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MICROBIOLOGY (262 journals)                  1 2 | Last

Showing 1 - 200 of 262 Journals sorted alphabetically
Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Neurobiologiae Experimentalis     Open Access  
Addiction Genetics     Open Access   (Followers: 8)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22)
Advances in Microbiology     Open Access   (Followers: 24)
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 Current Microbiology     Open Access  
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 24)
American Journal of Microbiological Research     Open Access   (Followers: 2)
American Journal of Molecular Biology     Open Access   (Followers: 2)
American Journal of Stem Cell Research     Open Access   (Followers: 5)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 9)
Annals of Microbiology     Hybrid Journal   (Followers: 10)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 41)
Antimicrobial Agents and Chemotherapy     Hybrid Journal   (Followers: 25)
Antiviral Research     Hybrid Journal   (Followers: 8)
Applied and Environmental Microbiology     Hybrid Journal   (Followers: 46)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 16)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 63)
Aquatic Microbial Ecology     Hybrid Journal   (Followers: 5)
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: 3)
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
Bio-Research     Full-text available via subscription   (Followers: 2)
BioArchitecture     Full-text available via subscription  
Bioethanol     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 10)
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: 12)
Brazilian Journal of Microbiology     Open Access   (Followers: 3)
Canadian Journal of Infectious Diseases and Medical Microbiology     Open Access   (Followers: 5)
Canadian Journal of Microbiology     Hybrid Journal   (Followers: 6)
Cell Biology : Research & Therapy     Hybrid Journal   (Followers: 5)
Cell Biology and Development     Open Access  
Cell Host & Microbe     Full-text available via subscription   (Followers: 21)
Cell Medicine     Open Access   (Followers: 5)
Cell Regeneration     Open Access   (Followers: 1)
Cell Stem Cell     Full-text available via subscription   (Followers: 36)
CellBio     Open Access  
Cells     Open Access   (Followers: 2)
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 13)
Cellular and Molecular Biology Letters     Open Access   (Followers: 1)
Cellular and Molecular Life Sciences (CMLS)     Hybrid Journal   (Followers: 5)
Cellular Microbiology     Hybrid Journal   (Followers: 9)
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (Followers: 2)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (Followers: 22)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 8)
Clinical Microbiology Reviews     Hybrid Journal   (Followers: 15)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 12)
Computational Molecular Bioscience     Open Access   (Followers: 2)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 14)
Current Clinical Microbiology Reports     Hybrid Journal   (Followers: 3)
Current Issues in Molecular Biology     Open Access   (Followers: 3)
Current Microbiology     Hybrid Journal   (Followers: 15)
Current Molecular Biology Reports     Hybrid Journal   (Followers: 1)
Current Opinion in Microbiology     Hybrid Journal   (Followers: 34)
Current Regenerative Medicine     Hybrid Journal  
Current Research in Microbiology     Open Access   (Followers: 18)
Current Tissue Engineering     Hybrid Journal   (Followers: 3)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 12)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 9)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (Followers: 4)
Environmental Microbiology     Hybrid Journal   (Followers: 22)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 7)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 13)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 5)
Epigenomes     Open Access  
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 19)
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: 10)
Fems Microbiology Letters     Hybrid Journal   (Followers: 22)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 27)
Fermentation     Open Access   (Followers: 1)
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 18)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 5)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 3)
Frontiers in Cellular Neuroscience     Open Access   (Followers: 8)
Frontiers in Microbiology     Open Access   (Followers: 15)
Frontiers in Molecular Neuroscience     Open Access   (Followers: 5)
Future Microbiology     Hybrid Journal   (Followers: 5)
Future Virology     Hybrid Journal   (Followers: 9)
Gene Expression     Full-text available via subscription   (Followers: 1)
Genetics and Molecular Research     Open Access   (Followers: 4)
Geomicrobiology Journal     Hybrid Journal   (Followers: 3)
Gut Microbes     Full-text available via subscription   (Followers: 9)
IAWA Journal     Hybrid Journal   (Followers: 1)
Indian Journal of Microbiology     Hybrid Journal   (Followers: 2)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 2)
Infection Ecology & Epidemiology     Open Access   (Followers: 5)
Inside the Cell     Open Access  
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 10)
International Journal of Bioassays     Open Access   (Followers: 1)
International Journal of Biotechnology and Molecular Biology Research     Open Access   (Followers: 2)
International Journal of Food Microbiology     Hybrid Journal   (Followers: 13)
International Journal of Genetics and Molecular Biology     Open Access  
International Journal of Infection and Microbiology     Open Access   (Followers: 2)
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: 1)
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: 16)
Journal of Bacteriology     Hybrid Journal   (Followers: 27)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 2)
Journal of Biochemistry and Molecular Biology Research     Open Access  
Journal of Biomolecular Structure and Dynamics     Hybrid Journal   (Followers: 2)
Journal of Bionanoscience     Full-text available via subscription  
Journal of Bone Marrow Research     Open Access   (Followers: 2)
Journal of Brewing and Distilling     Open Access   (Followers: 2)
Journal of Cell and Animal Biology     Open Access  
Journal of Cell Biology and Genetics     Open Access   (Followers: 2)
Journal of Clinical Microbiology     Hybrid Journal   (Followers: 31)
Journal of Clinical Pathology     Full-text available via subscription   (Followers: 10)
Journal of Extracellular Vesicles     Open Access   (Followers: 4)
Journal of Food Microbiology     Open Access   (Followers: 5)
Journal of General and Molecular Virology     Open Access   (Followers: 1)
Journal of Genes and Cells     Open Access   (Followers: 1)
Journal of Global Antimicrobial Resistance     Hybrid Journal   (Followers: 2)
Journal of Industrial Microbiology and Biotechnology     Hybrid Journal   (Followers: 16)
Journal of Medical Microbiology     Full-text available via subscription   (Followers: 5)
Journal of Microbiological Methods     Hybrid Journal   (Followers: 3)
Journal of Microbiology     Hybrid Journal   (Followers: 8)
Journal of Microbiology and Antimicrobials     Open Access   (Followers: 2)
Journal of Microbiology Research     Open Access   (Followers: 7)
Journal of Micropalaeontology     Hybrid Journal   (Followers: 3)
Journal of Molecular Biochemistry     Open Access   (Followers: 4)
Journal of Molecular Biology Research     Open Access   (Followers: 3)
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 11)
Journal of Molecular Psychiatry     Open Access   (Followers: 9)
Journal of Morphology     Hybrid Journal   (Followers: 6)
Journal of Organic and Biomolecular Simulations     Open Access  
Journal of Pharmacy & Bioresources     Full-text available via subscription   (Followers: 3)
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   (Followers: 1)
Medical Mycology     Open Access   (Followers: 4)
Memórias do Instituto Oswaldo Cruz     Open Access  
Metagenomics     Unknown  
Methods in Molecular Biology     Hybrid Journal   (Followers: 19)
Microbes and Health     Open Access   (Followers: 1)
Microbes and Infection     Full-text available via subscription   (Followers: 6)
Microbial Biotechnology     Open Access   (Followers: 9)
Microbial Cell Factories     Open Access   (Followers: 8)
Microbial Drug Resistance     Hybrid Journal   (Followers: 4)
Microbial Ecology     Hybrid Journal   (Followers: 11)
Microbial Ecology in Health and Disease     Open Access   (Followers: 1)
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: 15)
Microbiology (SGM)     Full-text available via subscription   (Followers: 19)
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: 2)
Microbiology Indonesia     Open Access  
Microbiology Research     Open Access   (Followers: 7)
MicrobiologyOpen     Open Access   (Followers: 2)
Microbiome     Hybrid Journal   (Followers: 10)
Microbiome Science and Medicine     Open Access   (Followers: 3)
Microorganisms     Open Access   (Followers: 2)
MicroRNA     Hybrid Journal   (Followers: 1)
Molecular and Cellular Therapies     Open Access  
Molecular Biology and Genetic Engineering     Open Access   (Followers: 2)
Molecular Biology Research Communications     Open Access   (Followers: 1)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 3)
Molecular Genetics, Microbiology and Virology     Hybrid Journal   (Followers: 6)
Molecular Imaging     Open Access  
Molecular Imaging and Biology     Hybrid Journal   (Followers: 1)
Molecular Medicine     Open Access   (Followers: 3)

