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  Subjects -> BIOLOGY (Total: 2985 journals)
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MICROBIOLOGY (253 journals)                  1 2 | Last

Showing 1 - 200 of 253 Journals sorted alphabetically
Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 4)
Addiction Genetics     Open Access   (Followers: 5)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 21)
Advances in Microbiology     Open Access   (Followers: 21)
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: 19)
American Journal of Microbiological Research     Open Access   (Followers: 2)
American Journal of Microbiology     Open Access   (Followers: 15)
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: 9)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 37)
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: 61)
Aquatic Microbial Ecology     Hybrid Journal   (Followers: 2)
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: 1)
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: 4)
Cell Biology : Research & Therapy     Hybrid Journal   (Followers: 4)
Cell Host & Microbe     Full-text available via subscription   (Followers: 17)
Cell Medicine     Open Access   (Followers: 3)
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: 8)
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: 18)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 7)
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: 1)
Current Issues in Molecular Biology     Open Access   (Followers: 2)
Current Microbiology     Hybrid Journal   (Followers: 11)
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: 11)
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: 4)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 14)
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: 8)
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: 16)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 4)
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: 4)
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  
Indian Journal of Microbiology     Hybrid Journal   (Followers: 2)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 4)
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: 12)
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: 14)
Journal of Bacteriology     Hybrid Journal   (Followers: 28)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 3)
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: 4)
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: 15)
Journal of Medical Microbiology     Full-text available via subscription   (Followers: 4)
Journal of Microbiological Methods     Hybrid Journal   (Followers: 2)
Journal of Microbiology     Hybrid Journal   (Followers: 8)
Journal of Microbiology and Antimicrobials     Open Access   (Followers: 2)
Journal of Microbiology Research     Open Access   (Followers: 4)
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: 13)
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: 6)
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: 13)
Microbiology (SGM)     Full-text available via subscription   (Followers: 17)
Microbiology and Immunology     Hybrid Journal   (Followers: 10)
Microbiology and Molecular Biology Reviews     Hybrid Journal   (Followers: 24)
Microbiology Australia     Hybrid Journal  
Microbiology Discovery     Open Access   (Followers: 1)
Microbiology Indonesia     Open Access  
Microbiology Research     Open Access   (Followers: 7)
MicrobiologyOpen     Open Access   (Followers: 2)
Microbiome     Hybrid Journal   (Followers: 7)
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: 2)
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: 31)
Molecular Oral Microbiology     Partially Free   (Followers: 3)
Molecular Systems Biology     Open Access   (Followers: 9)
Molecular Therapy - Methods & Clinical Development     Open Access  
mSphere     Open Access   (Followers: 1)

        1 2 | Last

Journal Cover International Journal of Food Microbiology
  [SJR: 1.64]   [H-I: 142]   [12 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0168-1605
   Published by Elsevier Homepage  [3042 journals]
  • 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 3.2.1.23) 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)
       
  • Aflatoxin B1 inhibition in Aspergillus flavus by Aspergillus niger through
           down-regulating expression of major biosynthetic genes and AFB1
           degradation by atoxigenic A. flavus
    • Authors: Fuguo Xing; Limin Wang; Xiao Liu; Jonathan Nimal Selvaraj; Yan Wang; Yueju Zhao; Yang Liu
      Pages: 1 - 10
      Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256
      Author(s): Fuguo Xing, Limin Wang, Xiao Liu, Jonathan Nimal Selvaraj, Yan Wang, Yueju Zhao, Yang Liu
      Twenty Aspergillus niger strains were isolated from peanuts and 14 strains were able to completely inhibit AFB1 production with co-cultivation. By using a Spin-X centrifuge system, it was confirmed that there are some soluble signal molecules or antibiotics involved in the inhibition by A. niger, although they are absent during the initial 24h of A. flavus growth when it is sensitive to inhibition. In A. flavus, 19 of 20 aflatoxin biosynthetic genes were down-regulated by A. niger. Importantly, the expression of aflS was significantly down-regulated, resulting in a reduction of AflS/AflR ratio. The results suggest that A. niger could directly inhibit AFB1 biosynthesis through reducing the abundance of aflS to aflR mRNAs. Interestingly, atoxigenic A. flavus JZ2 and GZ15 effectively degrade AFB1. Two new metabolites were identified and the key toxic lactone and furofuran rings both were destroyed and hydrogenated, meaning that lactonase and reductase might be involved in the degradation process.

      PubDate: 2017-06-02T02:57:22Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.013
      Issue No: Vol. 256 (2017)
       
  • Lactic acid bacteria involved in cocoa beans fermentation from Ivory
           Coast: Species diversity and citrate lyase production
    • Authors: Hadja D. Ouattara; Honoré G. Ouattara; Michel Droux; Sylvie Reverchon; William Nasser; Sébastien L. Niamke
      Pages: 11 - 19
      Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256
      Author(s): Hadja D. Ouattara, Honoré G. Ouattara, Michel Droux, Sylvie Reverchon, William Nasser, Sébastien L. Niamke
      Microbial fermentation is an indispensable process for high quality chocolate from cocoa bean raw material. lactic acid bacteria (LAB) are among the major microorganisms responsible for cocoa fermentation but their exact role remains to be elucidated. In this study, we analyzed the diversity of LAB in six cocoa producing regions of Ivory Coast. Ribosomal 16S gene sequence analysis showed that Lactobacillus plantarum and Leuconostoc mesenteroides are the dominant LAB species in these six regions. In addition, other species were identified as the minor microbial population, namely Lactobacillus curieae, Enterococcus faecium, Fructobacillus pseudoficulneus, Lactobacillus casei, Weissella paramesenteroides and Weissella cibaria. However, in each region, the LAB microbial population was composed of a restricted number of species (maximum 5 species), which varied between the different regions. LAB implication in the breakdown of citric acid was investigated as a fundamental property for a successful cocoa fermentation process. High citrate lyase producer strains were characterized by rapid citric acid consumption, as revealed by a 4-fold decrease in citric acid concentration in the growth medium within 12h, concomitant with an increase in acetic acid and lactic acid concentration. The production of citrate lyase was strongly dependent on environmental conditions, with optimum production at acidic pH (pH<5), and moderate temperature (30–40°C), which corresponds to conditions prevailing in the early stage of natural cocoa fermentation. This study reveals that one of the major roles of LAB in the cocoa fermentation process involves the breakdown of citric acid during the early stage of cocoa fermentation through the activity of citrate lyase.

      PubDate: 2017-06-02T02:57:22Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.008
      Issue No: Vol. 256 (2017)
       
  • Next generation sequencing-based multigene panel for high throughput
           detection of food-borne pathogens
    • Authors: Chiara Ferrario; Gabriele Andrea Lugli; Maria Cristina Ossiprandi; Francesca Turroni; Christian Milani; Sabrina Duranti; Leonardo Mancabelli; Marta Mangifesta; Giulia Alessandri; Douwe van Sinderen; Marco Ventura
      Pages: 20 - 29
      Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256
      Author(s): Chiara Ferrario, Gabriele Andrea Lugli, Maria Cristina Ossiprandi, Francesca Turroni, Christian Milani, Sabrina Duranti, Leonardo Mancabelli, Marta Mangifesta, Giulia Alessandri, Douwe van Sinderen, Marco Ventura
      Contamination of food by chemicals or pathogenic bacteria may cause particular illnesses that are linked to food consumption, commonly referred to as foodborne diseases. Bacteria are present in/on various foods products, such as fruits, vegetables and ready-to-eat products. Bacteria that cause foodborne diseases are known as foodborne pathogens (FBPs). Accurate detection methods that are able to reveal the presence of FBPs in food matrices are in constant demand, in order to ensure safe foods with a minimal risk of causing foodborne diseases. Here, a multiplex PCR-based Illumina sequencing method for FBP detection in food matrices was developed. Starting from 25 bacterial targets and 49 selected PCR primer pairs, a primer collection called foodborne pathogen – panel (FPP) consisting of 12 oligonucleotide pairs was developed. The FPP allows a more rapid and reliable identification of FBPs compared to classical cultivation methods. Furthermore, FPP permits sensitive and specific FBP detection in about two days from food sample acquisition to bioinformatics-based identification. The FPP is able to simultaneously identify eight different bacterial pathogens, i.e. Listeria monocytogenes, Campylobacter jejuni, Campylobacter coli, Salmonella enterica subsp. enterica serovar enteritidis, Escherichia coli, Shigella sonnei, Staphylococcus aureus and Yersinia enterocolitica, in a given food matrix at a threshold contamination level of 101 cell/g. Moreover, this novel detection method may represent an alternative and/or a complementary approach to PCR-based techniques, which are routinely used for FBP detection, and could be implemented in (parts of) the food chain as a quality check.

