivation.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.012
      Issue No: Vol. 259 (2017)
  • Torulaspora delbrueckii contribution in mixed brewing fermentations with
           different Saccharomyces cerevisiae strains
    • Authors: Laura Canonico; Francesca Comitini; Maurizio Ciani
      Pages: 7 - 13
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): Laura Canonico, Francesca Comitini, Maurizio Ciani
      In recent years, there has been growing demand for distinctive high quality beer. Fermentation management has a fundamental role in beer quality and the levels of aroma compounds. Use of non-conventional yeast has been proposed to enhance beer bioflavor. In the present work we investigated mixed fermentations using three commercial Saccharomyces cerevisiae strains, without and with addition of a selected Torulaspora delbrueckii strain evaluating their interactions, as well as the aroma profiles. At the S. cerevisiae/T. delbrueckii co-inoculation ratio of 1:20, viable cell counts indicated that T. delbrueckii dominated all of the three combinations. In the mixed fermentations, T. delbrueckii provided higher levels of higher alcohols (excepting of β-phenyl ethanol), in contrast to data obtained in winemaking, where higher alcohols had lower levels. Moreover, mixed fermentations showed significantly higher ethyl acetate (from 5 to 16mg/L) and isoamyl acetate (from 0.019 to 0.128mg/L), and were generally lower in ethyl hexanoate and ethyl octanoate. Therefore, irrespective of S. cerevisiae strain, T. delbrueckii influenced on all mixed fermentations. On the other hand, the mixed fermentations were also affected by each of the three S. cerevisiae strains, which resulted in beers with distinctive flavors.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.017
      Issue No: Vol. 259 (2017)
  • Comparison of the fate of the top six non-O157 shiga-toxin producing
           Escherichia coli (STEC) and E. coli O157:H7 during the manufacture of dry
           fermented sausages
    • Authors: S. Balamurugan; Rafath Ahmed; Anli Gao; Phil Strange
      Pages: 14 - 21
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): S. Balamurugan, Rafath Ahmed, Anli Gao, Phil Strange
      The study examined the relative fate of the top six non-O157 shiga-toxin producing Escherichia coli (STEC) and E. coli O157:H7 during the manufacture of dry fermented sausages (DFS). Three separate batches of sausages containing a five-strain cocktail for each serogroup and uninoculated control were manufactured and subjected to identical fermentation, maturation and dry curing conditions. Changes in physicochemical properties and inoculated STEC numbers were enumerated during the DFS production stages and log reduction and log reduction rates were calculated. Inoculation of very high concentrations (8logCFUg−1) of STEC in the sausage batter did not significantly (P >0.05) affect the changes in the pH, aw, moisture, protein, fat content compared to the uninoculated DFS. There was a significant (P <0.05) reduction in counts within the 48h fermentation for all STEC serogroups inoculated by about 0.97- to 1.42-log units. However, during the sausage maturation stage, all serogroups except O121 and O45 showed a significant reduction in numbers. During the extended 34day drying stage, all STEC serogroups showed a significant reduction in counts reaching a 5-log reduction within 20 to 27days of drying. ANOVA of the log reduction rates revealed significant differences in the reduction rates among the STEC serogroups examined. During the fermentation stage, serogroup O45 had the highest reduction rate at 0.98-logCFUg−1 day−1 which was significantly higher compared to all other STEC serogroups (P <0.05), while O26 was the most tolerant to the conditions encountered during the fermentation stage with a reduction rate of 0.49-logCFUg−1 day−1. However, during the extended 34days drying stage all STEC serogroups showed a steady reduction in population with a reduction rate ranging from 0.11- to 0.18-logCFUg−1 day−1. The log reduction rate of E. coli O157:H7 was similar to that of serogroups O111 and O103, but was significantly lower (P <0.05) than all other STEC serogroups examined in the study. The log reduction rates of serogroups O121, O45, O145 and O26 during drying were not significantly different (P >0.05) from each other. These results indicate that the lethality of DFS production processes observed against E. coli O157:H7 would result in a similar inactivation of the top six non-O157 STEC.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.018
      Issue No: Vol. 259 (2017)
  • Differentiation and identification of grape-associated black aspergilli
           using Fourier transform infrared (FT-IR) spectroscopic analysis of mycelia
    • Authors: Efstathia A. Kogkaki; Manos Sofoulis; Pantelis Natskoulis; Petros A. Tarantilis; Christos S. Pappas; Efstathios Z. Panagou
      Pages: 22 - 28
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): Efstathia A. Kogkaki, Manos Sofoulis, Pantelis Natskoulis, Petros A. Tarantilis, Christos S. Pappas, Efstathios Z. Panagou
      The purpose of this study was to evaluate the potential of FT-IR spectroscopy as a high-throughput method for rapid differentiation among the ochratoxigenic species of Aspergillus carbonarius and the non-ochratoxigenic or low toxigenic species of Aspergillus niger aggregate, namely A. tubingensis and A. niger isolated previously from grapes of Greek vineyards. A total of 182 isolates of A. carbonarius, A. tubingensis, and A. niger were analyzed using FT-IR spectroscopy. The first derivative of specific spectral regions (3002–2801cm−1, 1773–1550cm−1, and 1286–952cm−1) were chosen and evaluated with respect to absorbance values. The average spectra of 130 fungal isolates were used for model calibration based on Discriminant analysis and the remaining 52 spectra were used for external model validation. This methodology was able to differentiate correctly 98.8% in total accuracy in both model calibration and validation. The per class accuracy for A. carbonarius was 95.3% and 100% for model calibration and validation, respectively, whereas for A. niger aggregate the per class accuracy amounted to 100% in both cases. The obtained results indicated that FT-IR could become a promising, fast, reliable and low-cost tool for the discrimination and differentiation of closely related fungal species.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.020
      Issue No: Vol. 259 (2017)
  • Frequency of hepatitis E virus, rotavirus and porcine enteric calicivirus
           at various stages of pork carcass processing in two pork processing plants
    • Authors: Tineke H. Jones; Victoria Muehlhauser
      Pages: 29 - 34
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): Tineke H. Jones, Victoria Muehlhauser
      Hepatitis E virus (HEV), rotavirus (RV), and porcine enteric calicivirus (PEC) infections are common in swine and raises concerns about the potential for zoonotic transmission through undercooked meat products. Enteric viruses can potentially contaminate carcasses during meat processing operations. There is a lack of information on the prevalence and control of enteric viruses in the pork processing chain. This study compared the incidence and levels of contamination of hog carcasses with HEV, RV and PEC at different stages of the dressing process. A total of 1000 swabs were collected from 2 pork processing plants on 10 separate occasions over the span of a year. The samples were obtained from random sites on hog carcasses at 4 dressing stages (plant A: bleeding, dehairing, pasteurization, and evisceration; plant B: bleeding, skinning, evisceration, and washing) and from meat cuts. Numbers of genome copies (gc) of HEV, RV and PEC were determined by RT-qPCR. RV and PEC were detected in 100%, and 18% of samples, respectively, after bleeding for plant A and in 98%, and 36% of samples, respectively, after bleeding for plant B. After evisceration, RV and PEC were detected in 21% and 3% of samples, respectively, for plant A and in 1%, and 0% of samples, respectively for plant B. RV and PEC were detected on 1%, and 5% of pork cuts, respectively, for plant A and on 0%, and 0% of pork cuts, respectively, for plant B. HEV was not detected in any pork carcass or retail pork samples from plants A or B. The frequency of PEC and RV on pork is progressively reduced along the pork processing chain but the viruses were not completely eliminated. The findings suggest that consumers could be at risk when consuming undercooked meat contaminated with pathogenic enteric viruses.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.019
      Issue No: Vol. 259 (2017)
  • The individual contribution of starter and non-starter lactic acid
           bacteria to the volatile organic compound composition of Caciocavallo
           Palermitano cheese
    • Authors: Valeria Guarrasi; Ciro Sannino; Marta Moschetti; Adriana Bonanno; Antonino Di Grigoli; Luca Settanni
      Pages: 35 - 42
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): Valeria Guarrasi, Ciro Sannino, Marta Moschetti, Adriana Bonanno, Antonino Di Grigoli, Luca Settanni
      The contribution of two starter (Lactobacillus delbrueckii and Streptococcus thermophilus) and nine non-starter (Enterococcus casselliflavus, Enterococcus faecalis, Enterococcus durans, Enterococcus gallinarum, Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, Pediococcus acidilactici and Pediococcus pentosaceus) species of lactic acid bacteria (LAB) to the volatile organic compounds (VOCs) of Caciocavallo Palermitano cheese was investigated. The strains used in this study were isolated during the production/ripening of the stretched cheese and tested in a cheese-based medium (CBM). The fermented substrates were analyzed for the growth of the single strains and subjected to the head space solid phase micro-extraction (HS-SPME) and gas chromatography – mass spectrometry (GC–MS). The 11 strains tested were all able to increase their numbers in CBM, even though the development of the starter LAB was quite limited. GC–MS analysis registered 43 compounds including seven chemical classes. A lower diversity of VOCs was registered for the unfermented curd based medium (CuBM) analyzed for comparison. The class of ketones represented a consistent percentage of the VOCs for almost all LAB, followed by alcohols and esters. The volatile profile of Pediococcus acidilactici and Lactobacillus delbrueckii was mainly characterized by 2-butanol, butanoic acid and hexanoic acid and their esters, while that of Lactobacillus casei and Lactobacillus rhamnosus was characterized by 2,3-butanedione and 2-butanone, 3-hydroxy. In order to correlate the VOCs produced by Caciocavallo Palermitano cheeses with those generated by individual LAB, the 4-month ripened cheeses resulting from the dairy process monitored during the isolation of LAB were also analyzed for the volatile chemical fraction and the compounds in common were subjected to a multivariate statistical analysis. The canonical analysis indicated that the VOCs of the ripened cheeses were mainly influenced by E. gallinarum, L. paracasei, L. delbrueckii, L. rhamnosus and L. casei and that 1-hexanol, o-xylene and m-xylene were the cheese VOCs highly correlated with LAB.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.022
      Issue No: Vol. 259 (2017)
  • Antimicrobial resistance and resistance genes in Salmonella strains
           isolated from broiler chickens along the slaughtering process in China
    • Authors: Yuanting Zhu; Haimei Lai; Likou Zou; Sheng Yin; Chengtao Wang; Xinfeng Han; Xiaolong Xia; Kaidi Hu; Li He; Kang Zhou; Shujuan Chen; Xiaolin Ao; Shuliang Liu
      Pages: 43 - 51
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): Yuanting Zhu, Haimei Lai, Likou Zou, Sheng Yin, Chengtao Wang, Xinfeng Han, Xiaolong Xia, Kaidi Hu, Li He, Kang Zhou, Shujuan Chen, Xiaolin Ao, Shuliang Liu
      A total of 189 Salmonella isolates were recovered from 627 samples which were collected from cecal contents of broilers, chicken carcasses, chicken meat after cutting step and frozen broiler chicken products along the slaughtering process at a slaughterhouse in Sichuan province of China. The Salmonella isolates were subjected to antimicrobial susceptibility testing to 10 categories of antimicrobial agents using the Kirby–Bauer disk diffusion method. Those antibiotics-resistant isolates were further investigated for the occurrence of resistance genes, the presence of class 1 integron as well as the associated gene cassettes, and the mutations within the gyrA and parC genes. Consequently, the prevalence of Salmonella was 30.14% (47.96% for cecal content, 18.78% for chicken carcasses, 31.33% for cutting meat and 14.00% for frozen meat, respectively). The predominant serotypes were S. Typhimurium (15.34%) and S. Enteritidis (69.84%). High resistance rates to the following drugs were observed: nalidixic acid (99.5%), ampicillin (87.8%), tetracycline (51.9%), ciprofloxacin (48.7%), trimethoprim/sulfamethoxazole (48.1%), and spectinomycin (34.4%). Antimicrobial resistance profiling showed that 60.8% of isolates were multidrug resistant (MDR), and MDR strains increased from 44.7% to 78.6% along the slaughtering line. 94.6% (n =157) of beta-lactam-resistant isolates harbored at least one resistance gene of bla TEM or bla CTX-M. The relatively low prevalence of aminoglycoside resistance genes (aac(3)-II, aac(3)-IV, and ant(2″)-I) was found in 49 (66.2%) of antibiotic-resistant isolates. The tetracycline resistance genes (tet(A), tet(B), tet(C), and tet(G) and sulfonamide resistance genes (sul1, sul2, and sul3) were identified in 84 (85.7%) and 89 (97.8%) antibiotic-resistant isolates respectively. floR was identified in 44 (97.8%) florfenicol-resistant isolates. Class 1 integron was detected in 37.4% (n =43) of the MDR isolates. Two different gene cassettes, bla OXA-30-aadA1 (19 isolates) and bla OXA-30 -aadA1/drfA1-orfC (2 isolates), were identified in class 1 integron-positive isolates. 97.9% (184/188) of quinolone-resistant isolates had at least one mutation within gyrA or parC. Overall, antimicrobial resistance showed an increasing trend along the slaughtering process. The results showed that broiler chicken products in the slaughterhouse were contaminated with MDR Salmonella, which might originate from food producing animals to some extent, and cross-contamination during slaughter, and facilitate the dissemination of the resistance genes to consumers along the production chain, which suggests importance of controlling Salmonella during slaughter for public health, underlying strict hygiene method and HACCP management to reduce cross-contamination.