        1 2 | Last

Journal Cover International Journal of Food Microbiology
  [SJR: 1.64]   [H-I: 142]   [13 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0168-1605
   Published by Elsevier Homepage  [3175 journals]
  • Yersinia enterocolitica in a Brazilian pork production chain: Tracking of
           contamination routes, virulence and antimicrobial resistance
    • Abstract: Publication date: 2 July 2018
      Source:International Journal of Food Microbiology, Volume 276
      Author(s): Bruna Torres Furtado Martins, Clarisse Vieira Botelho, Danilo Augusto Lopes Silva, Frederico Germano Piscitelli Alvarenga Lanna, Juliana Libero Grossi, Maria Emilene Martino Campos-Galvão, Ricardo Seiti Yamatogi, Juliana Pfrimer Falcão, Luciano dos Santos Bersot, Luís Augusto Nero
      This study aimed to track Yersinia enterocolitica contamination in a pork production chain in Minas Gerais, Brazil, and to characterize the virulence and antibiotic resistance of isolates. Samples were collected from four different steps of the pork production chain (pig farm, carcass, processing environment and end product; n = 870), and tested for the presence of Y. enterocolitica. The pathogen was detected in 8 samples (palatine tonsils = 5; mesenteric lymph nodes = 2; carcass after bleeding = 1), from which 16 isolates were obtained and identified as Y. enterocolitica bioserotype 4/O:3. XbaI macrorestriction allowed the clustering of isolates in 5 pulsetypes, and the identification of identical profiles of Y. enterocolitca isolated from different samples. All isolates were positive for the virulence related genes ail, virF, myfA, ystA, tccC, ymoA, hreP and sat, and negative for ystB, ystC, fepA, fepD and fes. Considering 17 antibiotics from 11 classes, only ciprofloxacin and kanamycin were effective against all isolates, and three multidrug resistance profiles were identified among them, with simultaneous resistance to 9 of 11 classes. All isolates presented positive results for emrD, yfhD and marC, related to multidrug resistance. The results of this study demonstrated the contamination routes of Y. enterocolitica within the assessed pork production chain, and highlighted the pathogenic potential and antibiotic resistance of this foodborne pathogen.

      PubDate: 2018-04-15T21:52:55Z
  • Electrolyzed water and mild-thermal processing of Atlantic salmon (Salmo
           salar): Reduction of Listeria monocytogenes and changes in protein
    • Abstract: Publication date: 2 July 2018
      Source:International Journal of Food Microbiology, Volume 276
      Author(s): Mahmoudreza Ovissipour, Setareh Ghorban Shiroodi, Barbara Rasco, Juming Tang, Shyam S. Sablani
      This study investigated the effect of different electrolyzed water (EO) solutions, including acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW), alone and in combination with mild thermal processing (50, 55, 60, 65 °C) at different exposure times (2, 6, 10 min) on the reduction of Listeria monocytogenes on Atlantic salmon fillets. The effects of the EO water solutions on cell wall structures of L. monocytogenes and on the secondary structure of salmon protein were studied using Fourier Transform Infra-Red (FTIR) spectroscopy. Temperature and time significantly influenced the efficacy of the AEW and NEW. NEW has stronger antimicrobial properties as compared to AEW. The highest bacterial reduction was observed at 65 °C after 10 min for salmon treated with NEW, with a 5.6 log10 CFU/g reduction. Spectral features show that the secondary protein structures in salmon muscle treated with NEW were less affected than tissue treated with AEW as shown in a PCA model. In addition, the FTIR spectra for L. monocytogenes showed that the NEW and AEW affected cell wall properties differently; this might be due to the form of available chlorine in NEW and AEW and to AEW having a lower pH. In general, NEW showed better antimicrobial properties, particularly when combined with mild thermal processing than AEW and also caused less alteration in protein structure. The findings of this study may be used to improve the quality and safety of cured and smoked ready-to-eat fish products.

      PubDate: 2018-04-15T21:52:55Z
  • Antifungal activity and action mechanisms of yeasts isolates from citrus
           against Penicillium italicum
    • Abstract: Publication date: 2 July 2018
      Source:International Journal of Food Microbiology, Volume 276
      Author(s): Tatiane da Cunha, Luriany Pompeo Ferraz, Pitt Paul Wehr, Katia Cristina Kupper
      Penicillium italicum (Blue mold) is a major postharvest disease of citrus. An alternative to controlling the disease is through the use of yeasts. The purpose of the present study was to screen effective yeast antagonists against P. italicum, isolated from soil, leaves, flowers, and citrus fruits, to assess the action mechanisms of the yeast isolates that were demonstrated to be effective for biocontrol, and to identify the most effective yeast isolates for the biocontrol of blue mold. The in vitro assays showed that six yeast strains inhibited up to 90% of the pathogen's mycelial growth. In vivo assays, evaluating the incidence of blue mold on sweet oranges, the strains ACBL-04, ACBL-05, ACBL-10 and ACBL-11 were effective, demonstrating the potential for the blue mold control when preventively applied, whereas the ACBL-08 strain showed a high potential to preventive and curative applications. Additional studies on the modes of action of these yeast strains showed that most of the evaluated yeast strains did not produce antifungal substances, in sufficient quantities to inhibit the pathogen growth. Competition for nutrients was not a biocontrol strategy used by the yeast strains. The ‘killer’ activity might be the main action mechanism involved in P. italicum biocontrol. This study indicated that the multiple modes of action against the pathogen presented by yeasts may explain why these strains provided P. italicum control under in vitro and in vivo conditions. However, further studies in future might be able to elucidate the ‘killer’ activity and its interaction with pathogen cells and the bioproduct production using Candida stellimalicola strains for control postharvest diseases.

      PubDate: 2018-04-15T21:52:55Z
  • Synergistic effect of the combined bio-fungicides ε-poly-l-lysine and
           chitooligosaccharide in controlling grey mould (Botrytis cinerea) in
    • Abstract: Publication date: 2 July 2018
      Source:International Journal of Food Microbiology, Volume 276
      Author(s): Guangzheng Sun, Qichao Yang, Ancheng Zhang, Jia Guo, Xinjie Liu, Yang Wang, Qing Ma
      The antifungal properties and the induction of resistance by ε-poly-l-lysine (ε-PL) and chitooligosaccharide (COS) were examined to find an alternative to synthetic fungicides currently used in the control of the devastating fungal pathogen Botrytis cinerea, the causal agent of grey mould disease of tomatoes. As presented herein, this combined treatment (200 mg/L ε-PL + 400 mg/L COS) was found to have optimal in vitro antifungal activities, achieving an inhibition rate of 90.22%. In vivo assays with these combined bio-fungicides, under greenhouse conditions using susceptible tomato plants, demonstrated good protection against severe grey mould. In field tests, the combined bio-fungicides had a control effect of up to 66.67% against tomato grey mould. To elucidate the mechanisms of the combined bio-fungicide-induced resistance in the tomato, plants were subjected to three treatments: 1) inoculation with B. cinerea after spraying with 200 mg/L ε-PL alone, 2) inoculation with the combined bio-fungicides, and 3) inoculation with 400 mg/L COS alone. Compared to the control (sterile water), increases in salicylic acid (SA) and jasmonic acid (JA) levels and increased phenylalanine ammonia lyase (PAL), peroxidase (POD), and superoxide dismutase (SOD) activities were observed. Catalase (CAT) activity and abscisic acid (ABA) and gibberellin (GA) levels decreased, particularly in the combined bio-fungicide-treated plants. Altogether, these findings reveal that the combined bio-fungicides (200 mg/L ε-PL + 400 mg/L COS) should be an excellent biocontrol agent candidate that combines direct antifungal activity against B. cinerea with plant resistance.