      PubDate: 2017-06-02T02:57:22Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.001
      Issue No: Vol. 256 (2017)
       
  • Interactions between water activity and temperature on the Aspergillus
           flavus transcriptome and aflatoxin B1 production
    • Authors: Angel Medina; Matthew K. Gilbert; Brian M. Mack; Gregory R. OBrian; Alicia Rodríguez; Deepak Bhatnagar; Gary Payne; Naresh Magan
      Pages: 36 - 44
      Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256
      Author(s): Angel Medina, Matthew K. Gilbert, Brian M. Mack, Gregory R. OBrian, Alicia Rodríguez, Deepak Bhatnagar, Gary Payne, Naresh Magan
      Effects of Aspergillus flavus colonization of maize kernels under different water activities (aw; 0.99 and 0.91) and temperatures (30, 37°C) on (a) aflatoxin B1 (AFB1) production and (b) the transcriptome using RNAseq were examined. There was no significant difference (p =0.05) in AFB1 production at 30 and 37°C and 0.99 aw. However, there was a significant (p =0.05) increase in AFB1 at 0.91 aw at 37°C when compared with 30°C/0.99 aw. Environmental stress effects using gene ontology enrichment analysis of the RNA-seq results for increasing temperature at 0.99 and 0.91 aw showed differential expression of 2224 and 481 genes, respectively. With decreasing water availability, 4307 were affected at 30°C and 702 genes at 37°C. Increasing temperature from 30 to 37°C at both aw levels resulted in 12 biological processes being upregulated and 9 significantly downregulated. Decreasing aw at both temperatures resulted in 22 biological processes significantly upregulated and 25 downregulated. The interacting environmental factors influenced functioning of the secondary metabolite gene clusters for aflatoxins and cyclopiazonic acid (CPA). An elevated number of genes were co-regulated by both aw and temperature. An interaction effect for 4 of the 25 AFB1 genes, including regulatory and transcription activators occurred. For CPA, all 5 biosynthetic genes were affected by aw stress, regardless of temperature. The molecular regulation of A. flavus in maize is discussed.

      PubDate: 2017-06-07T12:19:09Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.020
      Issue No: Vol. 256 (2017)
       
  • Persistent Listeria monocytogenes strains isolated from mussel production
           facilities form more biofilm but are not linked to specific genetic
           markers
    • Authors: Jessika Nowak; Cristina D. Cruz; Marcel Tempelaars; Tjakko Abee; Arnoud H.M. van Vliet; Graham C. Fletcher; Duncan Hedderley; Jon Palmer; Steve Flint
      Pages: 45 - 53
      Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256
      Author(s): Jessika Nowak, Cristina D. Cruz, Marcel Tempelaars, Tjakko Abee, Arnoud H.M. van Vliet, Graham C. Fletcher, Duncan Hedderley, Jon Palmer, Steve Flint
      Contamination of mussels with the human pathogen Listeria monocytogenes occurs during processing in the factory, possibly from bacteria persisting in the factory's indoor and outdoor areas. In this study, a selection of persistent (n=8) and sporadic (n=8) L. monocytogenes isolates associated with mussel-processing premises in New Zealand were investigated for their phenotypic and genomic characteristics. To identify traits that favour or contribute to bacterial persistence, biofilm formation, heat resistance, motility and recovery from dry surfaces were compared between persistent and sporadic isolates. All isolates exhibited low biofilm formation at 20°C, however, at 30°C persistent isolates showed significantly higher biofilm formation after 48h using cell enumeration and near significant difference using the crystal violet assay. All 16 isolates were motile at 20°C and 30°C and motility was fractionally higher for sporadic isolates, but no significant difference was observed. We found persistent isolates tend to exhibit greater recovery after incubation on dry surfaces compared to sporadic isolates. Two of the three most heat-resistant isolates were persistent, while four of five isolates lacking heat resistance were sporadic isolates. Comparison of genome sequences of persistent and sporadic isolates showed that there was no overall clustering of persistent or sporadic isolates, and that differences in prophages and plasmids were not associated with persistence. Our results suggest a link between persistence and biofilm formation, which is most likely multifactorial, combining subtle phenotypic and genotypic differences between isolates.

      PubDate: 2017-06-07T12:19:09Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.024
      Issue No: Vol. 256 (2017)
       
  • Lactobacillus plantarum and Streptococcus thermophilus as starter cultures
           for a donkey milk fermented beverage
    • Authors: Barbara Turchi; Francesca Pedonese; Beatrice Torracca; Filippo Fratini; Simone Mancini; Alessia Galiero; Benedetta Montalbano; Domenico Cerri; Roberta Nuvoloni
      Pages: 54 - 61
      Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256
      Author(s): Barbara Turchi, Francesca Pedonese, Beatrice Torracca, Filippo Fratini, Simone Mancini, Alessia Galiero, Benedetta Montalbano, Domenico Cerri, Roberta Nuvoloni
      Donkey milk is recently gaining attention due to its nutraceutical properties. Its low casein content does not allow caseification, so the production of a fermented milk would represent an alternative way to increase donkey milk shelf life. The aim of this study was to investigate the possibility of employing selected Streptococcus thermophilus and Lactobacillus plantarum isolates for the production of a novel donkey milk fermented beverage. Lysozyme resistance and the ability to acidify donkey milk were chosen as main selection parameters. Different fermented beverages (C1–C9) were produced, each with a specific combination of isolates, and stored at refrigerated conditions for 35days. The pH values and viability of the isolates were weekly assessed. In addition, sensory analysis was performed. Both S. thermophilus and L. plantarum showed a high degree of resistance to lysozyme with a Minimum Bactericidal Concentration>6.4mg/mL for 100% of S. thermophilus and 96% of L. plantarum. S. thermophilus and L. plantarum showed the ability to acidify donkey milk in 24h at 37°C, with an average ΔpH value of 2.91±0.16 and 1.78±0.66, respectively. Four L. plantarum and two S. thermophilus were chosen for the production of fermented milks. Those containing the association S. thermophilus/L. plantarum (C1–C4) reached a pH lower than 4.5 after 18h of fermentation and showed microbial loads higher than 7.00logcfu/mL until the end of the storage period. Moreover, comparing the microbial loads of samples containing both species and those containing S. thermophilus alone (C5), we highlighted the ability of L. plantarum to stimulate S. thermophilus replication. This boosted replication of S. thermophilus allowed to reach an appropriate pH in a time frame fitting the production schedule. This was not observed for samples containing a single species (C5–C9). Thus, L. plantarum strains seem to be good candidates in the production of a novel type of fermented milk, not only for their probiotic potential, but also for the enhancing effect on S. thermophilus growth.

      PubDate: 2017-06-12T12:33:19Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.022
      Issue No: Vol. 256 (2017)
       
  • High-throughput metataxonomic characterization of the raw milk microbiota
           identifies changes reflecting lactation stage and storage conditions
    • Authors: Conor J. Doyle; David Gleeson; Paul W. O'Toole; Paul D. Cotter
      Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255
      Author(s): Conor J. Doyle, David Gleeson, Paul W. O'Toole, Paul D. Cotter
      Low temperature is used to control the growth of bacteria in milk, both pre- and post-pasteurization. As the duration of refrigerated storage extends, psychrotrophs dominate the milk microbiota, that can produce heat stable lipases which negatively impact the organoleptic qualities of milk. Here we examine the influence that refrigeration temperature (2°C, 4°C and 6°C) and storage duration (96h) have on the microbiota composition (16S profiling) of raw bulk tank milk (BTM). To reflect a proposed change to current farming practices, raw milk was blended after each milking (8 milkings) and stored for five consecutive days in each temperature-specific tank. Here 16S rRNA-based microbiota compositional analysis was performed after milk was collected on day 1 and again after the final addition of milk at day 5. In addition to assessing the impact of the duration and temperature of storage, the influence of lactation stage, i.e. mid- versus late-lactation, on the microbiota of the blended BTM was also examined. Overall, both temperature and length of storage had surprisingly little influence on the raw milk microbiota, other than an increase in proportions of Gammaproteobacteria in the blended milk samples collected after pooling on day 5, and in samples stored at 6°C. However, lactation stage had a considerable influence on microbiota composition, with milk from mid-lactation containing higher proportions of Bacteroides, Faecalibacterium, Campylobacter and Rhodanobacter, and late-lactation milk containing higher proportions of Actinobacteria. Overall, the study demonstrates that current temperature and storage duration practises impact the microbiota of raw milk, but these impacts are modest relative to the more considerable differences between mid and late-lactation milk.