      PubDate: 2017-08-17T10:24:40Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.023
      Issue No: Vol. 259 (2017)
  • Sequential transition of the injury phenotype, temperature-dependent
           survival and transcriptional response in Listeria monocytogenes following
           lethal H2O2 exposure
    • Authors: Yoshitsugu Ochiai; Fumiya Yamada; Yuko Yoshikawa; Mariko Mochizuki; Takashi Takano; Ryo Hondo; Fukiko Ueda
      Pages: 52 - 58
      Abstract: Publication date: 16 October 2017
      Source:International Journal of Food Microbiology, Volume 259
      Author(s): Yoshitsugu Ochiai, Fumiya Yamada, Yuko Yoshikawa, Mariko Mochizuki, Takashi Takano, Ryo Hondo, Fukiko Ueda
      The food-borne pathogen Listeria monocytogenes is present persistently in food processing environments, where this bacterium is exposed to various stress factors, including oxidative stress. This study aimed to elucidate the temperature-dependent response of L. monocytogenes to H2O2 exposure and the phenotypic changes in colony formation by H2O2-treated bacteria. Survival curves indicated an increase in the resistance to H2O2 in L. monocytogenes as the temperature decreased during the stress exposure procedure. Transcriptional induction of genes with key roles in response to H2O2, including sigB and kat, was observed at 37°C, but not at 20°C, whereas other stress response genes were induced at both temperatures. Following H2O2 exposure, L. monocytogenes produced small colony phenotypes and the colony size decreased in a stress exposure duration-dependent manner. Resuscitated cells with no ability to form colonies in the absence of sodium pyruvate were also found. Our findings show the possibility that a sequential transition in the injury phenotype from small colony phenotype to resuscitated cells occurred during the course of exposure to H2O2. The higher H2O2 resistance at 20°C than 37°C suggests further investigation of the response to H2O2 exposure under the lower temperatures, including refrigeration temperature, which may contribute to elucidation of bacterial survival over extended time periods in food-processing environments.

      PubDate: 2017-08-17T10:24:40Z
      DOI: 10.1016/j.ijfoodmicro.2017.08.001
      Issue No: Vol. 259 (2017)
  • The role of nitrogen uptake on the competition ability of three vineyard
           Saccharomyces cerevisiae strains
    • Authors: Chiara Vendramini; Gemma Beltran; Chiara Nadai; Alessio Giacomini; Albert Mas; Viviana Corich
      Pages: 1 - 11
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Chiara Vendramini, Gemma Beltran, Chiara Nadai, Alessio Giacomini, Albert Mas, Viviana Corich
      Three vineyard strains of Saccharomyces cerevisiae, P301.4, P304.4 and P254.12, were assayed in comparison with a commercial industrial strain, QA23. The aim was to understand if nitrogen availability could influence strain competition ability during must fermentation. Pairwise-strain fermentations and co-fermentations with the simultaneous presence of the four strains were performed in synthetic musts at two nitrogen levels: control nitrogen condition (CNC) that assured the suitable assimilable nitrogen amount required by the yeast strains to complete the fermentation and low nitrogen condition (LNC) where nitrogen is present at very low level. Results suggested a strong involvement of nitrogen availability, as the frequency in must of the vineyard strains, respect to QA23, in LNC was always higher than that found in CNC. Moreover, in CNC only strain P304.4 reached the same strain frequency as QA23. P304.4 competition ability increased during the fermentation, indicating better performance when nitrogen availability was dropping down. P301.4 was the only strain sensitive to QA23 killer toxin. In CNC, when it was co-inoculated with the industrial strain QA23, P301.4 was never detected. In LNC, P301.4 after 12h accounted for 10% of the total population. This percentage increased after 48h (20%). Single-strain fermentations were also run in both conditions and the nitrogen metabolism further analyzed. Fermentation kinetics, ammonium and amino-acid consumptions and the expression of genes under nitrogen catabolite repression evidenced that vineyard yeasts, and particularly strain P304.4, had higher nitrogen assimilation rate than the commercial control. In conclusion, the high nitrogen assimilation rate seems to be an additional strategy that allowed vineyard yeasts successful competition during the growth in grape musts.

      PubDate: 2017-07-21T12:25:18Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.006
      Issue No: Vol. 258 (2017)
  • Characterization and horizontal transfer of qacH-associated class 1
           integrons in Escherichia coli isolated from retail meats
    • Authors: Xiaobing Jiang; Yameng Xu; Yi Li; Kun Zhang; Lei Liu; Hailei Wang; Jinhe Tian; Hao Ying; Lei Shi; Tao Yu
      Pages: 12 - 17
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Xiaobing Jiang, Yameng Xu, Yi Li, Kun Zhang, Lei Liu, Hailei Wang, Jinhe Tian, Hao Ying, Lei Shi, Tao Yu
      The aim of this study was to examine the presence of genes responsible for resistance to quaternary ammonium compounds (QACs) and the association of qac genes with class 1 integrons in Escherichia coli isolated from retail meats. Among the 179 E. coli isolates tested, the minimum inhibitory concentrations (MICs) of benzalkonium chloride (BC) ranged from 4 to 64μg/mL. PCR assays indicated that QAC-resistance genes sugE(c), ydgE/ydgF, mdfA, emrE and qacEΔ1 were commonly present (40.2%–88.3%) in these isolates, but qacE, qacF, qacH and sugE(p) were less prevalent (2.2%–28.5%). Seven different gene cassette arrangements were identified in 31 intI1-positive isolates. Three types of qacH-sul3-associated non-classic integrons were observed in four isolates: dfrA12-orfF-aadA2-cmlA1-aadA1-qacH-IS440-sul3, aadA2-cmlA1-aadA1-qacH-IS440-sul3 and dfrA1-aadA1-qacH-IS440-sul3. Non-classic class 1 integrons were located on plasmids of 100–150kb in these four isolates. Our results demonstrated that the qacH-associated integrons located on 100 kb plasmids in two isolates could be transferred to an E. coli recipient, indicating the co-existence and co-dissemination of disinfectant and antimicrobial resistance genes among bacterial species.

      PubDate: 2017-07-28T08:29:19Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.009
      Issue No: Vol. 258 (2017)
  • Proteomic and genetics insights on the response of the bacteriocinogenic
           Lactobacillus sakei CRL1862 during biofilm formation on stainless steel
           surface at 10°C
    • Authors: Mariana Pérez-Ibarreche; Lucía M. Mendoza; Graciela Vignolo; Silvina Fadda
      Pages: 18 - 27
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Mariana Pérez-Ibarreche, Lucía M. Mendoza, Graciela Vignolo, Silvina Fadda
      Some lactic acid bacteria have the ability to form biofilms on food-industry surfaces and this property could be used to control food pathogens colonization. Lactobacillus sakei CR1862 was selected considering its bacteriocinogenic nature and ability to adhere to abiotic surfaces at low temperatures. In this study, the proteome of L. sakei CRL1862 grown either under biofilm on stainless steel surface and planktonic modes of growth at 10°C, was investigated. Using two-dimensional gel electrophoresis, 29 out of 43 statistically significant spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Ten proteins resulted up-regulated whereas 16 were down-regulated during biofilm formation. Differentially expressed proteins were found to belong to carbohydrate, nucleotide, aminoacid and lipid metabolisms as well as translation, peptide hydrolysis, cell envelope/cell wall biosynthesis, adaption to atypical conditions and protein secretion. Some proteins related to carbohydrate and nucleotide metabolisms, translation and peptide degradation were overexpressed whereas those associated to stress conditions were synthesized in lower amounts. It seems that conditions for biofilm development would not imply a stressful environment for L. sakei CRL1862 cells, directing its growth strategy towards glycolytic flux regulation and reinforcing protein synthesis. In addition, L. sakei CRL1862 showed to harbor nine out of ten assayed genes involved in biofilm formation and protein anchoring. By applying qRT-PCR analysis, four of these genes showed to be up regulated, srtA2 being the most remarkable. The results of this study contribute to the knowledge of the physiology of L. sakei CRL1862 growing in biofilm on a characteristic food contact surface. The use of this strain as green biocide preventing L. monocytogenes post-processing contamination on industrial surfaces may be considered.

      PubDate: 2017-07-28T08:29:19Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.003
      Issue No: Vol. 258 (2017)
  • Interaction of microorganisms within leafy green phyllospheres: Where do
           human noroviruses fit in'
    • Authors: Wenjun Deng; Kristen E. Gibson
      Pages: 28 - 37
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Wenjun Deng, Kristen E. Gibson
      Human noroviruses (hNoV) are one of the major causes of foodborne disease outbreaks linked to leafy greens. However, the interactions—including attachment and persistence—of hNoV with leafy greens are not well characterized. In the present review, three mechanisms are hypothesized for the interaction of hNoV with leafy green phyllospheres: 1) specific binding to histo-blood group antigen (HBGA)-like carbohydrates exposed on leaf surfaces and present on bacterial microbiota; 2) non-specific binding through electrostatic forces; and 3) internalization of hNoV through contaminated water (e.g. hydroponic feed water). To add more complexity, there is a rich diversity of microbial communities (i.e., bacteria, fungi, protozoa) residing in leafy green phyllospheres, and the attachment and persistence of hNoV could be largely impacted by these microorganisms through direct and indirect interactions. For instance, enzymes produced by bacteria and fungi could potentially compromise the structure of HBGA-like carbohydrate binding sites on leaves, leading to a reduction in hNoV binding. On the other hand, some bacteria also possess HBGA-like binding sites on their cell surface, which may provide extra binding locations for hNoV. There are also numerous metabolic compounds that can be produced by leafy greens and its microbial inhabitants and be subsequently distributed within leafy green phyllospheres. These compounds could theoretically play roles in enhancement or reduction in the attachment of hNoV. Overall, increasing the understanding of the various types of hNoV attachment and interactions with leafy green phyllospheres will be crucial for elucidating hNoV transmission via leafy greens as well as for the development of effective control measures.

      PubDate: 2017-07-28T08:29:19Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.010
      Issue No: Vol. 258 (2017)
  • Genetic diversity of Toxoplasma gondii isolates from ruminants: A
           systematic review
    • Authors: Mehdi Sharif; Afsaneh Amouei; Shahabeddin Sarvi; Azadeh Mizani; Mohsen Aarabi; Seyed-Abdollah Hosseini; Ahmad Daryani
      Pages: 38 - 49
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Mehdi Sharif, Afsaneh Amouei, Shahabeddin Sarvi, Azadeh Mizani, Mohsen Aarabi, Seyed-Abdollah Hosseini, Ahmad Daryani
      Toxoplasma gondii is a protozoan capable of infecting all warm-blooded animals. This parasite has been classified into three major lineages. Our aim was to assess and compare the identified Types and genotypes in ruminants. From November 2014 to April 2015, four English language databases and four Persian databases that reported data on the T. gondii genotyping in ruminants were searched. Overall, typing results of the 250/307 T. gondii isolates in all animals showed that Type II was a predominant Type (81.4%). In addition, genotyping data from the 82/215 T. gondii isolates or strains indicated that atypical genotypes were predominant (38.13%). This systematic review has demonstrated a large degree of genetic diversity in some countries. However, in the new nomenclature of genotyping, there are atypical or exotic genotypes, such as Chinese 1, Types Br (I, II, III and IV), and Type 12. Further genotyping studies are required to corroborate the current results.