      PubDate: 2018-04-15T21:52:55Z
  • Selection procedure of bioprotective cultures for their combined use with
           High Pressure Processing to control spore-forming bacteria in cooked ham
    • Abstract: Publication date: 2 July 2018
      Source:International Journal of Food Microbiology, Volume 276
      Author(s): Mihanta Ramaroson, Sandrine Guillou, Albert Rossero, Sandrine Rezé, Valérie Anthoine, Nicolas Moriceau, Jean-Luc Martin, Frédérique Duranton, Monique Zagorec
      High Pressure Processing (HPP) and biopreservation can contribute to food safety by inactivation of bacterial contaminants. However these treatments are inefficient against bacterial endospores. Moreover, HPP can induce spore germination. The objective of this study was to select lactic acid bacteria strains to be used as bioprotective cultures, to control vegetative cells of spore-forming bacteria in ham after application of HPP. A collection of 63 strains of various origins was screened for their antagonistic activity against spore-forming Bacillus and Clostridium species and their ability to resist to HPP. Some safety requirements should also be considered prior to their introduction into the food chain. Hence, the selection steps included the assessment of biogenic amine production and antibiotic resistance. No strain produced histamine above the threshold detection level of 50 ppm. From the assessment of antibiotic resistance against nine antibiotics, 14 susceptible strains were kept. Antagonistic action of the 14 strains was then assessed by the well diffusion method against pathogenic or spoilage spore-forming species as Bacillus cereus, Clostridium sp. like botulinum, Clostridium frigidicarnis, and Clostridium algidicarnis. One Lactobacillus curvatus strain and one Lactococcus lactis strain were ultimately selected for their widest inhibitory spectrum and their potential production of bacteriocin. A Lactobacillus plantarum strain was included as control. Their resistance to HPP and ability to regrow during chilled storage was then assessed in model ham liquid medium. Treatments of pressure intensities of 400, 500, and 600 MPa, and durations of 1, 3, 6, and 10 min were applied. After treatment, cultures were incubated at 8 °C during 30 days. Inactivation curves were then fitted by using a reparameterized Weibull model whereas growth curves were modelled with a logistic model. Although the two Lactobacillus strains were more resistant than L. lactis to HPP, the latter was the only strain able to regrow following HPP. The absence of biogenic amine production of this strain after growth on diced cube cooked ham was also shown. In conclusion this L. lactis strain could be selected as representing the best candidate for a promising preservative treatment combining biopreservation and HPP to control spore-forming bacteria in cooked ham.

      PubDate: 2018-04-15T21:52:55Z
  • Revealing the microbiota of marketed edible insects through PCR-DGGE,
           metagenomic sequencing and real-time PCR
    • Abstract: Publication date: 2 July 2018
      Source:International Journal of Food Microbiology, Volume 276
      Author(s): Andrea Osimani, Vesna Milanović, Cristiana Garofalo, Federica Cardinali, Andrea Roncolini, Riccardo Sabbatini, Francesca De Filippis, Danilo Ercolini, Claudia Gabucci, Annalisa Petruzzelli, Franco Tonucci, Francesca Clementi, Lucia Aquilanti
      The present study aimed to identify the microbiota present in six species of processed edible insects produced in Thailand and marketed worldwide via the internet, namely, giant water bugs (Belostoma lutarium), black ants (Polyrhachis), winged termites (alates, Termitoidae), rhino beetles (Hyboschema contractum), mole crickets (Gryllotalpidae), and silkworm pupae (Bombyx mori). For each species, two samples of boiled, dried and salted insects were purchased. The microbial DNA was extracted from the insect samples and subjected to polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), high-throughput sequencing and qualitative real-time PCR assays. The microbiota of the analyzed samples were widely characterized by the presence of spore-forming bacteria mainly represented by the genera Bacillus and Clostridium. Moreover, the genera Anaerobacillus, Paenibacillus, Geobacillus, Pseudomonas, Stenotrophomonas, Massilia, Delftia, Lactobacillus, Staphylococcus, Streptococcus, Vagococcus, and Vibrio were also detected. Real-time PCR allowed for ascertainment of the absence of Coxiella burnetii, Shiga toxin-producing E. coli (STEC), and Pseudomonas aeruginosa in all samples. The results of this study confirm the importance of combining different molecular techniques to characterize the biodiversity of complex ecosystems such as edible insects. The presence of potential human pathogens suggests the need for a careful application of good manufacturing practices during insect processing. This study provides further data that will be useful in risk analyses of edible insects as a novel food source.

      PubDate: 2018-04-15T21:52:55Z
  • Molecular characterization of Aspergillus fumigatus isolated from raw cow
           milk in Argentina
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Gabriela A. Pena, Verónica Alonso, Marina Velasco Manini, M. Pellegrino, Lilia R. Cavaglieri
      Aspergillus fumigatus, the major etiological agent of human and animal aspergillosis, is a gliotoxinogenic species into section Fumigati commonly found in contaminated animal environments. In dairy herds, exposed areas of lactating cows, as mammalian glandule, can be easily contaminated by them. This study was aimed to identify A. fumigatus sensu lato strains (identified based on morphology) isolated from raw cow milk at species level, by morphological and molecular techniques, and to estimate their genetic variability. Forty-five A. fumigatus strains showed similar RAPD profiles (generated with PELF and URP1F primers) to each other and to A. fumigatus sensu stricto reference strains; also, they were almost identical to clinical human and feed-borne A. fumigatus strains included in the assay, since their similarity coefficient ranged from 0.7 to 1.00. Therefore, all strains were characterized as belonging to A. fumigatus sensu stricto species. This result was supported by sequencing the benA gene of selected strains and by maximum parsimony analysis. In addition, RAPD fingerprinting demonstrated intra-specific genetic variability into the A. fumigatus sensu stricto cluster. The results found in this study strengthen the fact that A. fumigatus sensu stricto is the predominant species in the Aspergillus section Fumigati found in animal environments such as dairy herd environments, while other species such as A. novofumigatus, A. fumigatiaffinis, A. udagawae and A. lentulus may be rarely isolated. Since no differences between animal and human strains were observed they can become pathogenic also for farm handlers'. Moreover, the presence of A. fumigatus sensu stricto in raw cow milk is probably a very important risk factor since milk and its by-products are generally indented for human consumption, then gliotoxin could be transferred to them.

      PubDate: 2018-04-15T21:52:55Z
  • UV-C inactivation of foodborne bacterial and viral pathogens and
           surrogates on fresh and frozen berries
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Sophie Butot, Frédérique Cantergiani, Mireille Moser, Julie Jean, Anthony Lima, Lise Michot, Thierry Putallaz, Thomas Stroheker, Sophie Zuber
      Outbreaks of foodborne illness associated with berries often involve contamination with hepatitis A virus (HAV) and norovirus but also bacteria such as Escherichia coli O157:H7 and parasites such as Cyclospora caytanensis. We evaluated the applicability of UV-C to the inactivation of pathogens on strawberries, raspberries and blueberries. Our three-step approach consisted of assessing the chemical safety of UV-C-irradiated berries, evaluating the sensory quality after UV-C treatment and finally studying the inactivation of the target microorganisms. Treatments lasting up to 9 min (4000 mJ cm−2) did not produce detectable levels of furan (<5 μg/kg), a known photolysis product of fructose with genotoxic activity and thus were assessed to be toxicologically safe. No effect on taste or appearance was observed, unless treatment was excessively long. 20 s of treatment (an average fluence of ~ 212 mJ cm−2) reduced active HAV titer by >1 log10 unit in 95% of cases except on frozen raspberries, while 120 s were required to inactivate murine norovirus to this extent on fresh blueberries. The mean inactivation of HAV and MNV was greater on blueberries (2–3 log10) than on strawberries and raspberries (<2 log10). MNV was more sensitive on fresh than on frozen berries, unlike HAV. Inactivation of Salmonella, E. coli O157:H7 and Listeria monocytogenes was poor on all three berries, no treatment reducing viable counts by >1 log10 unit. In most matrices, prolonging the treatment did not improve the result to any significant degree. The effect was near its plateau after 20 s of treatment. These results provide insight into the effectiveness of UV-C irradiation for inactivating bacterial and viral pathogens and surrogates on fresh and frozen berries having different surface types, under different physical conditions and at different levels of contamination. Overall they show that UV-C as single processing step is unsuitable to inactivate significant numbers of foodborne pathogens on berries.

      PubDate: 2018-04-15T21:52:55Z
  • Detection of changes in mould cell wall stress-related gene expression by
           a novel reverse transcription real-time PCR method
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Lucía da Cruz Cabral, Josué Delgado, María J. Andrade, Mar Rodríguez, Alicia Rodríguez
      The cell wall integrity (CWI) pathway is activated in response to cell wall stresses due to different food-related environments. Rho1 is one of the main regulators within such pathway. The objective of this work was to design an easy-to-use RT-qPCR technique for the evaluation of the Rho1 gene expression useful to measure responses to the presence of cell wall stressors such as the antifungal protein PgAFP. Two primer pairs were designed from published conserved regions. Their specificity initially was determined by in silico analysis for several fungal species. After optimising the qPCR, the primer pair Rho1-F1/R2 was selected due to the lowest Cq values obtained and its specificity. The qPCR method showed efficiencies between 97.5% and 100.5%. Applicability of the designed qPCR method was evaluated in the presence of the stressor PgAFP. The PgAFP-resistant Penicillium polonicum and the PgAFP-sensitive Aspergillus flavus showed Rho1 gene over- and under- expression, respectively, indicating that the CWI pathway is activated in the former species but not activated in the latter one in response to the stress caused by PgAFP. This novel qPCR methodology able to detect changes in CWI-related gene expression in filamentous fungi will be useful in future studies to evaluate physiological mould responses to different food environmental challenges.