      PubDate: 2017-05-27T18:06:01Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.019
      Issue No: Vol. 255 (2017)
       
  • Impact of thistle rennet from Carlina acanthifolia All. subsp.
           acanthifolia on bacterial diversity and dynamics of a specialty Italian
           raw ewes' milk cheese
    • Authors: Federica Cardinali; Andrea Osimani; Manuela Taccari; Vesna Milanović; Cristiana Garofalo; Francesca Clementi; Serena Polverigiani; Silvia Zitti; Nadia Raffaelli; Massimo Mozzon; Roberta Foligni; Elena Franciosi; Kieran Tuohy; Lucia Aquilanti
      Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255
      Author(s): Federica Cardinali, Andrea Osimani, Manuela Taccari, Vesna Milanović, Cristiana Garofalo, Francesca Clementi, Serena Polverigiani, Silvia Zitti, Nadia Raffaelli, Massimo Mozzon, Roberta Foligni, Elena Franciosi, Kieran Tuohy, Lucia Aquilanti
      Caciofiore della Sibilla is an Italian specialty soft cheese manufactured with Sopravissana raw ewes' milk and thistle rennet prepared with young fresh leaves and stems of Carlina acanthifolia All. subsp. acanthifolia, according to an ancient tradition deeply rooted in the territory of origin (mountainous hinterland of the Marche region, Central Italy). In this study, the impact of thistle rennet on the bacterial dynamics and diversity of Caciofiore della Sibilla cheese was investigated by applying a polyphasic approach based on culture and DNA-based techniques (Illumina sequencing and PCR-DGGE). A control cheese manufactured with the same batch of ewes' raw milk and commercial animal rennet was analyzed in parallel. Overall, a large number of bacterial taxa were identified, including spoilage, environmental and pro-technological bacteria, primarily ascribed to Lactobacillales. Thistle rennet was observed clearly to affect the early bacterial dynamics of Caciofiore della Sibilla cheese with Lactobacillus alimentarius/paralimentarius and Lactobacillus plantarum/paraplantarum/pentosus being detected in the phyllosphere of C. acanthifolia All., thistle rennet and curd obtained with thistle rennet. Other bacterial taxa, hypothetically originating from the vegetable coagulant (Enterococcus faecium, Lactobacillus brevis, Lactobacillus delbrueckii, Leuconostoc mesenteroides/pseudomesenteroides), were exclusively found in Caciofiore della Sibilla cheese by PCR-DGGE. At the end of the maturation period, Illumina sequencing demonstrated that both cheeses were dominated by Lactobacillales; however curd and cheese produced with thistle rennet were co-dominated by Lactobacillus and Leuconostoc, whereas Lactoccous prevailed in curd and cheese produced with commercial animal rennet followed by Lactobacillus. Differences in the bacterial composition between the two cheeses at the end of their maturation period were confirmed by PCR-DGGE analysis.

      PubDate: 2017-05-27T18:06:01Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.018
      Issue No: Vol. 255 (2017)
       
  • Purification of leucocin A for use on wieners to inhibit Listeria
           monocytogenes in the presence of spoilage organisms
    • Authors: Danielle R. Balay; Ramana V. Dangeti; Kamaljit Kaur; Lynn M. McMullen
      Pages: 25 - 31
      Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255
      Author(s): Danielle R. Balay, Ramana V. Dangeti, Kamaljit Kaur, Lynn M. McMullen
      The aims of this study were to improve the method for purification of leucocin A to increase yield of peptide and to evaluate the efficacy of leucocin A and an analogue of leucocin A (leucocin N17L) to inhibit the growth of Listeria monocytogenes on wieners in the presence of spoilage organisms. Leucocin A was produced by Leuconostoc gelidum UAL187 and purified with a five-fold increase in yield; leucocin N17L was synthesized replacing asparagine at residue 17 with leucine. Five strains of L. monocytogenes associated with foodborne illness were used to assess bacteriocin efficacy in vitro and in situ. Minimum inhibitory concentrations could not be determined in broth; however, on agar the minimum inhibitory concentrations ranged from 11.7–62.5μM and 62.5–>500μM for leucocin A and leucocin N17L, respectively. Leucocin N17L was less effective than the native bacteriocin at controlling the growth of L. monocytogenes. The inactivation profiles of L. monocytogenes in broth in the presence of leucocin A suggested each isolate had different levels of resistance to the bacteriocin as determined by the initial bactericidal effect. The formation of spontaneously resistance subpopulations were also observed for each strain of L. monocytogenes. In situ, wieners were inoculated with the spoilage organisms, Carnobacterium divergens and Brochothrix thermosphacta, followed by surface application of purified leucocin A, and inoculated with a cocktail of L. monocytogenes. Wieners were vacuum packaged and stored at 7°C for 16d. Leucocin A reduced the counts L. monocytogenes on wieners during storage, regardless of the presence of C. divergens. B. thermosphacta was unaffected by the presence of leucocin A on wieners over the duration of storage. This study suggests that leucocin A may be beneficial to industry as a surface application on wieners to help reduce L. monocytogenes counts due to post-processing contamination even in the presence of spoilage organisms. However, further investigation on the ability of L. monocytogenes to form spontaneous resistance to class II bacteriocins on food matrices during prolonged storage is warranted.

      PubDate: 2017-06-02T02:57:22Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.016
      Issue No: Vol. 255 (2017)
       
  • Characterization of the peptide fraction from digested Parmigiano Reggiano
           cheese and its effect on growth of lactobacilli and bifidobacteria
    • Authors: Benedetta Bottari; Andrea Quartieri; Barbara Prandi; Stefano Raimondi; Alan Leonardi; Maddalena Rossi; Alessandro Ulrici; Monica Gatti; Stefano Sforza; Marco Nocetti; Alberto Amaretti
      Pages: 32 - 41
      Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255
      Author(s): Benedetta Bottari, Andrea Quartieri, Barbara Prandi, Stefano Raimondi, Alan Leonardi, Maddalena Rossi, Alessandro Ulrici, Monica Gatti, Stefano Sforza, Marco Nocetti, Alberto Amaretti
      Parmigiano Reggiano (PR) is a raw-milk, hard cooked, long-ripened cheese of high quality and nutritional value. Long ripening times allow for extensive proteolysis of milk proteins to yield a number of peptides, some of which have potential healthy bioactive properties. This study aimed to: i) determine the peptide profile of PR cheese subjected to simulated gastrointestinal transit; ii) evaluate in vitro whether the peptides could support growth of beneficial microbial groups of the gut microbiota. PR samples were subjected to in vitro digestion, simulating oral, gastric, and duodenal transit. Liquid chromatography coupled with tandem mass spectrometry revealed that digestion caused the disappearance of the serum proteins and most of the original peptides, while 71 new peptides were found, all ranging from 2 to 24 residues. The digests were given as sole nitrogen source to pure cultures of Bifidobacterium (27 strains) and Lactobacillus (30 strains), and to bioreactor batch cultures of human gut microbiota. Most of bifidobacteria and lactobacilli grew more abundantly on PR digests than on the control peptone, and exhibited strain- or species-specific peptide preferences, as evidenced by principal component analysis. Bifidobacteria generally consumed a greater amount of peptides than lactobacilli, in terms of both the mean peptide consumption and the number of peptides consumed. For bifidobacteria, peptide preferences were very diverse, but a core of 10 peptides with 4 or 5 residues were consumed by all the strains. Lactobacilli behaved more homogenously and consumed nearly only the same 6 peptides, mostly dipeptides. The peptide preferences of the different groups of bifidobacteria and lactobacilli could not be ascribed to features such as the length of the peptide or the abundance of residues with peculiar properties (hydrophobicity, polarity, charge) and likely depend on specific proteases and/or peptide transporters preferentially recognizing specific sequence motifs. The cultures of human colonic microbiota confirmed that PR digest promoted the growth of commensal bifidobacteria. This study demonstrated that peptides derived from simulated gastrointestinal digestion of PR supported the growth of most lactobacilli and bifidobacteria.