      PubDate: 2017-07-28T08:29:19Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.007
      Issue No: Vol. 258 (2017)
  • Genotyping of Lactobacillus sanfranciscensis isolates from Chinese
           traditional sourdoughs by multilocus sequence typing and multiplex
    • Authors: Huanyi Yang; Tongjie Liu; Guohua Zhang; Jiancai Chen; Jingsi Gu; Lei Yuan; Guoqing He
      Pages: 50 - 57
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Huanyi Yang, Tongjie Liu, Guohua Zhang, Jiancai Chen, Jingsi Gu, Lei Yuan, Guoqing He
      Lactobacillus sanfranciscensis is the predominant lactic acid bacteria (LAB) species in Chinese traditional sourdoughs and conduces to the flavor and rheology properties of Chinese steamed bread, a staple food originated in China over 1500years ago. The aim of this study is to describe the intraspecific diversity of 98 L. sanfranciscensis isolates from 11 Chinese traditional sourdoughs in different regions by multilocus sequence typing (MLST) and multiplex random amplified polymorphic DNA-polymerase chain reaction (multiplex RAPD-PCR). MLST scheme was reduced from six gene fragments (gdh, gyrA, mapA, nox, pgmA and pta) to five (gdh, gyrA, mapA, nox and pta) since the fragment of pgmA displayed only one allele. 10 different sequence types (STs) were revealed by MLST and 6 of them containing 79.8% of the isolates were classified into one clonal complex, demonstrating a close relationship among them. The multiplex-RAPD analysis was performed by employing the combined primers OPL-05+RD1 and divided the 98 L. sanfranciscensis isolates into 6 types with the similarity level of 70%. According to the result, it seems that the genotypic variations of L. sanfranciscensis strains showed by MLST have no relations to geographical origin. MLST seems to have a higher discriminatory power compared with multiplex-RAPD since it produced more groups, but multiplex-RAPD could help to distinguish some strains in the same ST. Hence, an optimal genotypic characterization of L. sanfranciscensis was obtained under the combination of MLST and multiplex-RAPD analysis, targeting different genetic variations.

      PubDate: 2017-07-28T08:29:19Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.013
      Issue No: Vol. 258 (2017)
  • Inhibition of Salmonella by thyme essential oil and its effect on
           microbiological and sensory properties of minced pork meat packaged under
           vacuum and modified atmosphere
    • Authors: Marija Boskovic; Jasna Djordjevic; Jelena Ivanovic; Jelena Janjic; Nemanja Zdravkovic; Milica Glisic; Natasa Glamoclija; Branislav Baltic; Vesna Djordjevic; Milan Baltic
      Pages: 58 - 67
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Marija Boskovic, Jasna Djordjevic, Jelena Ivanovic, Jelena Janjic, Nemanja Zdravkovic, Milica Glisic, Natasa Glamoclija, Branislav Baltic, Vesna Djordjevic, Milan Baltic
      The antibacterial activity of thyme essential oil (TEO) was evaluated against four serovars of Salmonella (S. Enteritidis, S. Typhimurium, S. Montevideo and S. Infantis), experimentally inoculated (106 CFU/g) in minced pork, which was treated with different concentrations of the TEO (0.3%, 0.6% and 0.9%) packaged under vacuum or MAP (30%O2/50%CO2/20% N2) and stored at 3±1°C for 15days. GC–MS analysis of the TEO was performed in order to determine composition, and the predominant constituent was thymol (50.48%), followed by p-cymene and linalool. The minimum inhibitory concentration was determined for each Salmonella serovar studied. Among the tested active compounds, thymol and carvacrol exhibited the greatest inhibitory effect followed by TEO, with minimum inhibitory concentrations of 320 to 640μg/ml. S. Enteritidis was the most sensitive serovar. During the storage period, Salmonella counts in pork were reduced by 1.69–4.05logCFU/g. The influence of TEO on Enterobacteriaceae, lactic acid bacteria and total viable count was determined in control mince with no added Salmonella. The most pronounced antibacterial effect was achieved by the combination MAP and 0.9% TEO. Although the antibacterial activities of all studied concentrations of TEO in pork were evident and significant (P <0.05), sensory analysis showed that 0.3% TEO was the most acceptable to trained panellists.

      PubDate: 2017-07-28T08:29:19Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.011
      Issue No: Vol. 258 (2017)
  • Survival of selected foodborne pathogens on dry cured pork loins
    • Authors: Ángela M. Morales-Partera; Fernando Cardoso-Toset; Francisco Jurado-Martos; Rafael J. Astorga; Belén Huerta; Inmaculada Luque; Carmen Tarradas; Jaime Gómez-Laguna
      Pages: 68 - 72
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Ángela M. Morales-Partera, Fernando Cardoso-Toset, Francisco Jurado-Martos, Rafael J. Astorga, Belén Huerta, Inmaculada Luque, Carmen Tarradas, Jaime Gómez-Laguna
      The safety of ready-to-eat products such as cured pork loins must be guaranteed by the food industry. In the present study, the efficacy of the dry curing process of pork loins obtained from free-range pigs in the reduction of three of the most important foodborne pathogens is analysed. A total of 28 pork loin segments, with an average weight of 0.57±0.12kg, were divided into four groups with three being inoculated by immersion with 7logCFU/ml of either Salmonella Typhimurium, Campylobacter coli or Listeria innocua and the last one inoculated by immersion with sterile medium (control group). The loin segments were treated with a seasoning mixture of curing agents and spices, packed in a synthetic sausage casing and cured for 64days. Microbiological analysis, pH and water activity (aw) were assessed at four stages. The values of pH and aw decreased with curing time as expected. S. Typhimurium and C. coli dropped significantly (3.28 and 2.14 log units, respectively), but limited reduction of L. innocua (0.84 log unit) was observed along the curing process. In our study, three factors were considered critical: the initial concentration of the bacteria, the progressive reduction of pH and the reduction of aw values. Our results encourage performing periodic analysis at different stages of the manufacturing of dry cured pork loins to ensure the absence of the three evaluated foodborne pathogens.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.016
      Issue No: Vol. 258 (2017)
  • Bacterial species and mycotoxin contamination associated with locust bean,
           melon and their fermented products in south-western Nigeria
    • Authors: Bamidele S. Adedeji; Obinna T. Ezeokoli; Chibundu N. Ezekiel; Adewale O. Obadina; Yinka M. Somorin; Michael Sulyok; Rasheed A. Adeleke; Benedikt Warth; Cyril C. Nwangburuka; Adebukola M. Omemu; Olusola B. Oyewole; Rudolf Krska
      Pages: 73 - 80
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Bamidele S. Adedeji, Obinna T. Ezeokoli, Chibundu N. Ezekiel, Adewale O. Obadina, Yinka M. Somorin, Michael Sulyok, Rasheed A. Adeleke, Benedikt Warth, Cyril C. Nwangburuka, Adebukola M. Omemu, Olusola B. Oyewole, Rudolf Krska
      The microbiological safety of spontaneously fermented foods is not always guaranteed due to the undefined fermenting microbial consortium and processing materials. In this study, two commonly consumed traditional condiments (iru and ogiri) and their respective raw seeds (locust bean and melon) purchased from markets in south-western Nigeria were assessed for bacterial diversity and mycotoxin contamination using 16S rRNA gene sequencing and liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. Two hundred isolates obtained from the raw seeds and condiments clustered into 10 operational taxonomic units (OTUs) and spanned 3 phyla, 10 genera, 14 species and 2 sub-species. Bacillus (25%) and Staphylococcus (23.5%) dominated other genera. Potentially pathogenic species such as Alcaligenes faecalis, Bacillus anthracis, Proteus mirabilis and Staphylococcus sciuri subsp. sciuri occurred in the samples, suggesting poor hygienic practice during production and/or handling of the condiments. A total of 48 microbial metabolites including 7 mycotoxins [3-nitropropionic acid, aflatoxin B1 (AFB1), AFB2, beauvericin, citrinin, ochratoxin A and sterigmatocystin] were quantified in the food samples. Melon and ogiri had detectable aflatoxin levels whereas locust bean and iru did not; the overall mycotoxin levels in the food samples were low. There is a need to educate processors/vendors of these condiments on good hygienic and processing practices.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.014
      Issue No: Vol. 258 (2017)
  • Aspergilli with Neosartorya-type ascospores: heat resistance and effect of
           sugar concentration on growth and spoilage incidence in berry products
    • Authors: Elettra Berni; Roberta Tranquillini; Nicoletta Scaramuzza; Andrea Brutti; Valentina Bernini
      Pages: 81 - 88
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Elettra Berni, Roberta Tranquillini, Nicoletta Scaramuzza, Andrea Brutti, Valentina Bernini
      This study focused on four different heat resistant aspergilli: two strains of Aspergillus hiratsukae (≡ Neosartorya hiratsukae), one strain of Aspergillus neoglaber (≡ Neosartorya glabra), and one strain of Aspergillus thermomutatus (≡ Neosartorya pseudofischeri), all isolated from spoiled pasteurized products. Their heat-resistance, the sugar concentration limiting their germination and growth in berry-based media, and a possible relation between the contamination levels of the raw materials used and the spoilage incidence in strawberry jams were assessed. Heat resistance data obtained from thermal death curves showed that the D values of the strains tested ranged between 3.7 and 13.5min at 87°C; 1.5 and 3.5min at 90°C; and 0.3 and 0.4min at 95°C in glucose solution. Similarly, D values ranged between 3.3 and 15.4min at 87°C; 1.3 and 4.3min at 90°C; and 0.3 and 0.6min at 95°C in strawberry-based formulation. For all strains, the corresponding z-values ranged between 5.7 and 8.3°C in glucose solution and from 5.7 to 8.4°C in strawberry formulation. With regard to the limitation of fungal germination and growth in fruit-based media, sucrose concentrations required to avoid growth varied between 45.0 and 55.0% for strawberry medium and between 42.5% and 50.0% for blueberry medium. Spore inactivation was observed below aw 0.88–0.91 for strawberries and aw 0.87–0.90 for blueberries; above 49.7–56.5°Bx for strawberries and 49.6–56.0°Bx for blueberries. The threshold optical refractometric residue proved strain-dependent, but substrate-independent, as for each strain the highest Brix degree value at which germination occurred was the same on both media, despite their different sucrose concentrations. With regard to the relation between contamination of raw materials by heat-resistant mould spores and spoilage incidence on final product, an equation was modelled to estimate the occurrence of fungal spoilage in strawberry jams for low contamination levels (26–46CFU/kg). Although it could not be used as a definitive tool to predict final spoilage in such of products, it could give important practical information to jam producers in preventing spoilage of their products.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.008
      Issue No: Vol. 258 (2017)
  • Fungal diversity of “Tomme d'Orchies” cheese during the ripening
           process as revealed by a metagenomic study
    • Authors: Alexandre Ceugniez; Bernard Taminiau; Françoise Coucheney; Philippe Jacques; Véronique Delcenserie; Georges Daube; Djamel Drider
      Pages: 89 - 93
      Abstract: Publication date: 3 October 2017
      Source:International Journal of Food Microbiology, Volume 258
      Author(s): Alexandre Ceugniez, Bernard Taminiau, Françoise Coucheney, Philippe Jacques, Véronique Delcenserie, Georges Daube, Djamel Drider
      Tomme d'Orchies is an artisanal pressed and uncooked cheese produced and marketed in the north of France. This study aimed at showing the fungal microbiota evolution of this cheese using a metagenetic based Illumina technology targeting the ITS2 domain of 5.8S fungal rDNAs. To this end, samples were taken from the rind and the core of different cheeses, after 0, 1, 3, 7, 14 and 21days of ripening. The data underpinned the prevalence of Yarrowia lipolytica and Galactomyces geotrichum for both microbiotas. Unusual species including Clavispora lusitaniae, Kazachstania unispora and Cladosporium cladosporioides were also detected, but their origins remain to be ascertained. The metagenomic revealed also the presence of Kluyveromyces and Debaryomyces species.