      PubDate: 2018-04-15T21:52:55Z
  • Application of a phage in decontaminating Vibrio parahaemolyticus in
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Hui Zhang, Zhenquan Yang, Yan Zhou, Hongduo Bao, Ran Wang, Tingwu Li, Maoda Pang, Lichang Sun, Xiaohui Zhou
      Vibrio parahaemolyticus is a major pathogen that is mainly associated with seafood and is a global concern of food safety. With high prevalence of contamination in food, efficient strategy is needed to decontaminate those contaminated foods and control the emergence of vibriosis. In the present study, a V. parahaemolyticus-specific phage vB_VpaS_OMN (designated as phage OMN) was isolated from oyster. Phage OMN had good pH (5–9) and temperature tolerance (<50 °C). Phage OMN exhibited broad host range against isolates of V. parahaemolyticus (20/31). After treatment with phage OMN in the liquid condition for 7 h, the number of V. parahaemolyticus was reduced significantly compared to control treatment. When phage OMN was applied to oyster samples for 48 and 72 h, 90% and 99%, respectively, of V. parahaemolyticus was inactivated on Oyster meat surface. Sequence analysis showed that phage OMN had a 42.202 bp genome and revealed about 59.04% homology with Cronobacter phage vB_CsaP_Ss1. Only 10 CDSs can be predicted based on the GenBank database, while 42% of the CDSs were unique to OMN and had no known function, indicating that phage OMN is a new lytic phage. Fully understanding of the function for the phage genes and the properties of the phage is important for the development of strategies to control V. parahaemolyticus contamination in oysters and disease in aquaculture.

      PubDate: 2018-04-15T21:52:55Z
  • Microbial composition of spoiled industrial-scale Sichuan paocai and
           characteristics of the microorganisms responsible for paocai spoilage
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Feng Zhang, Yao Tang, Yao Ren, Kai Yao, Qiang He, Yuping Wan, Yuanlong Chi
      The microorganisms of spoiled industrial-scale Sichuan paocai (ISSP) were isolated using six types of media, and 16S rRNA and 26S rRNA gene sequence analyses were used to identify the isolates. Meanwhile, the microbial composition was investigated using a culture-independent method through 16S rRNA and ITS sequencing on an Illumina MiSeq platform. The results obtained by these two methods were compared. Furthermore, characteristics of the isolated microorganisms responsible for ISSP spoilage were studied. Sixty-two strains belonging to twenty-three species, including three ammonia-producing genera, two gas-producing genera, two pectinase-producing genera, two cellulase-producing genera, three film-producing genera and one slime-producing genus, were isolated. Lactobacillus, Bacillus, Debaryomyces and Kazachstania were the dominant genera as confirmed through both culture-dependent and culture-independent methods. Bacillus, Paenibacillus, Pichia and Debaryomyces could be the main microorganisms responsible for ISSP spoilage. Bac. licheniformis was closely correlated with the off-flavour of ISSP. Pae. peoriae, Bac. stratosphericus, Bac. toyonensis and Bac. cereus were responsible for tissue softening, and Bac. subtilis, Bac. methylotrophicus, Pic. membranifaciens and Deb. hansenii caused film formation.

      PubDate: 2018-04-15T21:52:55Z
  • Effect of temperature on chlorine dioxide inactivation of Escherichia coli
           O157:H7, Salmonella typhimurium, and Listeria monocytogenes on spinach,
           tomatoes, stainless steel, and glass surfaces
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Sang-Hyun Park, Dong-Hyun Kang
      The objective of this study was to evaluate how treatment temperature influences the solubility of ClO2 gas and the antimicrobial effect of ClO2 gas against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on produce and food contact surfaces. Produce and food contact surfaces inoculated with a combined culture cocktail of three strains each of the three foodborne pathogens were processed in a treatment chamber with 20 ppmv ClO2 gas at 15 or 25 °C under the same conditions of absolute humidity (11.2–12.3 g/m3) for up to 30 min. As treatment time increased, ClO2 gas treatment at 15 °C caused significantly more (p < 0.05) inactivation of the three pathogens than treatment at 25 °C. ClO2 gas treatment at 25 °C for 30 min resulted in 1.15 to 1.54, 1.53 to 1.88, and 1.00 to 1.78 log reductions of the three pathogens on spinach leaves, tomatoes, and stainless steel No.4, respectively. ClO2 gas treatment at 15 °C for 30 min caused 2.53 to 2.88, 2.82 to 3.23, and 2.37 to 3.03 log reductions of the three pathogens on spinach leaves, tomatoes, and stainless steel No.4, respectively. Treatment with ClO2 gas at 25 °C for 20 min resulted in 1.88 to 2.31 log reductions of the three pathogens on glass while >5.91 to 6.82 log reductions of these pathogens occurred after 20 min when treated at 15 °C. Residual ClO2 levels after gas treatment at 15 °C were significantly (p < 0.05) higher than those at 25 °C. The results of this study can help the food processing industry establish optimum ClO2 gas treatment conditions for maximizing the antimicrobial efficacy of ClO2 gas.

      PubDate: 2018-04-15T21:52:55Z
  • Listeria monocytogenes strains show large variations in competitive growth
           in mixed culture biofilms and suspensions with bacteria from food
           processing environments
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Even Heir, Trond Møretrø, Andreas Simensen, Solveig Langsrud
      Interactions and competition between resident bacteria in food processing environments could affect their ability to survive, grow and persist in microhabitats and niches in the food industry. In this study, the competitive ability of L. monocytogenes strains grown together in separate culture mixes with other L. monocytogenes (L. mono mix), L. innocua (Listeria mix), Gram-negative bacteria (Gram− mix) and with a multigenera mix (Listeria + Gram− mix) was investigated in biofilms on stainless steel and in suspensions at 12 °C. The mixed cultures included resident bacteria from processing surfaces in meat and salmon industry represented by L. monocytogenes (n = 6), L. innocua (n = 5) and Gram-negative bacteria (n = 6; Acinetobacter sp., Pseudomonas fragi, Pseudomonas fluorescens, Serratia liquefaciens, Stenotrophomonas maltophilia). Despite hampered in growth in mixed cultures, L. monocytogenes established in biofilms with counts at day nine between 7.3 and 9.0 log per coupon with the lowest counts in the Listeria + G− mix that was dominated by Pseudomonas. Specific L. innocua inhibited growth of L. monocytogenes strains differently; inhibition that was further enhanced by the background Gram-negative microbiota. In these multispecies and multibacteria cultures, the growth competitive effects lead to the dominance of a strong competitor L. monocytogenes strain that was only slightly inhibited by L. innocua and showed strong competitive abilities in mixed cultures with resident Gram-negative bacteria. The results indicates complex patterns of bacterial interactions and L. monocytogenes inhibition in the multibacteria cultures that only partially depend on cell contact and likely involve various antagonistic and bacterial tolerance mechanisms. The study indicates large variations among L. monocytogenes in their competitiveness under multibacterial culture conditions that should be considered in further studies towards understanding of L. monocytogenes persistence in food processing facilities.