      PubDate: 2017-06-02T02:57:22Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.015
      Issue No: Vol. 255 (2017)
       
  • Evaluating the feasibility of fermentation starter inoculated with
           Bacillus amyloliquefaciens for improving acetoin and tetramethylpyrazine
           in Baoning bran vinegar
    • Authors: Liqiang Zhang; Jun Huang; Rongqing Zhou; Chongde Wu
      Pages: 42 - 50
      Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255
      Author(s): Liqiang Zhang, Jun Huang, Rongqing Zhou, Chongde Wu
      Fermentation starters (Daqu) used in present study included traditional herb Daqu (C Daqu), modified Daqu without herbs (M Daqu) and S Daqu fermented by inoculating acetoin and tetramethylpyrazine high-producing bacterium Bacillus amyloliquefaciens into M Daqu. To evaluate the feasibility of S Daqu combined with M Daqu applied for improving contents of acetoin and tetramethylpyrazine in Baoning bran vinegar without remarkably changing the original microbial community and the other volatiles contents compared with C Daqu, vinegar Pei C, M, M1, M2 and S were correspondingly prepared in lab scale using C Daqu, M Daqu, M1 Daqu (S Daqu: M Daqu =1:9, w/w), M2 Daqu (S Daqu: M Daqu =5:5) and S Daqu. PCR-DGGE suggested that Bacillus, Lactobacillus, Oceanobacillus, Acetobacter, Pichia, Geotrichum and Trichoderma were dominant microbes. Microbial community of M were similar with M1, while that of the others were similar. Differences in physicochemical properties among samples may be ascribed to different enzymes activities of Daqu and bioactivities of microbial metabolism during fermentation. Moreover, total contents of organic acids in M, M1, M2 and S increased by 33.10%, 25.77%, 4.32% and 7.74% relative to C, respectively. Volatiles and PLS-DA analysis suggested that volatile profiles of M were similar with M1, that of M2 were similar with C, while that of S were significantly different with the others. Both M2 Daqu and S Daqu facilitated the formation of acetoin and tetramethylpyrazine. However, M2 Daqu was more efficient for enhancing acetoin and tetramethylpyrazine contents by 191.84% and 123.17% respectively, without significantly changing the other volatiles contents.

      PubDate: 2017-06-02T02:57:22Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.021
      Issue No: Vol. 255 (2017)
       
  • Keeping it cool: Survival of Giardia cysts and Cryptosporidium oocysts on
           lettuce leaves
    • Authors: Kjersti Selstad Utaaker; Eystein Skjerve; Lucy J. Robertson
      Pages: 51 - 57
      Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255
      Author(s): Kjersti Selstad Utaaker, Eystein Skjerve, Lucy J. Robertson
      Fresh produce has been recognized as a vehicle for transmission of protozoan parasites for many years, and there are numerous publications regarding their occurrence on such foodstuffs, indicating their potential importance as foodborne parasites. Nevertheless, few studies have been published regarding the effectiveness of this transmission route, and whether contamination is likely to result in transmission. The purpose of this study was to assess the viability of Cryptosporidium oocysts and Giardia cysts, two protozoa associated with both waterborne and foodborne transmission, by spiking fresh produce (lettuce leaves) with viable transmission stages and determining changes in viability. These investigations were performed under different conditions and over time spans that may be used in a regular household; a fridge at 4°C, under ambient temperatures exposed to natural cycles of light during night and day, and inside a cupboard to ensure no light exposure, for a duration of up to two weeks, or as long as the produce remained visually palatable. The major finding from this study is that whereas both Cryptosporidium oocysts and Giardia cysts survive well when kept moist and refrigerated, survival of Giardia cysts was abrogated on lettuce at room temperature. Indeed, almost 50% die-off of Giardia cysts was recorded within the first 24h. Cryptosporidium oocysts had a stable viability throughout the experiment under all the conditions investigated, indicating that fresh produce is a suitable transmission vehicle for Cryptosporidium, even if contamination occurs on-farm and the parasites are exposed to non-favourable storage conditions, as may be common in developing countries. Giardia cysts were not as robust as Cryptosporidium oocysts, and would be probably unlikely to survive under ambient storage conditions on-farm, during sale, or at home. However, if kept refrigerated, then some contaminating Giardia cysts may remain viable and therefore may pose a threat to the consumer. Thus, as the cold chain for transport and storage of fresh produce improves, it is important that similar improvements are implemented to reduce the contamination of fresh produce with parasite transmission stages.

      PubDate: 2017-06-02T02:57:22Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.009
      Issue No: Vol. 255 (2017)
       
  • Evaluation of different PCR primers for denaturing gradient gel
           electrophoresis (DGGE) analysis of fungal community structure in
           traditional fermentation starters used for Hong Qu glutinous rice wine
    • Authors: Xu-Cong Lv; Ya-Jun Jiang; Jie Liu; Wei-Ling Guo; Zhi-Bin Liu; Wen Zhang; Ping-Fan Rao; Li Ni
      Pages: 58 - 65
      Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255
      Author(s): Xu-Cong Lv, Ya-Jun Jiang, Jie Liu, Wei-Ling Guo, Zhi-Bin Liu, Wen Zhang, Ping-Fan Rao, Li Ni
      Denaturing gradient gel electrophoresis (DGGE) has become a widely used tool to examine microbial community structure. However, when DGGE is applied to evaluate the fungal community of traditional fermentation starters, the choice of hypervariable ribosomal RNA gene regions is still controversial. In the current study, several previously published fungal PCR primer sets were compared and evaluated using PCR-DGGE, with the purpose of screening a suitable primer set to study the fungal community of traditional fermentation starters for Hong Qu glutinous rice wine. Firstly, different primer sets were used to amplify different hypervariable regions from pure fungal cultures. Except NS1/FR1+ and ITS1fGC/ITS4, other primer sets (NL1+/LS2R, NL3A/NL4GC, FF390/FR1+, NS1/GCFung, NS3+/YM951r and ITS1fGC/ITS2r) amplified the target DNA sequences successfully. Secondly, the selected primer sets were further evaluated based on their resolution to distinguish different fungal cultures through DGGE fingerprints. Three primer sets (NL1+/LS2R, NS1/GCFung and ITS1fGC/ITS2r) were finally selected for investigating the fungal community structure of different traditional fermentation starters for Hong Qu glutinous rice wine. The internal transcribed spacer (ITS) region amplified by ITS1fGC/ITS2r, which is more hypervariable than the 18S rRNA gene and 26S rRNA gene, provides an excellent tool to separate amplification products of different fungal species. Results indicated that PCR-DGGE profile using ITS1fGC/ITS2r showed more abundant fungal species than that using NL1+/LS2R and NS1/GCFung. Therefore, ITS1fGC/ITS2r is the most suitable primer set for PCR-DGGE analysis of fungal community structure in traditional fermentation starters for Hong Qu glutinous rice wine. DGGE profiles based on ITS1fGC/ITS2r revealed the presence of twenty-four fungal species in traditional fermentation starter. A significant difference of fungal community can be observed directly from DGGE fingerprints and principal component analysis. The statistical analysis results based on the band intensities of fungal DGGE profile showed that Saccharomyces cerevisiae, Saccharomycopsis fibuligera, Rhizopus oryzae, Monascus purpureus and Aspergillus niger were the dominant fungal species. In conclusion, the comparison of several primer sets for fungal PCR-DGGE would be useful to enrich our knowledge of the fungal community structures associated with traditional fermentation starters, which may facilitate the development of better starter cultures for manufacturing Chinese Hong Qu glutinous rice wine.

      PubDate: 2017-06-07T12:19:09Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.010
      Issue No: Vol. 255 (2017)
       
  • Wine yeasts identification by MALDI-TOF MS: Optimization of the
           preanalytical steps and development of an extensible open-source platform
           for processing and analysis of an in-house MS database
    • Authors: Cristina Gutiérrez; M. Ángeles Gómez-Flechoso; Ignacio Belda; Javier Ruiz; Nour Kayali; Luis Polo; Antonio Santos
      Pages: 1 - 10
      Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254
      Author(s): Cristina Gutiérrez, M. Ángeles Gómez-Flechoso, Ignacio Belda, Javier Ruiz, Nour Kayali, Luis Polo, Antonio Santos
      Saccharomyces cerevisiae is the most important yeast species for the production of wine and other beverages. In addition, nowadays, researchers and winemakers are aware of the influence of non-Saccharomyces in wine aroma complexity. Due to the high microbial diversity associated to several agro-food processes, such as winemaking, developing fast and accurate methods for microbial identification is demanded. In this context, MALDI-TOF MS mass fingerprint provides reliable tool for fast biotyping and classification of microorganisms. However, there is no versatile and standardized method for fungi currently available. In this study, an optimized sample preparation protocol was devised for the biotyping of yeasts of oenological origin. Taking into account that commercially available reference databases comprise almost exclusively clinical microorganisms, most of them bacteria, in the present study a database of yeasts isolated from vineyards and wineries was created, and its accuracy was tested using industrial and laboratory yeast strains. In addition, the implementation of a program for MALDI-TOF MS spectra analysis has been developed as an extensible open-source platform for MALDI data processing and analysis with statistical techniques that has arisen from our previous experience working with MALDI data. The software integrates two R packages for raw MALDI data preprocessing: Continuous Wavelet Transform (CWT)-based algorithm and MassSpecWavelet. One of the advantages of the CWT is that it can be directly applied to a raw spectrum, without prior baseline correction. Mass fingerprints of 109 S. cerevisiae strains and 107 non-Saccharomyces isolates were generated by MALDI-TOF MS upon optimized sample preparation and instrument settings and analyzed for strain, species, and genus-level differentiation. As a reference method, for S. cerevisiae differentiation at strain level, the analysis of the polymorphism in the inter-delta region was chosen. The data revealed that MALDI-TOF MS can be used for the rapid and accurate identification of S. cerevisiae and non-Saccharomyces isolates at genus and species level. However, S. cerevisiae differentiation at strain level was not successfully achieved, and the differentiation among Metschnikowia species was also difficult.