      PubDate: 2017-08-17T10:24:40Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.015
      Issue No: Vol. 258 (2017)
  • Prevalence and characterization of extended-spectrum β-lactamase (ESBL)
           and AmpC β-lactamase producing Enterobacteriaceae in fresh pork meat at
           processing level in Germany
    • Authors: Franziska Schill; Amir Abdulmawjood; Günter Klein; Felix Reich
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Franziska Schill, Amir Abdulmawjood, Günter Klein, Felix Reich
      ESBL or AmpC β-lactamase producing Enterobacteriaceae is an increasing concern in human medicine. A distribution via the food chain is discussed, but less is known about these bacteria on fresh pork meat. The aim of this study was to investigate the prevalence of ESBL/AmpC Enterobacteriaceae bacteria in fresh pork meat at processing level in Germany. The analysis comprised microbiological hygiene parameters and further pheno- and genotypical characterization of ESBL/AmpC isolates. The examination included three pools of meat and one corresponding meat juice sample from each of the tested pork meat batches (n=63). ESBL/AmpC producers were found in 42.9% (36.5% confirmed by genotype, gt) of the investigated batches, either in meat or meat juice. Meat juice was more often (28.6%) contaminated with ESBL/AmpC bacteria than meat (20.6%). Hygiene parameters were satisfactory in all samples and were thus not a suitable tool for predicting the presence of ESBL/AmpC producers. Most of the 37 confirmed ESBL/AmpC bacteria were identified as Escherichia coli (n=18) or Serratia fonticola (n=13). Susceptibility testing identified 32 of the 37 isolates to be multidrug-resistant. The most common resistance genes TEM, SHV, and CTX-M were found in 19 of the ESBL/AmpC isolates, mostly E. coli. A single detected AmpC β-lactamase producing E. coli carried a CMY-2 gene. Multilocus sequence typing (MLST) investigations of the ESBL/AmpC E. coli revealed 11 different sequence types. In conclusion, fresh pork meat can harbor highly diverse multidrug-resistant ESBL Enterobacteriaceae, even though at low rates. The study suggests that fresh pork meat might be a source for multidrug-resistant ESBL/AmpC Enterobacteriaceae of various origins. Therefore these data contribute to the epidemiological understanding of the distribution of resistant bacteria and the impact of the food chain on public health.

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.010
      Issue No: Vol. 257 (2017)
  • β-galactosidase from Aspergillus lacticoffeatus: A promising biocatalyst
           for the synthesis of novel prebiotics
    • Authors: Beatriz B. Cardoso; Sara C. Silvério; Luís Abrunhosa; José A. Teixeira; Lígia R. Rodrigues
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Beatriz B. Cardoso, Sara C. Silvério, Luís Abrunhosa, José A. Teixeira, Lígia R. Rodrigues
      β-galactosidase (EC are interesting enzymes able to catalyze lactose hydrolysis and transfer reactions to produce lactose-based prebiotics with potential application in the pharmaceutical and food industry. In this work, Aspergillus lacticoffeatus is described, for the first time, as an effective β-galactosidase producer. The extracellular enzyme production was evaluated in synthetic and alternative media containing cheese whey and corn steep liquor. Although β-galactosidase production occurred in all media (expect for the one composed solely by cheese whey), the highest enzymatic activity values (460U/mL) were obtained for the synthetic medium. Ochratoxin A production in synthetic medium was also evaluated and 9days of fermentation was identified as a suitable fermentation time to obtain a crude extract enzyme with mycotoxin concentration below the legal comparable value established for wine and grape juices (2ng/mL). The optimal pH and temperature for the crude extract enzyme was found in the range of 3.5–4.5 and 50–60°C, respectively. The β-galactosidase activity was reduced in the presence of Ba2+, Fe2+, Li+, K+ and galactose, while additives (except for ascorbic acid) and detergents exhibited a positive effect on enzymatic activity. This enzyme was able to catalyze the synthesis of prebiotics, namely lactulose (2.5g/L) and a galacto-oligosaccharide (trisaccharide, 6.3g/L), either when whole cells or crude enzyme was used as biocatalyst. The lactulose production using fungal whole cells is herein reported for the first time. Additionally, A. lacticoffeatus was also found to produce an enzyme with fructosyltransferase activity and other prebiotics, namely fructo-oligosaccharide 1-kestose (2.4g/L).

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.013
      Issue No: Vol. 257 (2017)
  • Detection of Mycobacterium avium subspecies paratuberculosis in powdered
           infant formula using IS900 quantitative PCR and liquid culture media
    • Authors: Kamal R. Acharya; Navneet K. Dhand; Richard J. Whittington; Karren M. Plain
      Pages: 1 - 9
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Kamal R. Acharya, Navneet K. Dhand, Richard J. Whittington, Karren M. Plain
      Mycobacterium avium subspecies paratuberculosis (MAP) has been implicated in Crohn's disease in humans resulting in public concern over the presence of MAP in powdered infant formula, which could contribute towards early human exposure to MAP or MAP components. Testing of representative powdered infant formula samples using effective tests is required to provide information on contamination of infant formula with MAP, so that consumers can make informed decisions. This study aimed to test representative powdered infant formula samples for the presence of MAP using a quantitative PCR and liquid culture method. For this purpose, an efficient DNA extraction method was developed and an optimum decontamination protocol for culture method was identified. A total of 122 powdered infant formula samples were tested, comprising 72 brands produced by 12 manufacturers from 9 countries. Powdered infant formula samples were reconstituted and centrifuged to separate the casein pellet, cream layer and whey fraction. A sensitive qPCR test was performed on DNA extracted from the casein pellet. In addition, the cream layer and casein pellet were cultured in liquid media, following decontamination with the optimum protocol. Of the 122 samples tested, 6 were positive for MAP DNA but none were positive for growth in culture at 12 and 20 weeks. The limit of detection of the quantitative PCR was less than 5 MAP organisms per 1.5g milk powder. The methods developed in the study could be used for quality assurance testing for infant formula and calf milk replacers. The low contamination level of MAP and absence of viable forms in our study suggests a relatively low risk of exposure of infants to MAP components.

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.005
      Issue No: Vol. 257 (2017)
  • Influence of lactic acid and post-treatment recovery time on the heat
           resistance of Listeria monocytogenes
    • Authors: Yasuo Omori; Kiyotaka Miake; Hiromi Nakamura; Eriko Kage-Nakadai; Yoshikazu Nishikawa
      Pages: 10 - 18
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Yasuo Omori, Kiyotaka Miake, Hiromi Nakamura, Eriko Kage-Nakadai, Yoshikazu Nishikawa
      The aim of this study was to evaluate the effect of lactic acid (LA) with and without organic material at various post-treatment recovery times on the heat resistance of Listeria monocytogenes (Lm). LA decreased Lm numbers; however, the effect was remarkably attenuated by the presence of organic matter. Five strains of Lm were treated with LA and the listericidal effects were compared. The effect of LA varied depending on the strain, with ≥3.0% (w/w) LA required to kill the Lm strains in a short time. The heat resistance of Lm treated with LA was examined with respect to the time interval between the acid treatment and the subsequent manufacturing step. The heat resistance of Lm was shown to significantly increase during the post-treatment period. Heat tolerance (D value) increased up to 3.4-fold compared with the non-treated control bacteria. RNA sequencing and RT-PCR analyses suggested that several stress chaperones, proteins controlled by RecA and associated with high-temperature survival, were involved in the mechanism of enhanced heat resistance. These results are applicable to manufacturers when LA and heat treatment methods are utilized for the effective control of Lm in foods.

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.008
      Issue No: Vol. 257 (2017)
  • Disinfection efficiencies of sage and spearmint essential oils against
           planktonic and biofilm Staphylococcus aureus cells in comparison with
           sodium hypochlorite
    • Authors: Dimitrios Vetas; Eleni Dimitropoulou; Gregoria Mitropoulou; Yiannis Kourkoutas; Efstathios Giaouris
      Pages: 19 - 25
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Dimitrios Vetas, Eleni Dimitropoulou, Gregoria Mitropoulou, Yiannis Kourkoutas, Efstathios Giaouris
      Staphylococcus aureus causes human infections and foodborne intoxications. This study explored the potential antibacterial actions of sage and spearmint essential oils (EOs) against both its planktonic and biofilm cells, in comparison with sodium hypochlorite (NaOCl), a commonly applied chemical sanitizer. Initially, the minimum inhibitory and bactericidal concentrations (MICs, MBCs) of each plant mixture were determined against planktonic cultures, following growth at 30°C for 24h. Stationary phase planktonic bacteria were then individually exposed for 6min to either each EO (applied at 1–2×MBC; 2.5–5%), or NaOCl (250–450ppm). These were also left to form biofilms on 96-well polystyrene microplates, at 30°C for 96h, with medium renewal at 48h, in the presence of 10 different concentrations of each EO, expanding from sub- to super-inhibitory for planktonic growth, and the minimum biofilm inhibitory concentrations (MBICs; >90% inhibition) of each plant mixture were calculated. Formed biofilms were finally exposed for 6min to either each EO (applied at 2–6×MBC; 5–15%), or NaOCl (7500–25,000ppm; applied either alone or in combination with each EO at 5%). Results showed that both EOs presented MIC and MBC equal to 1.25 and 2.5%, respectively. As expected, their application at their MIC and above significantly inhibited biofilm formation, while spearmint EO was still able to cause this at ½ of its MIC, with MBICs equal to 1.25 and 0.63% for sage and spearmint EOs, respectively. Alarmingly, the application of both EOs at 1/8 to 1/16 of their MIC further increased biofilm formation. Regarding biofilm disinfection experiments, the individual application of each EO against the pre-established sessile communities resulted in log decrease ranges of 0.8–3logCFU/cm2, while in the case of NaOCl application (either alone or combined with each EO), the observed reductions never exceeded 1.7logCFU/cm2. These last results highlight the great antimicrobial recalcitrance of biofilm communities, found here to be ca. 100 times more resistant to NaOCl compared to planktonic ones, and stress the urgent need for further research on alternative, adequate and safe disinfection strategies to control them in food processing and other environments.

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.003
      Issue No: Vol. 257 (2017)
  • Impact of Saccharomyces cerevisiae and Torulaspora delbrueckii starter
           cultures on cocoa beans fermentation
    • Authors: Simonetta Visintin; Lacerda Ramos; Nara Batista; Paola Dolci; Freitas Schwan; Luca Cocolin
      Pages: 31 - 40
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Simonetta Visintin, Lacerda Ramos, Nara Batista, Paola Dolci, Freitas Schwan, Luca Cocolin
      Aim of this work was to study the impact of mixed cultures of Saccharomyces cerevisiae and Torulaspora delbrueckii and T. delbrueckii monoculture on the fermentation process conducted on two different cocoa hybrids, PS1319 and SJ02, in Bahia, Brazil. This was performed throughout studying physico-chemical changes during the fermentation process and analyzing volatile compounds and sensory analysis of chocolates. (GTG)5-PCR fingerprinting was used to type isolates at strain level allowing to assess the implantation of the starter cultures added. Resulted clusters were composed by T. delbrueckii strains isolated during the first 24h of fermentation. On the contrary, S. cerevisiae, the most strongly fermenting ethanol-tolerant species, took over the fermentation at a second stage. Quantification data of T. delbrueckii during spontaneous fermentation confirm the attitude of this species of not being so commonly involved in this process. This study also showed that the inoculum influenced the PS1319 hybrid end-product quality, changing analytic profile and sensory perception of chocolates. No big influences were recorded for SJ02 hybrid, but this may be improved. In combination with S. cerevisiae, T. delbrueckii had a positive influence on the analytical profile of chocolates. The application of starter cultures did change the aroma profile of the resulting chocolate as determined by GC–MS; in some case the differences observed had a significantly impact on the consumer perception of the chocolates.