      PubDate: 2018-04-15T21:52:55Z
  • Control of Aspergillus carbonarius in grape berries by Lactobacillus
           plantarum: A phenotypic and gene transcription study
    • Abstract: Publication date: 20 June 2018
      Source:International Journal of Food Microbiology, Volume 275
      Author(s): Iliada K. Lappa, Sevasti Mparampouti, Barbara Lanza, Efstathios Z. Panagou
      The in vitro and in situ antifungal activity of Lactobacillus plantarum against the ochratoxigenic fungus Aspergillus carbonarius was investigated in this study. Four different fungal isolates from grape berries were co-cultured with four different strains of L. plantarum on Malt Extract Agar (MEA) plates at 30 °C. Bacterial strains inhibited fungal growth up to 88% and significantly reduced toxin production up to 100%. In addition, L. plantarum was evaluated as biocontrol agent against A. carbonarius growth and OTA production on table grapes. Temporal studies of bacterial antagonism were performed with two different grape cultivars. Artificially wounded and unwounded berries were pre-treated with 108 CFU/mL bacteria and inoculated with 106 spores/mL of A. carbonarius ochratoxigenic isolates. Biocontrol agents displayed high rate of colonization on grapes during 5 days of incubation at 30 °C. Scanning electron microscopy (SEM) also determined the presence of microorganisms on grape surface. Bacterial strains were effective in controlling fungal infection reaching up to 71% inhibition rates. However the presence of wounds on grape skin facilitated infection of berries by A. carbonarius, since unwounded berries showed lower levels of infection. Results also revealed significant reduction in mycotoxin production ranging between 32% and 92%. Transcriptome analysis following exposure to co-cultivation, exhibited differential expression for each gene studied of AcOTAnrps (Aspergillus carbonarius OTA nonribosomal), AcOTApks (Aspergillus carbonarius OTA polyketide synthase) and laeA, emphasizing the significance of strain variability. The genes AcOTAnrps and laeA were most influenced by the presence of L. plantarum. This work is a contribution for the potential biocontrol of toxigenic fungi in table grapes by lactic acid bacteria (LAB). The above findings underline the significance of bacterial strain variability on the effectiveness of biopreservative features of L. plantarum strains.

      PubDate: 2018-04-15T21:52:55Z
  • Comparative analysis of core genome MLST and SNP typing within a European
           Salmonella serovar Enteritidis outbreak
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Madison E. Pearce, Nabil-Fareed Alikhan, Timothy J. Dallman, Zhemin Zhou, Kathie Grant, Martin C.J. Maiden
      Multi-country outbreaks of foodborne bacterial disease present challenges in their detection, tracking, and notification. As food is increasingly distributed across borders, such outbreaks are becoming more common. This increases the need for high-resolution, accessible, and replicable isolate typing schemes. Here we evaluate a core genome multilocus typing (cgMLST) scheme for the high-resolution reproducible typing of Salmonella enterica (S. enterica) isolates, by its application to a large European outbreak of S. enterica serovar Enteritidis. This outbreak had been extensively characterised using single nucleotide polymorphism (SNP)-based approaches. The cgMLST analysis was congruent with the original SNP-based analysis, the epidemiological data, and whole genome MLST (wgMLST) analysis. Combination of the cgMLST and epidemiological data confirmed that the genetic diversity among the isolates predated the outbreak, and was likely present at the infection source. There was consequently no link between country of isolation and genetic diversity, but the cgMLST clusters were congruent with date of isolation. Furthermore, comparison with publicly available Enteritidis isolate data demonstrated that the cgMLST scheme presented is highly scalable, enabling outbreaks to be contextualised within the Salmonella genus. The cgMLST scheme is therefore shown to be a standardised and scalable typing method, which allows Salmonella outbreaks to be analysed and compared across laboratories and jurisdictions.

      PubDate: 2018-04-15T21:52:55Z
  • A comparison of the performance of natural hybrids Saccharomyces
           cerevisiae × Saccharomyces kudriavzevii at low temperatures reveals
           the crucial role of their S. kudriavzevii genomic contribution
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Guadalupe Ortiz-Tovar, Roberto Pérez-Torrado, Ana Cris Adam, Eladio Barrio, Amparo Querol
      Fermentation performance at low temperature is a common approach to obtain wines with better aroma, and is critical in industrial applications. Natural hybrids S. cerevisiae × S. kudriavzevii, isolated from fermentations in cold-climate European countries, have provided an understanding of the mechanisms of adaptation to grow at low temperature. In this work, we studied the performance of 23 S. cerevisiae × S. kudriavzevii hybrids at low temperature (8, 12 and 24 °C) to characterize their phenotypes. Kinetic parameters and spot tests revealed a different ability to grow at low temperature. Interestingly, the genome content of the S. kudriavzevii in hybrids was moderately correlated with a shorter lag phase, and the genetic origin of hybrids influenced their performance at low temperature (8 °C). The parental expression of cold marker genes (NSR1, GUT2 and GPD1) showed that the relative expression of the S. kudriavzevii alleles was higher than the expression of the S. cerevisiae alleles in hybrids with a better growth at low-temperatures. These results suggest that the genomic contribution of S. kudriavzevii to hybrids is important for improving the fitness of these strains at low temperature.

      PubDate: 2018-04-15T21:52:55Z
  • A representative overview of the genetic diversity and lipooligosaccharide
           sialylation in Campylobacter jejuni along the broiler production chain in
           France and its comparison with human isolates
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Amandine Thépault, Muriel Guyard-Nicodème, Valérie Rose, Ségolène Quesne, Marilyne Queguiner, Emmanuelle Houard, Francis Mégraud, Katell Rivoal, Marianne Chemaly
      Campylobacter jejuni is the most common cause of bacterial gastroenteritis worldwide and is associated with post-infectious neuropathies. Moreover, the chicken reservoir is described as the main source of human infection and C. jejuni sialylated lipooligosaccharides seem to play an important role in the pathogenesis of neuropathies. In this study, MultiLocus Sequence Typing (MLST) and Comparative Genomic Fingerprinting using 40 assay genes (CGF40) were used to describe C. jejuni populations within clinical isolates and a representative collection of isolates from French poultry production. In addition, the sialylation of C. jejuni LOS was assessed. Here, we report high levels of genetic diversity among both chicken and human disease C. jejuni populations. The predominance of the ST-21, ST-45, and ST-464 complexes in chicken isolates and of the ST-21, ST-206, and ST-48 complexes in the clinical isolates was observed as were correlations between some MLST and CGF40 genotypes. Furthermore, some C. jejuni genotypes were frequently isolated among clinical cases as well as all along the broiler production chain, suggesting a potentially high implication of chicken in human campylobacteriosis in France. Finally, the LOS classes A, B and C were predominant within clinical C. jejuni isolates supporting the hypothesis of a benefit in infectivity for C. jejuni isolates showing sialylated LOS.

      PubDate: 2018-04-15T21:52:55Z
  • Molecular characterization, antibiotic resistance pattern and biofilm
           formation of Vibrio parahaemolyticus and V. cholerae isolated from
           crustaceans and humans
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Heba A. Ahmed, Rasha M. El Bayomi, Mohamed A. Hussein, Mariam H.E. Khedr, Etab M. Abo Remela, Ahmed M.M. El-Ashram
      Human infection with pathogenic vibrios is associated with contaminated seafood consumption. In the present study, we examined 225 crustaceans collected from retail markets in Egypt. Stool samples from gastroenteritis patients were also examined. Bacteriological and molecular examinations revealed 34 (15.1%) V. parahaemolyticus and 2 (0.9%) V. cholerae from crustaceans, while V. parahaemolyticus isolates were identified in 3 (3%) of the human samples. The virulence-associated genes tdh and/or trh were detected in 5.9% and 100% of the crustacean and human samples, respectively, whereas the two V. cholerae isolates were positive for the ctx and hlyA genes. Antibiotic sensitivity revealed high resistance of the isolates to the used antibiotics and an average MAR index of 0.77. Biofilm formation at different temperatures indicated significantly higher biofilm formation at 37 °C and 25 °C compared with 4 °C. Frequent monitoring of seafood for Vibrio species and their antibiotic, molecular and biofilm characteristics is essential to improve seafood safety.