      PubDate: 2017-05-17T17:54:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.003
      Issue No: Vol. 254 (2017)
       
  • Sensitive detection of viable Escherichia coli O157:H7 from foods using a
           luciferase-reporter phage phiV10lux
    • Authors: Jinwoo Kim; Minsik Kim; Seongmi Kim; Sangryeol Ryu
      Pages: 11 - 17
      Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254
      Author(s): Jinwoo Kim, Minsik Kim, Seongmi Kim, Sangryeol Ryu
      Escherichia coli O157:H7, a major foodborne pathogen, is a major public health concern associated with life-threatening diseases such as hemolytic uremic syndrome. To alleviate this burden, a sensitive and rapid system is required to detect this pathogen in various kinds of foods. Herein, we propose a phage-based pathogen detection method to replace laborious and time-consuming conventional methods. We engineered an E. coli O157:H7-specific phage phiV10 to rapidly and sensitively detect this notorious pathogen. The luxCDABE operon was introduced into the phiV10 genome and allowed the engineered phage phiV10lux to generate bioluminescence proportional to the number of viable E. coli O157:H7 cells without any substrate addition. The phage phiV10lux was able to detect at least 1CFU/ml of E. coli O157:H7 in a pure culture within 40min after 5h of pre-incubation. In artificially contaminated romaine lettuce, apple juice (pH3.51), and ground beef, the reporter phage could detect approximately 10CFU/cm2, 13CFU/ml, and 17CFU/g of E. coli O157:H7, respectively. Taken together, the constructed reporter phage phiV10lux could be applied as a powerful tool for rapid and sensitive detection of live E. coli O157:H7 in foods.

      PubDate: 2017-05-17T17:54:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.002
      Issue No: Vol. 254 (2017)
       
  • Impact of bioactive packaging systems based on EVOH films and essential
           oils in the control of aflatoxigenic fungi and aflatoxin production in
           maize
    • Authors: Eva M. Mateo; José V. Gómez; Irene Domínguez; Jose V. Gimeno-Adelantado; Rufino Mateo-Castro; Rafael Gavara; Misericordia Jiménez
      Pages: 36 - 46
      Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254
      Author(s): Eva M. Mateo, José V. Gómez, Irene Domínguez, Jose V. Gimeno-Adelantado, Rufino Mateo-Castro, Rafael Gavara, Misericordia Jiménez
      Aspergillus flavus and A. parasiticus are the most common fungal species associated with aflatoxin (AF) contamination of cereals, especially maize, and other agricultural commodities. AFB1, the most frequent and toxic metabolite, is a powerful hepatotoxic, teratogenic and mutagenic compound. Effective strategies to control these fungal species and AFs in food and feed are required. Active packaging film containing essential oils (EO) is one of the most innovative food packaging concepts. In this study, ethylene-vinyl alcohol (EVOH) copolymer films incorporating EO from Origanum vulgare (ORE), Cinnamomum zeylanicum (CIN) or their major active constituents, carvacrol (CAR) and cinnamaldehyde (CINHO), respectively, were developed and assayed to control growth of A. flavus and A. parasiticus and AF production in maize grains under different aw and temperature regimens. EO doses assayed in cultures were in the range 0.25–4.0mg/Petri dish. The factors aw, temperature, type of EVOH-EO film and fungal species significantly influenced the ED50 values of all assayed films. Growth rate (GR) of both species was usually higher at 0.99 than at 0.96 aw and at 37°C than at 25°C. However, the contrary was found with regard to AF production. The order of efficacy of EVOH-EO films to control growth of both species and AF production was EVOH-CINHO>EVOH-CAR>EVOH-ORE>EVOH-CIN. The effective dose (ED50) (mg EO/plate) for EVOH-CINHO and EVOH-CIN films against A. flavus were in the ranges of 0.125 and 2.475–3.500 and against A. parasiticus in the ranges of 0.121–0.133 and 2.275–3.625, respectively. Under the assayed conditions, the ED90 for EVOH-CINHO film were 0.22–0.23mg/plate for both species. It was the most effective bioactive film to control fungal growth (vapour phase) and AF production, regardless of aw and temperature. This is the first study about the impact that interacting environmental conditions and bioactive EVOH-CINHO, EVOH-ORE, EVOH-CIN EVOH-CAR films have on the growth of aflatoxigenic fungi and on AF production in maize grains.

      PubDate: 2017-05-17T17:54:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.007
      Issue No: Vol. 254 (2017)
       
  • Efficacy of Bacillus subtilis and Bacillus amyloliquefaciens in the
           control of Aspergillus parasiticus growth and aflatoxins production on
           pistachio
    • Authors: Fatemeh Siahmoshteh; Ilenia Siciliano; Houda Banani; Zohreh Hamidi-Esfahani; Mehdi Razzaghi-Abyaneh; Maria Lodovica Gullino; Davide Spadaro
      Pages: 47 - 53
      Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254
      Author(s): Fatemeh Siahmoshteh, Ilenia Siciliano, Houda Banani, Zohreh Hamidi-Esfahani, Mehdi Razzaghi-Abyaneh, Maria Lodovica Gullino, Davide Spadaro
      Pistachio (Pistacia vera) is an important nut for its economic, nutritional and health aspects but it can be contaminated by aflatoxigenic fungi in the field and during storage. Biological control could be considered as an alternative to chemical treatment. In this study, we evaluated the antifungal and anti-mycotoxigenic capability of two Bacillus spp. both in vitro and on pistachio kernels. In in vitro conditions, both strains were able to reduce the mycelial growth and they were able to degrade the four aflatoxins during the first three days after inoculation. AFG1 and AFG2 were rapidly degraded within two days of incubation with the bacterial strains. No aflatoxin was found in the bacterial cell walls, permitting exclusion of mycotoxin adsorption and hypothesis of an in vitro biodegradation as a mode of action. The cultivar of pistachio most susceptible to fungal colonization was ‘Ahmad-Aghaei’, selected among four main Iranian cultivars. A. parasiticus was able to grow and produce aflatoxins on pistachios, but at longer inoculation periods, a natural decrease of aflatoxins was registered. Both strains were able to reduce the fungal incidence and number of spores on pistachio with a stronger effect during the first 5dpi. The effect on aflatoxin content in vivo was less pronounced than in vitro, with a maximum effect at 8dpi. At longer times, there was a contrasting effect due to the lower activity of Bacillus spp. in stationary phase and higher growth of Aspergillus species. This consideration could explain the lack of aflatoxin reduction at 12dpi. Both bacterial strains showed good antifungal activity and aflatoxin reduction in in vitro conditions and on pistachio kernels. Altogether, these results indicate that Bacillus species could be considered as potential biocontrol agents to combat toxigenic fungal growth and subsequent aflatoxin contamination of nuts and agricultural crops in practice.

      PubDate: 2017-05-22T18:00:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.011
      Issue No: Vol. 254 (2017)
       
  • Evaluation of radio-frequency heating in controlling Salmonella enterica
           in raw shelled almonds
    • Authors: Seul-Gi Jeong; Oon-Doo Baik; Dong-Hyun Kang
      Pages: 54 - 61
      Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254
      Author(s): Seul-Gi Jeong, Oon-Doo Baik, Dong-Hyun Kang
      This study was conducted to investigate the efficacy of radio-frequency (RF) heating to reduce Salmonella enterica serovars Enteritidis, Typhimurium, and Senftenberg in raw shelled almonds compared to conventional convective heating, and the effect of RF heating on quality by measuring changes in the color and degree of lipid oxidation. Agar-grown cells of three pathogens were inoculated onto the surface or inside of raw shelled almonds using surface inoculation or the vacuum perfusion method, respectively, and subjected to RF or conventional heating. RF heating for 40s achieved 3.7-, 6.0-, and 5.6-log reductions in surface-inoculated S. Enteritidis, S. Typhimurium, and S. Senftenberg, respectively, whereas the reduction of these pathogens following convective heating for 600s was 1.7, 2.5, and 3.7 log, respectively. RF heating reduced internally inoculated pathogens to below the detection limit (0.7 logCFU/g) after 30s. However, conventional convective heating did not attain comparable reductions even at the end of treatment (600s). Color values, peroxide values, and acid values of RF-treated (40-s treatment) almonds were not significantly (P >0.05) different from those of nontreated samples. These results suggest that RF heating can be applied to control internalized pathogens as well as surface-adhering pathogens in raw almonds without affecting product quality.