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.004
      Issue No: Vol. 257 (2017)
  • Transcriptome analysis shows activation of the arginine deiminase pathway
           in Lactococcus lactis as a response to ethanol stress
    • Authors: Lorena Díez; Ana Solopova; Rocío Fernández-Pérez; Miriam González; Carmen Tenorio; Oscar P. Kuipers; Fernanda Ruiz-Larrea
      Pages: 41 - 48
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Lorena Díez, Ana Solopova, Rocío Fernández-Pérez, Miriam González, Carmen Tenorio, Oscar P. Kuipers, Fernanda Ruiz-Larrea
      This paper describes the molecular response of Lactococcus lactis NZ9700 to ethanol. This strain is a well-known nisin producer and a lactic acid bacteria (LAB) model strain. Global transcriptome profiling using DNA microarrays demonstrated a bacterial adaptive response to the presence of 2% ethanol in the culture broth and differential expression of 67 genes. The highest up-regulation was detected for those genes involved in arginine degradation through the arginine deiminase (ADI) pathway (20–40 fold up-regulation). The metabolic responses to ethanol of wild type L. lactis strains were studied and compared to those of regulator-deletion mutants MG∆argR and MG∆ahrC. The results showed that in the presence of 2% ethanol those strains with an active ADI pathway reached higher growth rates when arginine was available in the culture broth than in absence of arginine. In a chemically defined medium strains with an active ADI pathway consumed arginine and produced ornithine in the presence of 2% ethanol, hence corroborating that arginine catabolism is involved in the bacterial response to ethanol. This is the first study of the L. lactis response to ethanol stress to demonstrate the relevance of arginine catabolism for bacterial adaptation and survival in an ethanol containing medium.

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.017
      Issue No: Vol. 257 (2017)
  • Validation of a commercial kit aimed to the detection of pathogenic
           anisakid nematodes in fish products
    • Authors: Serena Cavallero; Alessandro Bruno; Enrico Arletti; Monica Caffara; Maria Letizia Fioravanti; Antonella Costa; Gaetano Cammilleri; Stefania Graci; Vincenzo Ferrantelli; Stefano D'Amelio
      Pages: 75 - 79
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Serena Cavallero, Alessandro Bruno, Enrico Arletti, Monica Caffara, Maria Letizia Fioravanti, Antonella Costa, Gaetano Cammilleri, Stefania Graci, Vincenzo Ferrantelli, Stefano D'Amelio
      Anisakids are parasitic nematodes responsible for a zoonosis that occurs following the ingestion of fish and fish products infected with larvae belonging to the genera Anisakis and Pseudoterranova. Rarely Contracaecum is found in association with gastric/intestinal illness, while Hysterothylacium is commonly considered not pathogenic. Although Real Time PCR assays have been recently used with the aim to detect and quantify these parasites in food products, methods applied did not undergo through extensive validation process, a feature highly desirable or mandatory in the case of testing laboratories accredited for the ISO EN 17025:2005. Here, a comprehensive study has been performed to validate a commercial kit based on multiplex real time PCR for the qualitative detection of Anisakis and Pseudoterranova. Inclusivity/exclusivity trials were carried out on DNA from species of the genera Anisakis, Pseudoterranova, Contracaecum, Hysterothylacium and Ascaris, on fish intentionally contaminated with Anisakis spp. and Pseudoterranova spp. and on marine organisms as fish, crustacean and squid to test the commercial kit on a large sample. The assay gave positive amplification for several Anisakis and Pseudoterranova species, while providing no signal for the members of the remaining genera. Each sample was correctly assigned either to Anisakis or Pseudoterranova, thus indicating that no cross-reaction occurred. The LOD was determined using two independent standard curves. Robustness was assayed by using two different thermocyclers in three distinct laboratories with different operators. The establishment of a validation dossier will permit the use of the commercial kit for the detection of Anisakis and Pseudoterranova DNA in fish and fish products intended for human consumption by public or private laboratories, following the requirements regarding the quality assurance processes described in the ISO EN 17025:2005.

      PubDate: 2017-06-22T09:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.011
      Issue No: Vol. 257 (2017)
  • A metagenomic assessment of viral contamination on fresh parsley plants
           irrigated with fecally tainted river water
    • Authors: X. Fernandez-Cassi; N. Timoneda; E. Gonzales-Gustavson; J.F. Abril; S. Bofill-Mas; R. Girones
      Pages: 80 - 90
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): X. Fernandez-Cassi, N. Timoneda, E. Gonzales-Gustavson, J.F. Abril, S. Bofill-Mas, R. Girones
      Microbial food-borne diseases are still frequently reported despite the implementation of microbial quality legislation to improve food safety. Among all the microbial agents, viruses are the most important causative agents of food-borne outbreaks. The development and application of a new generation of sequencing techniques to test for viral contaminants in fresh produce is an unexplored field that allows for the study of the viral populations that might be transmitted by the fecal-oral route through the consumption of contaminated food. To advance this promising field, parsley was planted and grown under controlled conditions and irrigated using contaminated river water. Viruses polluting the irrigation water and the parsley leaves were studied by using metagenomics. To address possible contamination due to sample manipulation, library preparation, and other sources, parsley plants irrigated with nutritive solution were used as a negative control. In parallel, viruses present in the river water used for plant irrigation were analyzed using the same methodology. It was possible to assign viral taxons from 2.4 to 74.88% of the total reads sequenced depending on the sample. Most of the viral reads detected in the river water were related to the plant viral families Tymoviridae (66.13%) and Virgaviridae (14.45%) and the phage viral families Myoviridae (5.70%), Siphoviridae (5.06%), and Microviridae (2.89%). Less than 1% of the viral reads were related to viral families that infect humans, including members of the Adenoviridae, Reoviridae, Picornaviridae and Astroviridae families. On the surface of the parsley plants, most of the viral reads that were detected were assigned to the Dicistroviridae family (41.52%). Sequences related to important viral pathogens, such as the hepatitis E virus, several picornaviruses from species A and B as well as human sapoviruses and GIV noroviruses were detected. The high diversity of viral sequences found in the parsley plants suggests that irrigation on fecally-tainted food may have a role in the transmission of a wide diversity of viral families. This finding reinforces the idea that the best way to avoid food-borne viral diseases is to introduce good field irrigation and production practices. New strains have been identified that are related to the Picornaviridae and distantly related to the Hepeviridae family. However, the detection of a viral genome alone does not necessarily indicate there is a risk of infection or disease development. Thus, further investigation is crucial for correlating the detection of viral metagenomes in samples with the risk of infection. There is also an urgent need to develop new methods to improve the sensitivity of current Next Generation Sequencing (NGS) techniques in the food safety area.