      PubDate: 2018-04-15T21:52:55Z
  • Antibacterial activity of acidified sodium benzoate against Escherichia
           coli O157:H7, Salmonella enterica, and Listeria monocytogenes in tryptic
           soy broth and on cherry tomatoes
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Huaiqiong Chen, Qixin Zhong
      Concerns about undesirable by-products from chlorine sanitation of fresh produce and the limited efficacy with the presence of organic matter, have led to studies on alternative washing solutions. The aim of this study was to evaluate the antibacterial activities of acidified sodium benzoate (NaB) solutions against Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes in growth medium and on cherry tomatoes. Experimentally, the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs, >3 Log reduction) of NaB against E. coli O157:H7 ATCC 43895, S. Enteritidis, and L. monocytogenes Scott A were determined at pH 7.0–4.0 using micro-broth dilution method and agar plating method, respectively. The reduction of the three bacteria in tryptic soy broth (TSB) by 500 and 1000 ppm NaB at pH 2.0, 2.5 and 3.0 for 30 min at 21 °C was compared. Residual bacterial cocktails inoculated on cherry tomatoes were determined after soaking in 3000 ppm NaB solution adjusted to pH 2.0 for 3 min at 21 °C. Results showed that the MBC of NaB reduced from >10,000 ppm at pH 7.0 to 1000 ppm at pH 4.0 and was identical for the three bacteria. The log reduction of bacteria in TSB indicated that 1000 ppm NaB at pH 2.0 was the most effective in killing the three pathogens. The respective reduction of E. coli O157:H7 and S. enterica cocktails inoculated on cherry tomatoes immersed in 3000 ppm NaB (pH 2.0) at 21 °C for 3 min was 4.99 ± 0.57 and 4.08 ± 0.65 log CFU/g, which was significantly higher (p < 0.05) than the treatments of 200 ppm free chlorine at pH 6.5. Conversely, the reduction of L. monocytogenes on tomatoes by 3000 ppm NaB (4.88 ± 0.73 log CFU/g) was similar (p > 0.05) to 200 ppm chlorine. Furthermore, the reduction of bacterial cocktails on tomatoes by 3000 ppm NaB at pH 2.0 was not affected after adding 1% tomato puree, and bacteria were not detected in NaB washing solutions with and without 1% tomato puree and on following un-inoculated tomatoes. This study showed that acidified NaB solution may be used as an alternative post-harvest wash of produce.

      PubDate: 2018-04-15T21:52:55Z
  • The narrowing down of inoculated communities of coagulase-negative
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Despoina Angeliki Stavropoulou, Emiel Van Reckem, Stefaan De Smet, Luc De Vuyst, Frédéric Leroy
      Coagulase-negative staphylococci (CNS) are involved in colour and flavour formation of fermented meats. Their communities are established either spontaneously, as in some artisan-type products, or using a starter culture. The latter usually consists of Staphylococcus carnosus and/or Staphylococcus xylosus strains, although strains from other CNS species also have potential for application. However, it is not entirely clear how the fitness of alternative starter cultures within a fermented meat matrix compares to conventional ones and how this may be affected by processing conditions. Therefore, the aim of this study was to assess the influence of two key processing conditions, namely temperature and acidity, on the competitiveness of a cocktail of five different strains of CNS belonging to species that are potentially important for meat fermentation (Staphylococcus xylosus 2S7-2, S. carnosus 833, Staphylococcus epidermidis ATCC 12228, Staphylococcus equorum DFL-S19, and Staphylococcus saprophyticus FPS1). To this end, fermented meat models consisting of cured meat batters with initial pH values of 5.3, 5.5, or 5.7 were inoculated with these strains, stuffed in containers, and incubated at 23, 30, or 37 °C. Both the pH level and the temperature influenced the composition of the CNS communities, giving a competitive advantage to the best adapted species. Staphylococcus xylosus preferred low temperature and mild acidity, whereas an elevated temperature selected for S. epidermidis and a low pH for S. carnosus. Under the conditions tested, S. saprophyticus and S. equorum were outcompeted by the three other CNS species. Hence, CNS communities in fermented meats are not only established based on the initial presence of specific species in the meat batter but also by their subsequent adaptation to the processing conditions during fermentation, potentially overruling the use of starter cultures.

      PubDate: 2018-04-15T21:52:55Z
  • Pervasiveness of Staphylococcus carnosus over Staphylococcus xylosus is
           affected by the level of acidification within a conventional meat starter
           culture set-up
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Despoina Angeliki Stavropoulou, Hannelore De Maere, Alberto Berardo, Bente Janssens, Panagiota Filippou, Luc De Vuyst, Stefaan De Smet, Frédéric Leroy
      Staphylococcus carnosus and Staphylococcus xylosus are commonly used, individually or in combination, within conventional starter cultures for the purposes of colour and flavour development during meat fermentation. Yet, little is known about the relative importance of both species under different processing conditions. The present study aimed at investigating the competitiveness of S. carnosus within a meat starter culture under different acidification profiles. The experimental set-up involved a gradient of decreasing experimental control but increasing realism, ranging from liquid meat fermentation models in a meat simulation medium, over solid mince-based meat fermentation models, to fermented sausage production on pilot-scale level. In general, S. carnosus gained a fitness advantage over S. xylosus in the most acidified variants of each set-up. In contrast, increasing persistence of S. xylosus was seen at the mildest acidification profiles, especially when approximating actual meat fermentation practices. Under such conditions, S. carnosus was reduced to co-prevalence in the mince-based meat fermentation models and was fully outcompeted on pilot-scale level. The latter was even the case when no S. xylosus starter culture was added, whereby S. carnosus was overpowered by staphylococci that originated from the meat background (mostly S. xylosus strains). The results of the present study suggested that conventional starter cultures behave differently when applied in different technological set-ups or using different recipes, with possible repercussions on fermented meat product quality.

      PubDate: 2018-04-15T21:52:55Z
  • Fermented meats (and the symptomatic case of the Flemish food pyramid):
           Are we heading towards the vilification of a valuable food group'
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274
      Author(s): Frédéric Leroy, Teresa Aymerich, Marie-Christine Champomier-Vergès, Luca Cocolin, Luc De Vuyst, Mónica Flores, Françoise Leroi, Sabine Leroy, Régine Talon, Rudi F. Vogel, Monique Zagorec

      PubDate: 2018-04-15T21:52:55Z
  • ICFMH Announcement
    • Abstract: Publication date: 2 June 2018
      Source:International Journal of Food Microbiology, Volume 274

      PubDate: 2018-04-15T21:52:55Z
  • Fungal community, Fusarium head blight complex and secondary metabolites
           associated with malting barley grains harvested in Umbria, central Italy
    • Abstract: Publication date: 20 May 2018
      Source:International Journal of Food Microbiology, Volume 273
      Author(s): Giovanni Beccari, Maria Teresa Senatore, Francesco Tini, Michael Sulyok, Lorenzo Covarelli
      In recent years, due to the negative impact of toxigenic mycobiota and of the accumulation of their secondary metabolites in malting barley grains, monitoring the evolution of fungal communities in a certain cultivation area as well as detecting the different mycotoxins present in the raw material prior to malting and brewing processes have become increasingly important. In this study, a survey was carried out on malting barley samples collected after their harvest in the Umbria region (central Italy). Samples were analyzed to determine the composition of the fungal community, to identify the isolated Fusarium species, to quantify fungal secondary metabolites in the grains and to characterize the in vitro mycotoxigenic profile of a subset of the isolated Fusarium strains. The fungal community of barley grains was mainly composed of microorganisms belonging to the genus Alternaria (77%), followed by those belonging to the genus Fusarium (27%). The Fusarium head blight (FHB) complex was represented by nine species with the predominance of Fusarium poae (37%), followed by Fusarium avenaceum (23%), Fusarium graminearum (22%) and Fusarium tricinctum (7%). Secondary metabolites biosynthesized by Alternaria and Fusarium species were present in the analyzed grains. Among those biosynthesized by Fusarium species, nivalenol and enniatins were the most prevalent ones. Type A trichothecenes (T-2 and HT-2 toxins) as well as beauvericin were also present with a high incidence. Conversely, the number of samples contaminated with deoxynivalenol was low. Conjugated forms, such as deoxynivalenol-3-glucoside and HT-2-glucoside, were detected for the first time in malting barley grains cultivated in the surveyed area. In addition, strains of F. avenaceum and F. tricinctum showed the ability to biosynthesize in vitro high concentrations of enniatins. The analysis of fungal secondary metabolites, both in the grains and in vitro, revealed also the presence of other compounds, for which further investigations will be required. The combination of microbiological analyses, of molecular biology assays and of multi-mycotoxin screening shed light on the complexity of the fungal community and its secondary metabolites released in malting barley.