      PubDate: 2017-05-27T18:06:01Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.007
      Issue No: Vol. 254 (2017)
       
  • Investigating the biocontrol and anti-biofilm potential of a three phage
           cocktail against Cronobacter sakazakii in different brands of infant
           formula
    • Authors: Lorraine Endersen; Colin Buttimer; Eoghan Nevin; Aidan Coffey; Horst Neve; Hugo Oliveira; Rob Lavigne; Jim O'Mahony
      Pages: 1 - 11
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): Lorraine Endersen, Colin Buttimer, Eoghan Nevin, Aidan Coffey, Horst Neve, Hugo Oliveira, Rob Lavigne, Jim O'Mahony
      In recent years, the microbiological safety of powdered infant formula has gained increasing attention due to the identification of contaminating C. sakazakii and its epidemiological link with life-threatening neonatal infections. Current intervention strategies have fallen short of ensuring the production of infant formula that is free from C. sakazakii. In this study, we describe the isolation and characterisation of three bacteriophages (phages) and their application as a phage cocktail to inhibit the growth of C. sakazakii in different brands of infant formula, while also assessing the phages ability to prevent biofilm formation. All three phages, isolated from slurry, possess a relatively broad host range, verified by their ability to infect across genera and species. When all three phages were combined and used as part of a phage cocktail, 73% coverage was obtained across all Cronobacter strains tested. Optimum thermo-tolerance and pH stability were determined between 4°C–37°C, and pH6–8, respectively, well within the normal range of application of infant formula. Genome sequencing and analysis revealed all the phages to be free from lysogenic properties, a trait which renders each favourable for phage therapy applications. As such, the combined-phage preparation (3×108 pfu/mL) was found to possess a strong bactericidal effect on C. sakazakii/C. sakazakii LUX cells (≤104 cfu/mL), resulting in a significant reduction in cell numbers, to below the limit of detection (<10cfu/mL). This was observed following a 20h challenge in different brands of infant formula, where samples in the absence of the phage cocktail reached concentrations of ~109 cfu/mL. The phage cocktail also demonstrated promise in preventing the establishment of biofilm, as biofilm formation could not be detected for up to 48h post treatment. These results highlight the potential application of this phage preparation for biocontrol of C. sakazakii contamination in reconstituted infant formula and also as a preventative agent against biofilm formation.

      PubDate: 2017-05-02T16:52:38Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.009
      Issue No: Vol. 253 (2017)
       
  • Effects of meat juice on biofilm formation of Campylobacter and Salmonella
    • Authors: Jiaqi Li; Jinsong Feng; Lina Ma; César de la Fuente Núñez; Greta Gölz; Xiaonan Lu
      Pages: 20 - 28
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): Jiaqi Li, Jinsong Feng, Lina Ma, César de la Fuente Núñez, Greta Gölz, Xiaonan Lu
      Campylobacter and Salmonella are leading causes of foodborne illnesses worldwide, vastly harboured by raw meat as their common food reservoir. Both microbes are prevalent in meat processing environments in the form of biofilms that contribute to cross-contamination and foodborne infection. This study applied raw meat juice (chicken juice and pork juice) as a minimally processed food model to study its effects on bacterial biofilm formation. Meat juice was collected during the freeze-thaw process of raw meat and sterilized by filtration. In 96-well polystyrene plates and glass chambers, supplementation of over 25% meat juice (v/v) in laboratory media led to an increase in biofilm formation of Campylobacter and Salmonella. During the initial attachment stage of biofilm development, more bacterial cells were present on surfaces treated with meat juice residues compared to control surfaces. Meat juice particulates on abiotic surfaces facilitated biofilm formation of Campylobacter and Salmonella under both static and flow conditions, with the latter being assessed using a microfluidic platform. Further, the deficiency in biofilm formation of selected Campylobacter and Salmonella mutant strains was restored in the presence of meat juice particulates. These results suggested that meat juice residues on the abiotic surfaces might act as a surface conditioner to support initial attachment and biofilm formation of Campylobacter and Salmonella. This study sheds light on a possible survival mechanism of Campylobacter and Salmonella in meat processing environments, and indicates that thorough cleaning of meat residues during meat production and handling is critical to reduce the bacterial load of Campylobacter and Salmonella.

      PubDate: 2017-05-08T16:55:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.013
      Issue No: Vol. 253 (2017)
       
  • Headspace oxygen as a hurdle to improve the safety of in-pack pasteurized
           chilled food during storage at different temperatures
    • Authors: Nydia Muñoz; Kanishka Bhunia; Hongchao Zhang; Gustavo V. Barbosa-Cánovas; Juming Tang; Shyam Sablani
      Pages: 29 - 35
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): Nydia Muñoz, Kanishka Bhunia, Hongchao Zhang, Gustavo V. Barbosa-Cánovas, Juming Tang, Shyam Sablani
      This study investigated the use of headspace oxygen in a model food system to prevent the growth of anaerobic pathogenic bacteria in in-pack pasteurized food at various storage temperatures. Three model food formulations prepared with tryptic soy broth and three agar concentrations (0.1, 0.4 and 1.0%) were sealed without removing the air from the package in high oxygen barrier pouches (OTR=0.3cm3/m2·day·atm). Important properties influencing bacterial growth, including pH and water activity (aw) were determined. The oxygen sorption kinetics of each model food were obtained at three different storage temperatures (8, 12, and 20°C) using an OxySense Gen III 300 system. An analytical solution of Fick's second law was used to determine the O2 diffusion coefficient. Growth challenge studies at 12 and 20°C were conducted at three selected locations (top, center and bottom layers) in model foods containing 1% agar. Model foods were inoculated with Clostridium sporogenes PA 3679 (300spores/mL), and were classified as low-acid (pH>4.5, aw >0.85). When the storage temperature decreased from 20 to 8°C, the oxygen diffusion decreased from 0.82×10−9 m2/s to 0.68×10−9 m2/s. As the agar concentration was increased from 0.1 to 1.0%, the effective oxygen permeability decreased significantly (p =0.007) from 0.88×10−9 m2/s to 0.65×10−9 m2/s. When the inoculated model foods were stored at 12°C for 14days, C. sporogenes PA 3679 was unable to grow. As the storage temperature was increased to 20°C, significant bacterial growth was observed with storage time (p <0.0001), and the C. sporogenes PA 3679 population increased by around 6logCFU/g. However, the location of the food did not influence the growth distribution of C. sporogenes PA 3679. These results demonstrate that oxygen diffusion from the pouch headspace was primarily limited to the food surface. Findings suggest that the air/oxygen present in the package headspace may not be considered as a food safety hurdle in the production of pasteurized packaged food.

      PubDate: 2017-05-08T16:55:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.018
      Issue No: Vol. 253 (2017)
       
  • A novel typing method for Listeria monocytogenes using high-resolution
           melting analysis (HRMA) of tandem repeat regions
    • Authors: Chihiro Ohshima; Hajime Takahashi; Ai Iwakawa; Takashi Kuda; Bon Kimura
      Pages: 36 - 42
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): Chihiro Ohshima, Hajime Takahashi, Ai Iwakawa, Takashi Kuda, Bon Kimura
      Listeria monocytogenes, which is responsible for causing food poisoning known as listeriosis, infects humans and animals. Widely distributed in the environment, this bacterium is known to contaminate food products after being transmitted to factories via raw materials. To minimize the contamination of products by food pathogens, it is critical to identify and eliminate factory entry routes and pathways for the causative bacteria. High resolution melting analysis (HRMA) is a method that takes advantage of differences in DNA sequences and PCR product lengths that are reflected by the disassociation temperature. Through our research, we have developed a multiple locus variable-number tandem repeat analysis (MLVA) using HRMA as a simple and rapid method to differentiate L. monocytogenes isolates. While evaluating our developed method, the ability of MLVA-HRMA, MLVA using capillary electrophoresis, and multilocus sequence typing (MLST) was compared for their ability to discriminate between strains. The MLVA-HRMA method displayed greater discriminatory ability than MLST and MLVA using capillary electrophoresis, suggesting that the variation in the number of repeat units, along with mutations within the DNA sequence, was accurately reflected by the melting curve of HRMA. Rather than relying on DNA sequence analysis or high-resolution electrophoresis, the MLVA-HRMA method employs the same process as PCR until the analysis step, suggesting a combination of speed and simplicity. The result of MLVA-HRMA method is able to be shared between different laboratories. There are high expectations that this method will be adopted for regular inspections at food processing facilities in the near future.