      PubDate: 2017-08-17T10:24:40Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.001
      Issue No: Vol. 257 (2017)
  • Effect of different packaging materials containing
           poly-[2-(tert-butylamino) methylstyrene] on the growth of spoilage and
           pathogenic bacteria on fresh meat
    • Authors: S. Dohlen; C. Braun; F. Brodkorb; B. Fischer; Y. Ilg; K. Kalbfleisch; R. Lorenz; M. Kreyenschmidt; J. Kreyenschmidt
      Pages: 91 - 100
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): S. Dohlen, C. Braun, F. Brodkorb, B. Fischer, Y. Ilg, K. Kalbfleisch, R. Lorenz, M. Kreyenschmidt, J. Kreyenschmidt
      The objective of this study was to investigate the effect of novel antimicrobial packaging materials containing poly-[2-(tertbutylamino) methylstyrene] (poly(TBAMS)) on the growth of typical spoilage and pathogenic bacteria present on meat. The antimicrobial activity of materials containing different poly(TBAMS) concentrations was determined by comparing the bacterial counts on reference and sample materials at different temperatures and times and in the presence of meat components. Storage tests with poultry fillets and veal cutlets were conducted with samples vacuum packaged in the reference foil and foil containing 10% poly(TBAMS). After specific time intervals, typical spoilage microorganisms, total viable count (TVC), sensory changes and pH value were analysed. The results of the different poly(TBAMS) containing packaging materials showed an increase of the antimicrobial activity with an increasing amount of poly(TBAMS) in the base polymer. A high antimicrobial activity against inoculum of spoilage and pathogenic organisms typical for meat products was detected of a multilayer foil containing 10% poly(TBAMS) in the inner layer after 24h at 7°C. Gram positive-bacteria were more sensitive to poly(TBAMS) foil than gram-negative bacteria. In storage tests however, over the entire storage, a significant effect of this poly(TBAMS) foil on microbial growth on chicken breast fillets and veal cutlets could not be identified. Poly(TBAMS) packaging materials showed very good antimicrobial properties against a wide range of bacteria. However, for a significant inhibition of microbial growth on fresh meat, a higher amount of poly(TBAMS) was necessary to prolong the shelf life of meat.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.007
      Issue No: Vol. 257 (2017)
  • Application of water-assisted ultraviolet light in combination of chlorine
           and hydrogen peroxide to inactivate Salmonella on fresh produce
    • Authors: Shuanghuan Guo; Runze Huang; Haiqiang Chen
      Pages: 101 - 109
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Shuanghuan Guo, Runze Huang, Haiqiang Chen
      With the demand for fresh produce increases in recent decades, concerns for microbiological safety of fresh produce are also raised. To identify effective ultraviolet (UV) light treatment for fresh produce decontamination, we first determined the effect of three forms of UV treatment, dry UV (samples were treated by UV directly), wet UV (samples were dipped in water briefly and then exposed to UV), and water-assisted UV (samples were treated by UV while being immersed in agitated water) on inactivation of Salmonella inoculated on tomatoes and fresh-cut lettuce. In general, the water-assisted UV treatment was found to be the most effective for both produce items. Chlorine and hydrogen peroxide were then tested to determine whether they could be used to enhance the decontamination efficacy of water-assisted UV treatment and prevent transfer of Salmonella via wash water by completely eliminating it. Neither of them significantly enhanced water-assisted UV inactivation of Salmonella on tomatoes. Chlorine significantly improved the decontamination effectiveness of the water-assisted UV treatment for baby-cut carrots and lettuce, but not for spinach. In general, the single water-assisted UV treatment and the combined treatment of water-assisted UV and chlorine were similar or more effective than the chlorine washing treatment. In most of the cases, no Salmonella was detected in the wash water when the single water-assisted UV treatment was used to decontaminate tomatoes. In a few cases when Salmonella was detected in the wash water, the populations were very low,≤2CFU/mL, and the wash water contained an extremely high level of organic load and soil level. Therefore, the single water-assisted UV treatment could potentially be used as an environmentally friendly and non-chemical alternative to chlorine washing for tomatoes after validation in industrial scale. For lettuce, spinach and baby-cut carrots, the combined treatment of water-assisted UV treatment and chlorine was needed to maintain a pathogen free environment in the wash water so that cross contamination could be prevented during fresh produce washing.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.017
      Issue No: Vol. 257 (2017)
  • Rhizopus oryzae – Ancient microbial resource with importance in
           modern food industry
    • Authors: Liliana Londoño-Hernández; Cristina Ramírez-Toro; Héctor A. Ruiz; Juan A. Ascacio-Valdés; Miguel A. Aguilar-Gonzalez; Raúl Rodríguez-Herrera; Cristóbal N. Aguilar
      Pages: 110 - 127
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Liliana Londoño-Hernández, Cristina Ramírez-Toro, Héctor A. Ruiz, Juan A. Ascacio-Valdés, Miguel A. Aguilar-Gonzalez, Raúl Rodríguez-Herrera, Cristóbal N. Aguilar
      Filamentous fungi are microorganisms widely known for their diverse biochemical features. Fungi can efficiently invade a wide variety of substrates under operational conditions producing numerous bioproducts of interest, such as enzymes, organic acids, aromatic compounds and colorants. An additional interesting characteristic of some fungi is their safety classification for different uses, which guarantees that the bioproducts obtained from them do not contain any toxic component deleterious to humans. Rhizopus oryzae is among this group of fungi and is classified as a GRAS filamentous fungus, commonly used for production of some oriental traditional foods. It is mainly recognized as a good producer of lactic acid; however, its potential for other biotechnological processes is under study. This review analyzes and discusses the current scientific and technical contributions which may maximize the potential of R. oryzae as a producer of different compounds of industrial interest.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.012
      Issue No: Vol. 257 (2017)
  • Leuconostoc mesenteroides and Leuconostoc pseudomesenteroides
           bacteriophages: Genomics and cross-species host ranges
    • Authors: Silvina A. Pujato; Daniela M. Guglielmotti; Manuel Martínez-García; Andrea Quiberoni; Francisco J.M. Mojica
      Pages: 128 - 137
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Silvina A. Pujato, Daniela M. Guglielmotti, Manuel Martínez-García, Andrea Quiberoni, Francisco J.M. Mojica
      Unveiling virus-host interactions are relevant for understanding the biology and evolution of microbes globally, but in particular, it has also a paramount impact on the manufacture of fermented dairy products. In this study, we aim at characterizing phages infecting the commonly used heterofermentative Leuconostoc spp. on the basis of host range patterns and genome analysis. Host range of six Leuconostoc phages was investigated using three methods (efficiency of plaquing, spot and turbidity tests) against Ln. mesenteroides and Ln. pseudomesenteroides strains. Complete genome sequencing from four out of the six studied Leuconostoc phages were obtained in this work, while the remaining two have been sequenced previously. According to our results, cross-species host specificity was demonstrated, as all phages tested were capable of infecting both Ln. pseudomesenteroides and Ln. mesenteroides strains, although with different efficiency of plaquing (EOP). Phage adsorption rates and ability of low-EOP host strains to propagate phages by crossing the Leuconostoc species' barrier confirm results. At the genome level, phages CHA, CHB, Ln-7, Ln-8 and Ln-9 revealed high similarity with previously characterized phages infecting mostly Ln. mesenteroides strains, while phage LDG was highly similar to phages infecting Ln. pseudomesenteroides. Additionally, correlation between receptor binding protein (RBP) and host range patterns allowed us to unveil a finer clustering of Leuconostoc phages studied into four groups. This is the first report of overlapped phage host ranges between Leuconostoc species.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.009
      Issue No: Vol. 257 (2017)
  • A survey of oenophages during wine making reveals a novel group with
           unusual genomic characteristics
    • Authors: Cécile Philippe; Fety Jaomanjaka; Olivier Claisse; Rémi Laforgue; Julie Maupeu; Melina Petrel; Claire Le Marrec
      Pages: 138 - 147
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Cécile Philippe, Fety Jaomanjaka, Olivier Claisse, Rémi Laforgue, Julie Maupeu, Melina Petrel, Claire Le Marrec
      Oenophages have so far been mostly isolated from red wines under malolactic fermentation (MLF), and correspond to temperate or ex-temperate phages of Oenococcus oeni. Their genomes are clustered into 4 integrase gene sequence groups, which are also related to the chromosomal integration site. Our aims were to survey the occurrence of oenophages in a broader and more diverse collection of samples than those previously explored. Active phages were isolated from 33 out of 166 samples, which mostly originated from must and MLF. Seventy one phage lysates were produced and 30% were assigned to a novel group with unusual genomic characteristics, called unk. All unk members produced similar RAPD and DNA restriction patterns, were negative by PCR for the signature sequences previously identified in the integrase and endolysin genes of oenophages, and lacked any BamHI restriction site in their genome. The data support that development of additional and novel signature genes for assessing oenophage diversity is now required.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.014
      Issue No: Vol. 257 (2017)
  • Microbial community profiling of fresh basil and pitfalls in taxonomic
           assignment of enterobacterial pathogenic species based upon 16S rRNA
           amplicon sequencing
    • Authors: Siele Ceuppens; Dieter De Coninck; Nadine Bottledoorn; Filip Van Nieuwerburgh; Mieke Uyttendaele
      Pages: 148 - 156
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Siele Ceuppens, Dieter De Coninck, Nadine Bottledoorn, Filip Van Nieuwerburgh, Mieke Uyttendaele
      Application of 16S rRNA (gene) amplicon sequencing on food samples is increasingly applied for assessing microbial diversity but may as unintended advantage also enable simultaneous detection of any human pathogens without a priori definition. In the present study high-throughput next-generation sequencing (NGS) of the V1–V2–V3 regions of the 16S rRNA gene was applied to identify the bacteria present on fresh basil leaves. However, results were strongly impacted by variations in the bioinformatics analysis pipelines (MEGAN, SILVAngs, QIIME and MG-RAST), including the database choice (Greengenes, RDP and M5RNA) and the annotation algorithm (best hit, representative hit and lowest common ancestor). The use of pipelines with default parameters will lead to discrepancies. The estimate of microbial diversity of fresh basil using 16S rRNA (gene) amplicon sequencing is thus indicative but subject to biases. Salmonella enterica was detected at low frequencies, between 0.1% and 0.4% of bacterial sequences, corresponding with 37 to 166 reads. However, this result was dependent upon the pipeline used: Salmonella was detected by MEGAN, SILVAngs and MG-RAST, but not by QIIME. Confirmation of Salmonella sequences by real-time PCR was unsuccessful. It was shown that taxonomic resolution obtained from the short (500bp) sequence reads of the 16S rRNA gene containing the hypervariable regions V1–V3 cannot allow distinction of Salmonella with closely related enterobacterial species. In conclusion 16S amplicon sequencing, getting the status of standard method in microbial ecology studies of foods, needs expertise on both bioinformatics and microbiology for analysis of results. It is a powerful tool to estimate bacterial diversity but amenable to biases. Limitations concerning taxonomic resolution for some bacterial species or its inability to detect sub-dominant (pathogenic) species should be acknowledged in order to avoid overinterpretation of results.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.016
      Issue No: Vol. 257 (2017)
  • Tracking of Listeria monocytogenes in meat establishment using Whole
           Genome Sequencing as a food safety management tool: A proof of concept
    • Authors: Ivan Nastasijevic; Dubravka Milanov; Branko Velebit; Vesna Djordjevic; Craig Swift; Anais Painset; Brankica Lakicevic
      Pages: 157 - 164
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Ivan Nastasijevic, Dubravka Milanov, Branko Velebit, Vesna Djordjevic, Craig Swift, Anais Painset, Brankica Lakicevic
      Repeated Listeria outbreaks particularly associated with Ready-To-Eat (RTE) delicatessen meat products have been reported annually at global level. The most frequent scenario that led to foodborne outbreaks was the post-thermal treatment cross-contamination of deli meat products during slicing and modified atmosphere packaging (MAP). The precondition for such cross contamination is the previous introduction of Listeria into meat processing facilities and subsequent colonization of the production environment, associated with formation of biofilms resilient to common sanitation procedures regularly applied in meat establishments. The use of Whole Genome Sequencing (WGS) can facilitate the understanding of contamination and colonization routes of pathogens within the food production environment and enable efficient pathogen tracking among different departments. This study aimed to: a) provide a proof of concept on practical use of WGS in a meat establishment to define the entry routes and spread pattern of L. monocytogenes, and b) to consider the regular use of WGS in meat processing establishments as a strong support of food safety management system. The results revealed that Listeria spp. was present in slaughter line, chilling chambers, deboning, slicing, MAP, as well as in corridors and dispatch (53 positive samples, out of 240). Eight L. monocytogenes isolates (out of 53) were identified from the slaughterhouse, chilling chambers, deboning, MAP and dispatch. L. monocytogenes isolates were of three different serotypes (1/2a, 1/2c, 4b) and correspondingly of three MLST sequence types. Overall, two pairs of L. monocytogenes isolates were genetically identical, i.e. two serotype 4b isolates (ST1), isolated from water drain at dispatch unit and two isolates obtained from slaughterhouse (floorwall junction at the carcass wash point) and MAP (water drain). These findings indicated that L. monocytogenes isolates identified in meat processing units (MAP, chilling chamber and dispatch) originated from the slaughter line. Further, all eight L. monocytogenes isolates were confirmed to be biofilm producers on glass and stainless steel surfaces. The identification of the main entry routes of L. monocytogenes into meat establishments and tracking the routes for spread of the pathogen are of essential importance to define appropriate risk mitigation strategies for L. monocytogenes in meat production environment. The routine use of WGS for bacterial characterization, as a strong support of food safety management system in meat establishments, will require the cost-effective approach. It may encompass in-house sequencing when sequencing equipment is used for multiple applications (e.g. WGS of pathogens, starter cultures and spoilage organisms).