      PubDate: 2018-04-15T21:52:55Z
  • Isolation and characterization of microorganisms and volatiles associated
           with Moroccan saffron during different processing treatments
    • Abstract: Publication date: 20 May 2018
      Source:International Journal of Food Microbiology, Volume 273
      Author(s): Francesco Fancello, Giacomo Petretto, Maria Lina Sanna, Giorgio Pintore, Mounira Lage, Severino Zara
      Saffron may be spoiled by a variety of microorganisms during cultivation, harvesting, and post harvesting. As saffron can be dried and stored in different ways, this preliminary study explored the natural microbiota present in Moroccan saffron when subjected to different drying techniques. An analysis of the carotenoid-derived volatiles present in the saffron was also carried out. The culturable microbiota of the saffron samples dried using different methods, namely in the shade (also called natural), in the sun, or in the oven, were studied using classical and molecular approaches. The effect of the drying methods on head-space chemical volatiles was also determined. Eighty-two isolates grown in the different culture media were chosen from the colonies, and genotype analysis grouped the microorganisms into 58 clusters, revealing a wide diversity. Out of the 82 isolates, 75 belonged to the Bacillaceae family. The other isolates were distributed within the Dietziaceae, Paenibacillaceae and Carnobacteriaceae families. The dominant species was Bacillus simplex, which was detected in all samples, regardless of the drying method used. Lysinibacillus macroides was dominant in the sun-dried saffron. No pathogens were isolated, but an isolate belonging to Dietzia maris, a potential human pathogenic species, was detected. The biodiversity indexes were linked to the drying method and generally decreased as the intensity of the treatment increased. The results of this preliminary work show that the different drying methods strongly influenced the microbiota and affect the saffron volatile profile. Further analysis will be needed to determine possible effects of selected microbiota on saffron volatiles.

      PubDate: 2018-04-15T21:52:55Z
  • ICFMH Announcement
    • Abstract: Publication date: 20 May 2018
      Source:International Journal of Food Microbiology, Volume 273

      PubDate: 2018-04-15T21:52:55Z
  • ICFMH Announcement
    • Abstract: Publication date: 2 May 2018
      Source:International Journal of Food Microbiology, Volume 272

      PubDate: 2018-04-15T21:52:55Z
  • Quantification and colonisation dynamics of Escherichia coli O157:H7
           inoculation of microgreens species and plant growth substrates
    • Abstract: Publication date: 20 May 2018
      Source:International Journal of Food Microbiology, Volume 273
      Author(s): Kathryn M. Wright, Nicola J. Holden
      Microgreens are edible plants used in food preparation for their appealing flavours and colours. They are grown beyond the point of harvest of sprouted seeds, and normally include the cotyledons and first true leaves. Their method of production is similar to sprouted seeds, which is known to be favourable for growth of microbial pathogens, although there is little data on the potential of food-borne pathogens such as Shigatoxigenic Escherichia coli (STEC) to colonise these plants. We found colonisation of nine different species of microgreen plants by STEC (isolate Sakai, stx−), with high levels of growth over five days, of approximately 5 orders of magnitude, for plants propagated at 21 °C. STEC (Sakai) formed extensive colonies on external tissue, with some evidence for internalisation via stomatal pores. Several factors impacted the level of colonisation: (1) plant tissue type such that for broccoli microgreens, the highest levels of STEC (Sakai) occurred on cotyledons compared to the true leaf and hypocotyl; (2) the route of contamination such that higher levels occurred with contaminated irrigation water compared to direct seed contamination; (3) inoculation dose, although only at low levels of inoculation (3 log10) compared to medium (5 log10) or high (7 log10) levels; (4) environmental factors, including to some extent humidity, but also plant growth substrate types. It was also evident that a starvation response was induced in STEC (Sakai) in low-nutrient plant irrigation medium. Together these data show that microgreens represent a potential hazard of contamination by food-borne pathogens, and to mitigate the risk, they should be considered in the same manner as sprouted seeds.

      PubDate: 2018-03-19T20:45:16Z
  • Glycerol metabolism induces Listeria monocytogenes biofilm formation at
           the air-liquid interface
    • Abstract: Publication date: 20 May 2018
      Source:International Journal of Food Microbiology, Volume 273
      Author(s): Natalia Crespo Tapia, Heidy M.W. den Besten, Tjakko Abee
      Listeria monocytogenes is a food-borne pathogen that can grow as a biofilm on surfaces. Biofilm formation in food-processing environments is a big concern for food safety, as it can cause product contamination through the food-processing line. Although motile aerobic bacteria have been described to form biofilms at the air-liquid interface of cell cultures, to our knowledge, this type of biofilm has not been described in L. monocytogenes before. In this study we report L. monocytogenes biofilm formation at the air-liquid interface of aerobically grown cultures, and that this phenotype is specifically induced when the media is supplemented with glycerol as a carbon and energy source. Planktonic growth, metabolic activity assays and HPLC measurements of glycerol consumption over time showed that glycerol utilization in L. monocytogenes is restricted to growth under aerobic conditions. Gene expression analysis showed that genes encoding the glycerol transporter GlpF, the glycerol kinase GlpK and the glycerol 3-phosphate dehydrogenase GlpD were upregulated in the presence of oxygen, and downregulated in absence of oxygen. Additionally, motility assays revealed the induction of aerotaxis in the presence of glycerol. Our results demonstrate that the formation of biofilms at the air-liquid interface is dependent on glycerol-induced aerotaxis towards the surface of the culture, where L. monocytogenes has access to higher concentrations of oxygen, and is therefore able to utilize this compound as a carbon source.

      PubDate: 2018-03-19T20:45:16Z
  • Evaluation of gaseous chlorine dioxide for the inactivation of Tulane
           virus on blueberries
    • Abstract: Publication date: 20 May 2018
      Source:International Journal of Food Microbiology, Volume 273
      Author(s): David H. Kingsley, Rafael E. Pérez-Pérez, Brendan A. Niemira, Xuetong Fan
      To determine the effectiveness of gaseous chlorine dioxide (gClO2) against a human norovirus surrogate on produce, gClO2 was generated and applied to Tulane virus-coated blueberries in a 240 ml-treatment chamber. gClO2 was produced by an acidifying sodium chlorite solution. Initial assessments indicated that blueberries treated with gClO2 generated from ≤1 mg acidified sodium chlorite in the small chamber appeared unaffected while gClO2 generated from ≥10 mg of acidified sodium chlorite solution altered the appearance and quality of the blueberries. Treatments of inoculated blueberries with gClO2 generated from 0.1 mg sodium chlorite reduced the virus populations by >1 log after exposure for 30 to 330 min. For the 1 mg sodium chlorite treatments, the virus populations were reduced by >2.2 log after 15 min exposure and to non-detectable levels (>3.3 logs reductions) after 180 min exposure. Measured concentrations of gClO2 peaked in the treatment chamber at 0.9 μg/l after 10 min for 0.1 mg treatments and 600 μg/l after around 20 min for 1 mg treatment. Overall results indicate that gClO2 could be a feasible waterless intervention for blueberries and other produce.

      PubDate: 2018-03-19T20:45:16Z
  • The bacterial biota of laboratory-reared edible mealworms (Tenebrio
           molitor L.): From feed to frass
    • Abstract: Publication date: 2 May 2018
      Source:International Journal of Food Microbiology, Volume 272
      Author(s): Andrea Osimani, Vesna Milanović, Federica Cardinali, Cristiana Garofalo, Francesca Clementi, Marina Pasquini, Paola Riolo, Sara Ruschioni, Nunzio Isidoro, Nino Loreto, Elena Franciosi, Kieran Tuohy, Annalisa Petruzzelli, Martina Foglini, Claudia Gabucci, Franco Tonucci, Lucia Aquilanti
      Tenebrio molitor represents one of the most popular species used for the large-scale conversion of plant biomass into protein and is characterized by high nutritional value. In the present laboratory study, the bacterial biota characterizing a pilot production chain of fresh T. molitor larvae was investigated. To this end, different batches of fresh mealworm larvae, their feeding substrate (wheatmeal) and frass were analyzed by viable microbial counts, PCR-DGGE and Illumina sequencing. Moreover, the occurrence of Coxiella burnetii, Pseudomonas aeruginosa and Shiga toxin-producing E. coli (STEC) was assessed through qualitative real-time PCR assays. Microbial viable counts highlighted low microbial contamination of the wheatmeal, whereas larvae and frass were characterized by high loads of Enterobacteriaceae, lactic acid bacteria, and several species of mesophilic aerobes. Spore-forming bacteria were detected to a lesser extent in all the samples. The combined molecular approach used to profile the microbiota confirmed the low microbial contamination of wheatmeal and allowed the detection of Enterobacter spp., Erwinia spp., Enterococcus spp. and Lactococcus spp. as dominant genera in both larvae and frass. Moreover, Klebsiella spp., Pantoea spp., and Xenorhabdus spp. were found to be in the minority. Entomoplasmatales (including Spiroplasma spp.) constituted a major fraction of the microbiota of one batch of larvae. From the real-time PCR assays, no sample was positive for either C. burnetii or STEC, whereas P. aeruginosa was detected in one sample of frass. Based on the overall results, two sources of microbial contamination were hypothesized, namely feeding with wheatmeal and vertical transmission of microorganisms from mother to offspring. Since mealworms are expected to be eaten as a whole, the overall outcomes collected in this laboratory study discourage the consumption of fresh mealworm larvae. Moreover, microbial loads and the absence of potential pathogens known to be associated with this insect species should be carefully assessed in order to reduce the minimum risk for consumers, by identifying the most opportune processing methods (e.g., boiling, frying, drying, etc.).