      PubDate: 2017-05-08T16:55:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.015
      Issue No: Vol. 253 (2017)
       
  • Epidemiology of antimicrobial resistant Campylobacter spp. isolated from
           retail meats in Canada
    • Authors: Claudia Narvaez-Bravo; Eduardo N. Taboada; Steven K. Mutschall; Mueen Aslam
      Pages: 43 - 47
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): Claudia Narvaez-Bravo, Eduardo N. Taboada, Steven K. Mutschall, Mueen Aslam
      Campylobacter is an important zoonotic pathogen found in livestock and can cause illness in humans following consumption of raw and undercooked meat products. The objectives of this study were to determine the prevalence of Campylobacter spp. in retail meat (poultry, turkey, pork and beef) purchased in Alberta, Canada and to assess antimicrobial resistance and genetic relatedness of recovered Campylobacter strains with previously isolated strains from clinical and environmental sources. A Comparative Genomic Fingerprinting (CGF) method was used for assessing genetic relatedness of isolates. A total of 606 samples comprising 204, 110, 145 and 147 samples of retail chicken, turkey, ground beef and pork, respectively, were obtained. Campylobacter was isolated from 23.5% (48/204) of chicken samples and 14.2% (8/110) of turkey samples. Pork and beef samples were negative for Campylobacter. Campylobacter jejuni was the most common (94.6%) spp. found followed by C. coli (5.4%). Resistance to tetracycline was found in 48.1% of isolates, followed by resistance to ciprofloxacin (5.5%), nalidixic acid (5.5%), azithromycin (1.78%), and erythromycin (1.78%). All isolates were susceptible to clindamycin, florfenicol, gentamicin and telithromycin. Tetracycline resistance was attributable to the presence of the tetO gene. CGF analysis showed that Campylobacter isolated from poultry meat in this study were genetically related to clinical isolates recovered from human infections and to those isolated from animals and the environment.

      PubDate: 2017-05-08T16:55:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.019
      Issue No: Vol. 253 (2017)
       
  • Two complementary approaches to quantify variability in heat resistance of
           spores of Bacillus subtilis
    • Authors: Heidy M.W. den Besten; Erwin M. Berendsen; Marjon H.J. Wells-Bennik; Han Straatsma; Marcel H. Zwietering
      Pages: 48 - 53
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): Heidy M.W. den Besten, Erwin M. Berendsen, Marjon H.J. Wells-Bennik, Han Straatsma, Marcel H. Zwietering
      Realistic prediction of microbial inactivation in food requires quantitative information on variability introduced by the microorganisms. Bacillus subtilis forms heat resistant spores and in this study the impact of strain variability on spore heat resistance was quantified using 20 strains. In addition, experimental variability was quantified by using technical replicates per heat treatment experiment, and reproduction variability was quantified by using two biologically independent spore crops for each strain that were heat treated on different days. The fourth-decimal reduction times and z-values were estimated by a one-step and two-step model fitting procedure. Grouping of the 20 B. subtilis strains into two statistically distinguishable groups could be confirmed based on their spore heat resistance. The reproduction variability was higher than experimental variability, but both variabilities were much lower than strain variability. The model fitting approach did not significantly affect the quantification of variability. Remarkably, when strain variability in spore heat resistance was quantified using only the strains producing low-level heat resistant spores, then this strain variability was comparable with the previously reported strain variability in heat resistance of vegetative cells of Listeria monocytogenes, although in a totally other temperature range. Strains that produced spores with high-level heat resistance showed similar temperature range for growth as strains that produced low-level heat resistance. Strain variability affected heat resistance of spores most, and therefore integration of this variability factor in modelling of spore heat resistance will make predictions more realistic.

      PubDate: 2017-05-08T16:55:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.014
      Issue No: Vol. 253 (2017)
       
  • Effects of ambient exposure, refrigeration, and icing on Vibrio vulnificus
           and Vibrio parahaemolyticus abundances in oysters
    • Authors: J.L. Jones; K.A. Lydon; T.P. Kinsey; B. Friedman; M. Curtis; R. Schuster; J.C. Bowers
      Pages: 54 - 58
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): J.L. Jones, K.A. Lydon, T.P. Kinsey, B. Friedman, M. Curtis, R. Schuster, J.C. Bowers
      Vibrio vulnificus (Vv) and V. parahaemolyticus (Vp) illnesses are typically acquired through the consumption of raw molluscan shellfish, particularly oysters. As Vibrio spp. are naturally-occurring bacteria, one means of mitigation of illness is achieved by limiting post-harvest growth. In this study, effects of ambient air storage, refrigeration, and icing of oysters on Vibrio spp. abundances were examined at two sites in Alabama (AL) [Dog River (DR) and Cedar Point (CP)] and one site in Delaware Bay, New Jersey (NJ). As the United States shellfish program recommendations include testing for total these organisms and gene targets, Vv and total (tlh) and pathogenic (tdh+ and trh+) Vp were enumerated from samples using MPN-real-time-PCR approaches. Mean Vv and Vp abundances in oysters from AL-DR were lowest in immediately iced samples (2.3 and −0.1 log MPN/g, respectively) and highest in the 5h ambient then refrigerated samples (3.4 and 0.5 log MPN/g, respectively). Similarly, in AL-CP Vv and Vp mean levels in oysters were lowest in immediately iced samples (3.6 and 1.2 log MPN/g, respectively) and highest in 5h ambient then refrigerated samples (5.1 and 3.2 log MPN/g, respectively). Mean levels of pathogenic Vp from AL sites were frequently below the limit of detection (<0.3 MPN/g). In NJ, Vv and Vp mean abundances in oysters were highest in samples which were held for 7h in the shade (5.3 and 4.8 log MPN/g, respectively). Mean pathogenic Vp levels in oysters at initial harvest were also highest in oysters 7h in the shade (2.1 and 2.2 log MPN/g for tdh+ and trh+ Vp). Regardless of sampling location, Vibrio spp. levels were generally significantly (p<0.05) greater in oysters exposed to 5h of air storage compared to the initially harvested samples. In addition, the data demonstrated that the use of layered ice resulted in lower Vibrio spp. levels in oysters, compared to those that were refrigerated post-harvest. These results suggest vibriosis risk can be mitigated by shorter storage times and more rapid cooling of oysters, providing data regulatory authorities can use to evaluate Vibrio spp. control plans.

      PubDate: 2017-05-08T16:55:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.016
      Issue No: Vol. 253 (2017)
       
  • Molecular characterization of O157:H7, O26:H11 and O103:H2 Shiga
           toxin-producing Escherichia coli isolated from dairy products
    • Authors: T. Douëllou; S. Delannoy; S. Ganet; P. Fach; E. Loukiadis; M.-C. Montel; D. Sergentet-Thevenot
      Pages: 59 - 65
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): T. Douëllou, S. Delannoy, S. Ganet, P. Fach, E. Loukiadis, M.-C. Montel, D. Sergentet-Thevenot
      Pathogenic Shiga toxin-producing E. coli (STEC) are recognized worldwide as environment and foodborne pathogens which can be transmitted by ingestion of ready-to-eat food such as raw milk-derived products. STEC show a prevalence rate in dairy products of 0.9%, yet comparably few outbreaks have been related to dairy products consumption. In this study, we used rt-qPCR to identify the virulence potential of O157, O26 and O103 STEC strains isolated from raw-milk dairy products by analyzing virulence-related gene frequencies and associations with O-island (OI) 44, OI-48, OI-50, OI-57, OI-71 and OI-122. Results showed that 100% of STEC strains investigated harbored genes associated with EHEC-related virulence profile patterns (eae and stx, with either espK, espV, ureD and/or Z2098). We also found similarities in virulence-related gene content between O157:H7 and O103:H2 dairy and non-dairy STEC strains, especially isolates from human cases. The O26:H11-serotype STEC strains investigated harbor the arcA-allele 2 gene associated with specific genetic markers. These profiles are associated with high-virulence seropathotype-A STEC. However, the low frequency of stx2 gene associated with absence of other virulence genes in dairy isolates of O26:H11 remains a promising avenue of investigation to estimate their real pathogenicity. All O26:H11 attaching-effacing E. coli (AEEC) strains carried CRISPRO26:H11 SP_O26_E but not genetic markers espK, espV, ureD and/or Z2098 associated with the emerging potentially high-virulence “new French clone”. These strains are potentially as “EHEC-like” strains because they may acquire (or have lost) stx gene. In this study, O157:H7, O103:H2 and O26:H11 STEC strains isolated from dairy products were assigned as potential pathogens. However, research now needs to investigate the impact of dairy product environment and dairy processing on the expression of their pathogenicity.