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.015
      Issue No: Vol. 257 (2017)
  • Internalization of Listeria monocytogenes in cantaloupes during dump tank
           washing and hydrocooling
    • Authors: Dumitru Macarisin; Anna Wooten; Antonio De Jesus; Minji Hur; Seonjae Bae; Jitendra Patel; Peter Evans; Eric Brown; Thomas Hammack; Yi Chen
      Pages: 165 - 175
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Dumitru Macarisin, Anna Wooten, Antonio De Jesus, Minji Hur, Seonjae Bae, Jitendra Patel, Peter Evans, Eric Brown, Thomas Hammack, Yi Chen
      Recent listeriosis outbreaks and recalls associated with cantaloupes urge for studies to understand the mechanisms of cantaloupe contamination by Listeria monocytogenes. Postharvest practices such as washing and hydrocooling were suggested to facilitate the contamination of fresh fruits by human pathogens. This study assessed the potential of L. monocytogenes internalization into cantaloupes during dump tank washing and immersion-type hydrocooling in water contaminated with L. monocytogenes. The effect of cantaloupe cultivar, water temperature, and harvesting technique on L. monocytogenes internalization was also evaluated. Full slip (cantaloupe without any residual stem) Western and Eastern cultivar cantaloupes were pre-warmed to 42°C (to imitate peak-high field temperatures of freshly harvested cantaloupes) and then immersed in water at 6°C and 18°C containing 4 and 6logCFU/ml of L. monocytogenes. Clipped (cantaloupe with short stem residues obtained by clipping the stem at harvest) Western and Eastern cantaloupes were pre-warmed to 42°C and then immersed in water at 6°C containing 6logCFU/ml of L. monocytogenes. Additionally, full slip and clipped Western cantaloupes were equilibrated to 18°C and then immersed in water at 18°C containing 6logCFU/ml of L. monocytogenes (isothermal immersion without temperature differential). Water containing L. monocytogenes infiltrated both full slip and clipped cantaloupes through the stems/stem scars and was then distributed along the vascular system in hypodermal mesocarp reaching the calyx area of the fruit. The current study demonstrated that, under experimental conditions, L. monocytogenes can internalize into cantaloupes during immersion in water contaminated by L. monocytogenes, both in the presence and absence of temperature differential, and that temperature differential moderately enhanced the internalization of L. monocytogenes. The incidence and levels of L. monocytogenes internalized in the middle-mesocarp were significantly affected by harvesting technique but not by cantaloupe cultivar.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.018
      Issue No: Vol. 257 (2017)
  • Inactivation of viruses and bacteria on strawberries using a levulinic
           acid plus sodium dodecyl sulfate based sanitizer, taking sensorial and
           chemical food safety aspects into account
    • Authors: Zijin Zhou; Sophie Zuber; Frédérique Cantergiani; Sophie Butot; Dan Li; Thomas Stroheker; Frank Devlieghere; Anthony Lima; Umberto Piantini; Mieke Uyttendaele
      Pages: 176 - 182
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Zijin Zhou, Sophie Zuber, Frédérique Cantergiani, Sophie Butot, Dan Li, Thomas Stroheker, Frank Devlieghere, Anthony Lima, Umberto Piantini, Mieke Uyttendaele
      The efficacy of levulinic acid (LVA) in combination with sodium dodecyl sulfate (SDS) in removal of foodborne viruses, enteric bacterial pathogens and their surrogates on fresh strawberries was investigated. Inoculated strawberries were treated with potable water, sodium hypochlorite solution (50ppm), 0.5% LVA plus 0.5% SDS solution, and 5% LVA plus 2% SDS solution respectively for 2min, followed by spray-rinsing with potable water. Water washing removed at least 1.0-log of the tested viral and bacterial strains from the strawberries' surfaces. The 50ppm chlorine wash induced 3.4, 1.5 and 2.1-log reductions for hepatitis A virus (HAV), murine norovirus-1 (MNV-1) and MS2 bacteriophage, respectively. In comparison, the tested bacterial strains showed uniform reductions around 1.6-log CFU/ml. The 0.5% LVA plus 0.5% SDS wash induced 2.7, 1.4 and 2.4-log reductions for HAV, MNV-1 and MS2, which were comparable with the reductions induced by chlorine (P >0.05). For bacteria, over 2.0-log reductions were obtained for Enterococcus faecium, Listeria monocytogenes and Salmonella, while Escherichia coli O157:H7 and Escherichia coli P1 showed reductions of 1.9 and 1.8-log CFU/ml. Higher concentration of LVA plus SDS showed no significantly higher reductions (P >0.05). Sensory tests of washed strawberries and chemical residue analysis of LVA on strawberries after washing were also performed. In conclusion, this study demonstrates good performance of 0.5% LVA plus 0.5% SDS to reduce the levels of enteric pathogens if present on strawberries without altering taste and introducing chemical safety issues.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.023
      Issue No: Vol. 257 (2017)
  • Influence of Torulaspora delbrueckii in varietal thiol (3-SH and 4-MSP)
           release in wine sequential fermentations
    • Authors: Ignacio Belda; Javier Ruiz; Beata Beisert; Eva Navascués; Domingo Marquina; Fernando Calderón; Doris Rauhut; Santiago Benito; Antonio Santos
      Pages: 183 - 191
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Ignacio Belda, Javier Ruiz, Beata Beisert, Eva Navascués, Domingo Marquina, Fernando Calderón, Doris Rauhut, Santiago Benito, Antonio Santos
      In last years, non-Saccharomyces yeasts have emerged as innovative tools to improve wine quality, being able to modify the concentration of sensory-impact compounds. Among them, varietal thiols released by yeasts, play a key role in the distinctive aroma of certain white wines. In this context, Torulaspora delbrueckii is in the spotlight because of its positive contribution to several wine quality parameters. This work studies the physiological properties of an industrial T. delbrueckii strain, for the production of wines with increased thiol concentrations. IRC7 gene, previously described in S. cerevisiae, has been identified in T. delbrueckii, establishing the genetics basis of its thiol-releasing capability. Fermentations involving T. delbrueckii showed improvements on several parameters (such as glycerol content, ethanol index, and major volatile compounds composition), but especially on thiols release. These results confirm the potential of T. delbrueckii on wine improvement, describing new metabolic features regarding the release of cysteinylated aroma precursors.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.028
      Issue No: Vol. 257 (2017)
  • Characterization of antibiotic resistant and pathogenic Escherichia coli
           in irrigation water and vegetables in household farms
    • Authors: Susana Araújo; Isabel A.T. Silva; Marta Tacão; Carla Patinha; Artur Alves; Isabel Henriques
      Pages: 192 - 200
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Susana Araújo, Isabel A.T. Silva, Marta Tacão, Carla Patinha, Artur Alves, Isabel Henriques
      This study aimed to characterize Escherichia coli present in irrigation water and vegetables from 16 household farms. Isolates were obtained from 50% of water (n=210 isolates) and 38% of vegetable samples (n=239). Phylogroups B1 (56% of isolates) and A (22%) were the most prevalent both in water and vegetables. Diarrheagenic strains were detected in vegetables. Irrespective of the source (i.e. water or vegetables), the most common antibiotic resistance was against streptomycin (89% resistant isolates) and tetracycline (24%). Common acquired genes (e.g. bla TEM, tetA, tetB) were found in isolates from both sources. Class I integrons were detected in water (arrays dfrA1-aadA1 and dfr16-blaP1b-aadA2-ereA) and vegetables (unknown arrays). intI2 was detected in water (dfrA1-sat2-aadA1). Plasmids were detected in 14 isolates (IncFIC, IncFIB, IncFrep, IncI1 in both samples; IncY in vegetables). Plasmids from seven isolates were transferrable by conjugation, conferring resistance to antibiotics to the recipient strain. Multidrug-resistant (MDR) strains were isolated from water (12% of the unique isolates) and vegetables (21%). Predominant sequence types (STs) among MDR isolates were ST10, ST297 and ST2522. In some cases, the same STs and identical clones (as showed by rep-PCR typing) were detected in water and vegetables, suggesting cross-contamination. This study identified several risk factors in E. coli isolates from vegetables and irrigation water, raising health concerns. Also, results suggest that irrigation groundwater constitutes a source of E. coli that may enter the food chain through vegetables ingestion.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.020
      Issue No: Vol. 257 (2017)
  • Characterization of small-spored Alternaria from Argentinean crops through
           a polyphasic approach
    • Authors: Lucía da Cruz Cabral; Marcela Rodriguero; Sebastián Stenglein; Kristian Fog Nielsen; Andrea Patriarca
      Pages: 206 - 215
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Lucía da Cruz Cabral, Marcela Rodriguero, Sebastián Stenglein, Kristian Fog Nielsen, Andrea Patriarca
      Small-spored Alternaria have been isolated from a wide variety of food crops, causing both economic losses and human health risk due to the metabolites produced. Their taxonomy has been discussed widely, but no scientific consensus has been established in this field to date. Argentina is a major exporter of agricultural products, so it is essential to thoroughly understand the physiological behaviour of this pathogen in a food safety context. Thus, the objective of this work was to characterize small-spored Alternaria spp. obtained from tomato fruits, pepper fruits, wheat grains and blueberries from Argentina by a polyphasic approach involving metabolomic and phylogenetic analyses based on molecular and morphological characters. Morphological analysis divided the population studied into three groups; A. arborescens sp.-grp., A. tenuissima sp.-grp., and A. alternata sp.-grp. However, when these characters were simultaneously analysed with molecular data, no clearly separated groups were obtained. Haplotype network and phylogenetic analysis (both Bayesian and maximum parsimony) of a conserved region yielded the same result, suggesting that all isolates belong to the same species. Furthermore, no correlation could be established between morphological species-groups and a metabolite or group of metabolites synthesized. Thus, the whole set of analyses carried out in the present work supports the hypothesis that these small-spored Alternaria isolates from food belong to the same species. Identification at species level through classical morphology or modern molecular techniques does not seem to be a useful tool to predict toxicological risk in food matrices. The detection of any small-spored Alternaria from Section Alternaria (D.P. Lawr., Gannibal, Peever & B.M. Pryor 2013) in food implies a potential toxicological risk.

      PubDate: 2017-07-02T06:45:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.026
      Issue No: Vol. 257 (2017)
  • Whole transcriptome RNAseq analysis of Oenococcus oeni reveals distinct
           intra-specific expression patterns during malolactic fermentation,
           including genes involved in diacetyl metabolism
    • Authors: Peter R. Sternes; Peter J. Costello; Paul J. Chambers; Eveline J. Bartowsky; Anthony R. Borneman
      Pages: 216 - 224
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Peter R. Sternes, Peter J. Costello, Paul J. Chambers, Eveline J. Bartowsky, Anthony R. Borneman
      We report the first whole transcriptome RNAseq analysis of the wine-associated lactic acid bacterium Oenococcus oeni using a combination of reference-based mapping and de novo transcript assembly in three distinct strains during malolactic fermentation in Cabernet Sauvignon wine. Two of the strains (AWRIB551 and AWRIB552) exhibited similar transcriptomes relative to the third strain (AWRIB419) which was dissimilar by comparison. Significant intra-specific variation for genes related to glycolysis/gluconeogenesis, purine metabolism, aminoacyl-tRNA biosynthesis, ABC transporters and phosphotransferase systems was observed. Importantly, thirteen genes associated with the production of diacetyl, a commercially valuable aroma and flavour compound, were also found to be differentially expressed between the strains in a manner that correlated positively with total diacetyl production. This included a key strain-specific gene that is predicted to encode a l-lactate dehydrogenase that may enable l-lactic acid to be utilised as a precursor for the production of diacetyl. In conjunction with previous comparative genomic studies of O. oeni, this study progresses the understanding of genetic variations which contribute to the phenotypes of this industrially-important bacterium.

      PubDate: 2017-07-11T11:57:12Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.024
      Issue No: Vol. 257 (2017)
  • Porcine blood used as ingredient in meat productions may serve as a
           vehicle for hepatitis E virus transmission
    • Authors: Ingeborg L.A. Boxman; Claudia C.C. Jansen; Geke Hägele; Ans Zwartkruis-Nahuis; Jeroen Cremer; Harry Vennema; Aloys S.L. Tijsma
      Pages: 225 - 231
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Ingeborg L.A. Boxman, Claudia C.C. Jansen, Geke Hägele, Ans Zwartkruis-Nahuis, Jeroen Cremer, Harry Vennema, Aloys S.L. Tijsma
      The aim of the present study was to investigate whether the use of porcine blood(products) in food could be a risk for a hepatitis E virus (HEV) infection. HEV RNA was detected in 33/36 batches of (non-heated) liquid products and in 7/24 spray dried powder products. Contamination levels varied among the products, but were highest in liquid whole blood, plasma and fibrinogen reaching levels of 2.2×102 to 2.8×102 HEV genome copies per 0.2g. Sequence analyses revealed genotype 3 strains, of which two were 100% (493nt) identical to recently diagnosed HEV cases, although no direct epidemiological link was established. The industry provided information on processing of blood products in (ready-to-eat)-meat. From this, it was concluded that blood products as an ingredient of processed meat may not be sufficiently heated prior to consumption, and therefore could be a vehicle for transmission.

      PubDate: 2017-07-11T11:57:12Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.029
      Issue No: Vol. 257 (2017)
  • Quantitative contamination assessment of Escherichia coli in baby spinach
           primary production in Spain: Effects of weather conditions and
           agricultural practices
    • Authors: Ana Allende; Irene Castro-Ibáñez; Roland Lindqvist; María Isabel Gil; Mieke Uyttendaele; Liesbeth Jacxsens
      Pages: 238 - 246
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Ana Allende, Irene Castro-Ibáñez, Roland Lindqvist, María Isabel Gil, Mieke Uyttendaele, Liesbeth Jacxsens
      A quantitative microbial contamination model of Escherichia coli during primary production of baby spinach was developed. The model included only systematic contamination routes (e.g. soil and irrigation water) and it was used to evaluate the potential impact of weather conditions, agricultural practices as well as bacterial fitness in soil on the E. coli levels present in the crop at harvest. The model can be used to estimate E. coli contamination of baby spinach via irrigation water, via soil splashing due to irrigation water or rain events, and also including the inactivation of E. coli on plants due to solar radiation during a variable time of culturing before harvest. Seasonality, solar radiation and rainfall were predicted to have an important impact on the E. coli contamination. Winter conditions increased E. coli prevalence and levels when compared to spring conditions. As regards agricultural practices, both water quality and irrigation system slightly influenced E. coli levels on baby spinach. The good microbiological quality of the irrigation water (average E. coli counts in positive water samples below 1 log/100mL) could have influenced the differences observed among the tested agricultural practices (water treatment and irrigation system). This quantitative microbial contamination model represents a preliminary framework that assesses the potential impact of different factors and intervention strategies affecting E. coli concentrations at field level. Taking into account that E. coli strains may serve as a surrogate organism for enteric bacterial pathogens, obtained results on E. coli levels on baby spinach may be indicative of the potential behaviour of these pathogens under defined conditions.

      PubDate: 2017-07-11T11:57:12Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.027
      Issue No: Vol. 257 (2017)
  • Development of a novel multiplexed qPCR and Pyrosequencing method for the
           detection of human pathogenic yersiniae
    • Authors: M.C. Thomas; T.W. Janzen; G. Huscyzynsky; A. Mathews; K.K. Amoako
      Pages: 247 - 253
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): M.C. Thomas, T.W. Janzen, G. Huscyzynsky, A. Mathews, K.K. Amoako
      The purpose of this study was to develop a novel and robust molecular assay for the detection of human pathogenic yersiniae (i.e. Yersinia enterocolitica, Y. pseudotuberculosis and Y. pestis) in complex food samples. The assay combines multiplexed real-time PCR (qPCR) and Pyrosequencing for detecting and differentiating human pathogenic yersiniae with high confidence through sequence based confirmation. The assay demonstrated 100% specificity and inclusivity when tested against a panel of 14 Y. enterocolitica, 22 Y. pestis, 24 Y. pseudotuberculosis and a diverse selection of 17 other non-Yersinia bacteria. Pyrosequencing reads ranged from 28 to 40bp in length and had 94–100% sequence identity to the correct species in the GenBank nr database. Microbial enrichments of 48 ready-to-eat foods collected in the Greater Toronto Area from March 2014 to May 2014, including 46 fresh sprout and 2 salad products, were then tested using the assay. All samples were negative for Y. pestis and Y. pseudotuberculosis. Both salads (n=2) and 35% of sprout products (n=46) including 7.1% of alfalfa sprouts (n=14), 81% of bean sprouts (n=16), 12% of mixed sprouts (n=8) tested positive for Y. enterocolitica which was not detected in broccoli sprouts (n=5), onion sprouts (n=1), and pea sprouts (n=2). Cycle thresholds (Ct) of positive samples for Y. enterocolitica were between 23.0 and 37.9 suggesting post enrichment concentrations of approximately 1×102 to 1×106 Y. enterocolitica per 1mL of enriched broth. An internal amplification control which was coamplified with targets revealed PCR inhibition in five samples which was resolved following a one in ten dilution. Pyrosequencing of qPCR amplicons suggests monoclonality and revealed a single nucleotide polymorphism that is present in Y. enterocolitica biotype 1A suggesting low pathogenicity of the detected strains. This study is the first to combine Pyrosequencing and qPCR for the detection of human pathogenic yersiniae and is applicable to a broad range of complex samples including ready-to-eat food samples.

      PubDate: 2017-07-11T11:57:12Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.019
      Issue No: Vol. 257 (2017)
  • Variations in biofilm formation, desiccation resistance and Benzalkonium
           chloride susceptibility among Listeria monocytogenes strains isolated in
    • Authors: Marta J. Piercey; Timothy C. Ells; Andrew J. Macintosh; Lisbeth Truelstrup Hansen
      Pages: 254 - 261
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Marta J. Piercey, Timothy C. Ells, Andrew J. Macintosh, Lisbeth Truelstrup Hansen
      Listeria monocytogenes is a pathogenic foodborne microorganism noted for its ability to survive in the environment and food processing facilities. Survival may be related to the phenotype of individual strains including the ability to form biofilms and resist desiccation and/or sanitizer exposure. The objectives of this research were to compare 14 L. monocytogenes strains isolated from blood (3), food (6) and water (5) with respect to their benzalkonium chloride (BAC) sensitivity, desiccation resistance, and ability to form biofilm. Correlations were tested between those responses, and the presence of the SSI-1 (Stress Survival Islet) and LGI1/CC8 (Listeria Genomic Island 1 in a clonal complex 8 background) genetic markers. Genetic sequences from four strains representing different phenotypes were also probed for predicted amino acid differences in biofilm, desiccation, and membrane related genes. The water isolates were among the most desiccation susceptible strains, while strains exhibiting desiccation resistance harboured SSI-1 or both the SSI-1 and LGI1/CC8 markers. BAC resistance was greatest in planktonic LGI1/CC8 cells (relative to non-LGI1/CC8 cells), and higher BAC concentrations were also needed to inhibit the formation of biofilm by LGI1/CC8 strains during incubation for 48h and 6days compared to other strains. Formation of biofilm on stainless steel was not significantly (p>0.05) different among the strains. Analysis of genetic sequence data from desiccation and BAC sensitive (CP4 5-1, CP5 2-3, both from water), intermediate (Lm568, food) and desiccation and BAC resistant (08 5578, blood, human outbreak) strains led to the finding of amino acid differences in predicted functional protein domains in several biofilm, desiccation and peptidoglycan related genes (e.g., lmo0263, lmo0433, lmo0434, lmo0771, lmo0973, lmo1080, lmo1224, lmo1370, lmo1744, and lmo2558). Notably, the LGI1/CC8 strain 08-5578 had a frameshift mutation in lmo1370, a gene previously associated with desiccation resistance. In conclusion, the more desiccation and BAC resistant LGI1/CC8 isolates may pose a challenge for sanitation efforts.

      PubDate: 2017-07-21T12:25:18Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.025
      Issue No: Vol. 257 (2017)
  • RNAseq-based transcriptome comparison of Saccharomyces cerevisiae strains
           isolated from diverse fermentative environments
    • Authors: Clara Ibáñez; Roberto Pérez-Torrado; Miguel Morard; Christina Toft; Eladio Barrio; Amparo Querol
      Pages: 262 - 270
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Clara Ibáñez, Roberto Pérez-Torrado, Miguel Morard, Christina Toft, Eladio Barrio, Amparo Querol
      Transcriptome analyses play a central role in unraveling the complexity of gene expression regulation in Saccharomyces cerevisiae. This species, one of the most important microorganisms for humans given its industrial applications, shows an astonishing degree of genetic and phenotypic variability among different strains adapted to specific environments. In order to gain novel insights into the Saccharomyces cerevisiae biology of strains adapted to different fermentative environments, we analyzed the whole transcriptome of three strains isolated from wine, flor wine or mezcal fermentations. An RNA-seq transcriptome comparison of the different yeasts in the samples obtained during synthetic must fermentation highlighted the differences observed in the genes that encode mannoproteins, and in those involved in aroma, sugar transport, glycerol and alcohol metabolism, which are important under alcoholic fermentation conditions. These differences were also observed in the physiology of the strains after mannoprotein and aroma determinations. This study offers an essential foundation for understanding how gene expression variations contribute to the fermentation differences of the strains adapted to unequal fermentative environments. Such knowledge is crucial to make improvements in fermentation processes and to define targets for the genetic improvement or selection of wine yeasts.

      PubDate: 2017-07-21T12:25:18Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.001
      Issue No: Vol. 257 (2017)
  • Metabolic gene-targeted monitoring of non-starter lactic acid bacteria
           during cheese ripening
    • Authors: Alessia Levante; Francesca De Filippis; Antonietta La Storia; Monica Gatti; Erasmo Neviani; Danilo Ercolini; Camilla Lazzi
      Pages: 276 - 284
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Alessia Levante, Francesca De Filippis, Antonietta La Storia, Monica Gatti, Erasmo Neviani, Danilo Ercolini, Camilla Lazzi
      Long ripened cheeses, such as Grana Padano (GP), a Protected Designation of Origin (PDO) Italian cheese, harbor a viable microbiota mainly composed of non-starter lactic acid bacteria (NSLAB), which contribute to the final characteristics of cheese. The NSLAB species Lactobacillus rhamnosus, Lb. casei and Lb. paracasei are frequently found in GP, and form a closely related taxonomic group (Lb. casei group), making it difficult to distinguish the three species through 16S rRNA sequencing. SpxB, a metabolic gene coding for pyruvate oxidase in Lb. casei group, was recently used to distinguish the species within this bacterial group, both in pure cultures and in cheese, where it could provide an alternative energy source through the conversion of pyruvate to acetate. The aim of this work was to study the evolution of the metabolically active microbiota during different stages of GP ripening, targeting 16S rRNA to describe the whole microbiota composition, and spxB gene to monitor the biodiversity within the Lb. casei group. Furthermore, activation of pyruvate oxidase pathway was measured directly in cheese by reverse transcription real time PCR (RT–qPCR). The results showed that Lb. casei group dominates throughout the ripening and high-throughput sequencing of spxB allowed to identify four clusters inside the Lb. casei group. The dynamics of the sequence types forming the clusters were followed during ripening. Pyruvate oxidase pathway was expressed in cheese, showing a decreasing trend over ripening time. This work highlights how the composition of the microbiota in the early manufacturing stages influences the microbial dynamics throughout ripening, and how targeting of a metabolic gene can provide an insight into the activity of strains relevant for dairy products.

      PubDate: 2017-07-21T12:25:18Z
      DOI: 10.1016/j.ijfoodmicro.2017.07.002
      Issue No: Vol. 257 (2017)
  • Synergistic effects of some essential oils against fungal spoilage on pear
    • Authors: Mehdi Nikkhah; Maryam Hashemi; Mohammad B. Habibi Najafi; Reza Farhoosh
      Pages: 285 - 294
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Mehdi Nikkhah, Maryam Hashemi, Mohammad B. Habibi Najafi, Reza Farhoosh
      The development of natural protective agents as alternatives to chemical fungicides is currently in the spotlight. In the present investigation, chemical composition and antifungal activities of thyme, cinnamon, rosemary and marjoram essential oils (EO), as well as synergism of their possible double and triple combinations were investigated. The compositions of the oils were determined by GC/MS. For determination of antifungal activity against Penicillium expansum and Botrytis cinerea, a broth microdilution method was used. The possible interactions of some essential oil combinations were performed by the two and three-dimensional checkerboard assay and isobologram construction. An in vivo antifungal assay was performed by artificial wounding of pear fruits. The maximum antifungal activity was demonstrated by thyme and cinnamon oils which displayed lower MIC values whereas rosemary and marjoram oils with MIC range between 2500 and 10,000μg/mL exhibited weak antifungal activities against tested fungi. In synergy testing, some double combinations (thyme/cinnamon, thyme/rosemary, cinnamon/rosemary) were found to be synergistic (FICi≤0.5). The triple combination of thyme, cinnamon and rosemary was synergistic for B. cinerea and P. expansum (FICi values of 0.5 and 0.375, respectively); while combination of cinnamon, marjoram and thyme exhibited additive and synergistic effect against P. expansum (FIC=0.625) and B. cinerea (FIC=0.375) respectively. The usage of a mathematical Gompertz model in relation to fungal kinetics, showed that the model could be used to predict growth curves (R2 =0.993±0.05). For B. cinerea, Gompertz parameters for double and triple combination treatments showed significant increase in lag phase (1.92 and 2.92days, respectively) compared to single treatments. Increase lag time up to 2.82days (P<0.05) also observed in P. expansum treated by triple combination of EOs. Base on the results, the lowest maximum growth rate (0.37mm/day) was observed in B. cinerea treated by triple combination of thyme, cinnamon and rosemary. The in vivo test also demonstrated considerable inhibitory effects of EO combination treatments. Average lesion diameter of pears treated with triple combination of cinnamon/rosemary/thyme (78, 1250, 39μg/mL) was 6mm and 8mm against B. cinerea and P. expansum respectively, in 10days at 25°C. Results also showed that double combination of thyme/cinnamon (78, 156μg/mL) has more inhibitory effect than single EO treatments.

      PubDate: 2017-08-07T08:35:02Z
      DOI: 10.1016/j.ijfoodmicro.2017.06.021
      Issue No: Vol. 257 (2017)
  • Inside Front Cover - Editorial Board
    • Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257

      PubDate: 2017-08-17T10:24:40Z
  • Global transcriptional response of Escherichia coli MG1655 cells exposed
           to the oxygenated monoterpenes citral and carvacrol
    • Authors: Beatriz Chueca; Elisa Rafael Diego
      Abstract: Publication date: 18 September 2017
      Source:International Journal of Food Microbiology, Volume 257
      Author(s): Beatriz Chueca, Elisa Pérez-Sáez, Rafael Pagán, Diego García-Gonzalo
      DNA microarrays were used to study the mechanism of bacterial inactivation by carvacrol and citral. After 10-min treatments of Escherichia coli MG1655 cells with 100 and 50ppm of carvacrol and citral, 76 and 156 genes demonstrated significant transcriptional differences (p ≤0.05), respectively. Among the up-regulated genes after carvacrol treatment, we found gene coding for multidrug efflux pumps (acrA, mdtM), genes related to phage shock response (pspA, pspB, pspC, pspD, pspF and pspG), biosynthesis of arginine (argC, argG, artJ), and purine nucleotides (purC, purM). In citral-treated cells, transcription of purH and pyrB and pyrI was 2 times higher. Deletion of several differentially expressed genes confirmed the role of ygaV, yjbO, pspC, sdhA, yejG and ygaV in the mechanisms of E. coli inactivation by carvacrol and citral. These results would indicate that citral and carvacrol treatments cause membrane damage and activate metabolism through the production of nucleotides required for DNA and RNA synthesis and metabolic processes. Comparative transcriptomics of the response of E. coli to a heat treatment, which caused a significant change of the transcription of 1422 genes, revealed a much weaker response to both individual constituents of essential oils (ICs).·Thus, inactivation by citral or carvacrol was not multitarget in nature.

      PubDate: 2017-06-22T09:32:27Z
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