      PubDate: 2017-05-13T09:09:56Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.010
      Issue No: Vol. 253 (2017)
       
  • Development of a gold nanoparticle-based universal oligonucleotide
           microarray for multiplex and low-cost detection of foodborne pathogens
    • Authors: Xiaoqiang Wang; Sisi Ying; Xiaoguang Wei; Jun Yuan
      Pages: 66 - 74
      Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253
      Author(s): Xiaoqiang Wang, Sisi Ying, Xiaoguang Wei, Jun Yuan
      Bacterial foodborne diseases remain major threats to food safety and public health, especially in developing countries. In this study a novel assay, combining gold nanoparticle (GNP)-based multiplex oligonucleotide ligation-PCR and universal oligonucleotide microarray technology, was developed for inexpensive, specific, sensitive, and multiplex detection of eight common foodborne pathogens, including Shigella spp., Campylobacter jejuni, Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, and Vibrio parahaemolyticus. The target fragments of the eight pathogens were enriched by multiplex PCR and subjected to multiplex ligase detection reaction. Ligation products were enriched and labeled with GNPs by universal asymmetric PCR, using excess GNP-conjugated primers. The labeled single-stranded amplicons containing complementary tag sequences were captured by the corresponding tag sequences immobilized on microarrays, followed by silver staining for signal enhancement. Black images of microarray spots were visualized by naked eyes or scanned on a simple flatbed scanner, and quantified. The results indicated that this assay could unambiguously discriminate all eight pathogens in single and multiple infections, with detection sensitivity of 3.3–85CFU/mL for pure cultures. Microarray results of ninety-five artificially contaminated and retail food samples were consistent with traditional culture, biochemical and real-time PCR findings. Therefore, the novel assay has the potential to be used for routine detection due to rapidity, low cost, and high specificity and sensitivity.

      PubDate: 2017-05-13T09:09:56Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.005
      Issue No: Vol. 253 (2017)
       
  • 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
       
  • Inside Front Cover - Editorial Board
    • Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256


      PubDate: 2017-06-12T12:33:19Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 1 September 2017
      Source:International Journal of Food Microbiology, Volume 256


      PubDate: 2017-06-12T12:33:19Z
       
  • Inside Front Cover - Editorial Board
    • Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255


      PubDate: 2017-06-12T12:33:19Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 16 August 2017
      Source:International Journal of Food Microbiology, Volume 255


      PubDate: 2017-06-12T12:33:19Z
       
  • Inside Front Cover - Editorial Board
    • Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254


      PubDate: 2017-06-12T12:33:19Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254


      PubDate: 2017-06-12T12:33:19Z
       
  • Inside Front Cover - Editorial Board
    • Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253


      PubDate: 2017-05-27T18:06:01Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 17 July 2017
      Source:International Journal of Food Microbiology, Volume 253


      PubDate: 2017-05-27T18:06:01Z
       
  • Spray-dried adjunct cultures of autochthonous non-starter lactic acid
           bacteria
    • Authors: Guillermo H. Peralta; Carina V. Bergamini; Gabriela Audero; Roxana Páez; I. Veronica Wolf; M. Cristina Perotti; Erica R. Hynes
      Abstract: Publication date: Available online 22 May 2017
      Source:International Journal of Food Microbiology
      Author(s): Guillermo H. Peralta, Carina V. Bergamini, Gabriela Audero, Roxana Páez, I. Veronica Wolf, M. Cristina Perotti, Erica R. Hynes
      Spray-drying of lactic cultures provides direct-to-vat starters, which facilitate their commercialization and use. However, this process may alter the metabolic activity and deteriorate technological features. In this work, we assessed the influence of spray-drying on the survival and aroma production of two strains of mesophilic lactobacilli: Lactobacillus paracasei 90 and Lactobacillus plantarum 91, which have already been characterized as good adjunct cultures. The spray-drying was carried out using a laboratory scale spray and the dried cultures were monitored during the storage for the survival rate. The dried cultures were applied to two cheese models: sterile cheese extract and miniature soft cheese. The influence on the carbohydrate metabolism and the production of organic acids and volatile compounds was determined. Both strains retained high levels of viable counts in the powder after drying and during the storage at 5°C for twelve months. In addition, they also remained at high level in both cheese models during incubation or ripening. Similar profiles of carbohydrate fermentation and bioformation of volatile compounds were observed in the cheese extracts for each of the strains when tested as both fresh and dried cultures. In addition, the ability of Lb. paracasei 90 to increase the production of acetoin and diacetyl remarkably in cheese models was also confirmed for the spray-dried culture.

      PubDate: 2017-05-22T18:00:24Z
      DOI: 10.1016/j.ijfoodmicro.2017.05.014
       
  • Adaptive conditions and safety of the application of Penicillium
           frequentans as a biocontrol agent on stone fruit
    • Authors: Guijarro Inmaculada; Larena Paloma Melgarejo Antonieta Cal
      Abstract: Publication date: 2 August 2017
      Source:International Journal of Food Microbiology, Volume 254
      Author(s): Belén Guijarro, Inmaculada Larena, Paloma Melgarejo, Antonieta De Cal
      Penicillium frequentans (Pf909) reduces brown rot caused by Monilinia spp. in stone fruit. The registration of a microbial biocontrol agent in Europe requires information on the risks and safety of a biological product. This study focused on the impact of the physical environment on Pf909 survival and growth, Pf909 mycotoxin production on fruit surface, and the Pf909 resistance to commercial antifungal compounds used in animal and human medicine. The effect of temperature (4 to 37°C), water activity (0.999 to 0.900), pH (3 to 11), light intensity (0, 90 and 180lm) and photoperiod (0/24, 12/12, 16/8, 24/0; light/dark) on mycelial growth and sporulation of Pf909 were monitored for 10days in vitro on culture medium. Antifungal activity of antifungal compounds on mycelial growth of Pf909 was also measured by a quantitative micro spectrophotometric assay after 72h of incubation. The presence or absence of four non-volatile mycotoxins (patulin, penicillic acid, ochratoxin A and citrinin) on nectarine surfaces treated with Pf909 was determined by HPLC. Growth rate was significantly influenced by water activity, temperature and light exposure conditions. Pf909 showed maximum growth and sporulation at 22°C and 25°C, in wet conditions (0.999 water activity), with a pH5.6 to 9, and in darkness or a short light photoperiod. Our results showed all antifungal compounds used reduced significantly Pf909 mycelial growth at tested commercial doses. HPLC data analysis showed that 7days after biofungicide (Pf909) application there were no mycotoxin products on the surface of nectarine. Finally, no phylogenetic relationship has been shown among Pf909 and other species of Penicillium that produce mycotoxins. In conclusion, from an ecological point of view, Pf909 would establish and survive actively over a broad range of climatic conditions. The probability of risks to human and animal health is considered very low.

      PubDate: 2017-05-17T17:54:16Z
       
  • Inside Front Cover - Editorial Board
    • Abstract: Publication date: 3 July 2017
      Source:International Journal of Food Microbiology, Volume 252


      PubDate: 2017-05-17T17:54:16Z
       
  • Abiotic conditions leading to FUM gene expression and fumonisin
           accumulation by Fusarium proliferatum strains grown on a wheat-based
           substrate
    • Authors: Eugenia Cendoya; Laetitia Pinson-Gadais; María C. Farnochi; María L. Ramirez; Sylvain Chéreau; Giselè Marcheguay; Christine Ducos; Christian Barreau; Florence Richard-Forget
      Abstract: Publication date: Available online 25 April 2017
      Source:International Journal of Food Microbiology
      Author(s): Eugenia Cendoya, Laetitia Pinson-Gadais, María C. Farnochi, María L. Ramirez, Sylvain Chéreau, Giselè Marcheguay, Christine Ducos, Christian Barreau, Florence Richard-Forget
      Fusarium proliferatum produces fumonisins B not only on maize but also on diverse crops including wheat. Using a wheat-based medium, the effects of abiotic factors, temperature and water activity (aW), on growth, fumonisin biosynthesis, and expression of FUM genes were compared for three F. proliferatum strains isolated from durum wheat in Argentina. Although all isolates showed similar profiles of growth, the fumonisin production profiles were slightly different. Regarding FUM gene transcriptional control, both FUM8 and FUM19 expression showed similar behavior in all tested conditions. For both genes, expression at 25°C correlated with fumonisin production, irrespective of the aw conditions. However, at 15°C, these two genes were as highly expressed as at 25°C although the amounts of toxin were very weak, suggesting that the kinetics of fumonisin production was slowed at 15°C. This study provides useful baseline data on conditions representing a low or a high risk for contamination of wheat kernels with fumonisins.

      PubDate: 2017-04-26T16:47:26Z
      DOI: 10.1016/j.ijfoodmicro.2017.04.017
       
 
 
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