      PubDate: 2018-03-19T20:45:16Z
  • Investigation of the bacteriophage community in induced lysates of
           undefined mesophilic mixed-strain DL-cultures using classical and
           metagenomic approaches
    • Abstract: Publication date: 2 May 2018
      Source:International Journal of Food Microbiology, Volume 272
      Author(s): Musemma K. Muhammed, Mette L. Olsen, Witold Kot, Horst Neve, Josué L. Castro-Mejía, Thomas Janzen, Lars H. Hansen, Dennis S. Nielsen, Søren J. Sørensen, Knut J. Heller, Finn K. Vogensen
      To investigate the notion that starter cultures can be a reservoir of bacteriophages (phages) in the dairy environment, strains of three DL-starters (undefined mesophilic mixed-strain starters containing Lactococcus lactis subsp. lactis biovar. diacetylactis and Leuconostoc species) were selected and induced by mitomycin C, and the whole starters were induced spontaneously as well as by mitomycin C. Frequency of induction of 17%, 26% and 12% was estimated among the isolates of the three starters, with majority of the induced phages mostly showing morphological similarity to known P335 phages, and with a fraction of them showing atypical features. Sequences of P335 quasi-species phages were found to be the most frequent entities in almost all metaviromes derived from the induced lysates. However, sequences of Sk1virus phages (previously 936 phages) were emerged as the predominant entities following spontaneous induction of one of the starters, suggesting a phage-carrier state. Sequences of other phages such as 949, 1706, C2virus (previously c2 phages) and Leuconostoc species could also be observed but with a lower relative frequency. Taken together, the majority of the P335 quasi-species phages could represent the induced viral community of the starters and the remaining phage groups mainly represent the background ambient viral community.

      PubDate: 2018-03-19T20:45:16Z
  • New and known zoonotic nematode larvae within selected fish species from
           Queensland waters in Australia
    • Abstract: Publication date: 2 May 2018
      Source:International Journal of Food Microbiology, Volume 272
      Author(s): Shokoofeh Shamsi, Eleanor Steller, Yuchi Chen
      Zoonotic fish-borne nematodes are a significant and growing global health concern. However, in Australia their occurrence and geographical distribution are not well known. Moreton Bay in Queensland, Australia, is a popular tourist destination for domestic and international visitors where seafood is a popular food item. The aim of this study was to determine the occurrence of zoonotic nematodes within four commercially significant teleost fish species from Moreton Bay; Surf Bream, Sea Mullet, Yellow-Fin Tripod fish and Gold-Lined Sea Bream. Overall, 34.03% of fish examined (n = 144) were found to be a host to at least one parasitic nematode. The seasonal dynamics and prevalence of nematode infection was tested by statistical means. Results indicated a significant difference in seasonal infection for Surf Bream (p < 0.005) only. Several potentially zoonotic larval morphotypes were found, including Contracaecum types I and II, and Terranova type II (Family Anisakidae), and Hysterothylacium types VI and XIV and a new Hysterothylacium larval type herein assigned as type XVII (Family Raphidascarididae). ITS sequence data showed that some Contracaecum type II and Hysterothylacium types VI found in the present study are genetically distinct from those previously reported. The new genotypes were assigned to Contracaecum type II Genotype B and Hysterothylacium type VI, Genotypes B and C. This study provides essential information for future research on specific identification and differentiation of infective stages of zoonotic nematoda in edible fish.

      PubDate: 2018-03-19T20:45:16Z
  • Filamentous fungi associated with natural infection of noble rot on
           withered grapes
    • Abstract: Publication date: 2 May 2018
      Source:International Journal of Food Microbiology, Volume 272
      Author(s): M. Lorenzini, B. Simonato, F. Favati, P. Bernardi, A. Sbarbati, G. Zapparoli
      The effects of noble rot infection of grapes on the characteristics of different types of wine, including Italian passito wine, are well known. Nevertheless, there is still little information on filamentous fungi associated with noble-rotten grapes. In this study, withered Garganega grapes for passito wine production, naturally infected by noble rot, were analyzed and compared to sound grapes. Skin morphology and fungal population on berry surfaces were analyzed. Scanning electron microscopy analysis revealed microcracks, germination conidia and branched hyphae on noble-rotten berries. Penicillium, Aureobasidium and Cladosporium were the most frequent genera present. Analysis of single berries displayed higher heterogeneity of epiphytic fungi in those infected by noble-rot than in sound berries. Penicillium adametzoides, Cladosporium cladospoirioides and Coniochaeta polymorpha were recovered. These, to the best of our knowledge, had never been previously isolated from withered grapes and, for C. polymorpha, from grapevine. This study provided novel data on noble rot mycobiota and suggests that fungi that co-habit with B. cinerea could have an important role on grape and wine quality.

      PubDate: 2018-03-19T20:45:16Z
  • Influence of ochratoxin A on adaptation of Penicillium nordicum on a
           NaCl-rich dry-cured ham-based medium
    • Abstract: Publication date: 2 May 2018
      Source:International Journal of Food Microbiology, Volume 272
      Author(s): Josué Delgado, Lucía da Cruz Cabral, Mar Rodríguez, Alicia Rodríguez
      Iberian dry-cured ham is an important meat product with high consumption worldwide. The special ecological conditions occurring throughout its ripening favour surface colonisation of filamentous fungi. Normally, moulds contribute to the development of the sensory qualities of the ham; however, some toxigenic species, such as Penicillium nordicum, are able to successfully adapt to the NaCl-rich environment found in dry-cured ham and produce ochratoxin A (OTA) in this product. Moreover, it was suggested that the biosynthesis of OTA by P. nordicum itself may support the adaptation to this food environment. However, this mechanism has not been completely elucidated yet. The objective of this work was to evaluate the influence of different concentrations of commercial OTA (cOTA, at 0, 0.2, 1 and 5 ppb) on growth rate, biosynthetic- and stress-related gene expression and OTA production by two P. nordicum strains (Pn15 and Pn69) on dry-cured ham based-media. Two NaCl conditions (0% and 10%) were evaluated for each cOTA level. In general, no intra-strain and inter-strain differences in growth rates were found among the conditions tested. The stress-related Hog1 gene expression of the strain Pn15 was affected by cOTA and NaCl concentration whilst the strain Pn69 was not affected by these variables. The expression of OTA-related otapks and otanps genes of the strain Pn15 was affected by several NaCl and cOTA combinations. However, the strain Pn69 showed no differences in relative gene expression. Regarding to OTA production, different behaviours were displayed by the two strains. The strain Pn15, which produced high OTA amounts by itself, produced OTA without the necessity of the presence of NaCl or cOTA as stressors. However, the presence of cOTA triggers OTA production by the weak OTA producing Pn69 in the absence of NaCl. In addition, although a moderate correlation was found between the expression of the OTA-related genes and mycotoxin produced by P. nordicum in the absence of NaCl, none was obtained between Hog1 gene expression and mycotoxin production. This study is a step forward for a better understanding of the ability of P. nordicum producers of OTA to colonise NaCl-rich habitats such as Iberian ham for proposing actions to minimise OTA contamination in this meat product.

      PubDate: 2018-03-07T20:18:18Z
  • Assessing the functionality and genetic diversity of lactococcal prophages
    • Abstract: Publication date: Available online 1 March 2018
      Source:International Journal of Food Microbiology
      Author(s): Philip Kelleher, Jennifer Mahony, Katharina Schweinlin, Horst Neve, Charles M. Franz, Douwe van Sinderen
      Lactococcus lactis is a lactic acid bacterium that is intensively and globally exploited in commercial dairy food fermentations. Though the presence of prophages in lactococcal genomes is widely reported, only limited studies pertaining to the stability of prophages in lactococcal genomes have been performed. The current study reports on the complete genome exploration of thirty lactococcal strains for the presence of potentially intact prophages, so as to assess their genomic diversity and the associated risk or benefit of harbouring such prophages. Genomic predictions partnered with mitomycin C inductions and flow cytometric analysis of the induced cell lysates confirmed that only four strains consistently produced intact phage particles, thus indicating a relatively low risk associated with prophage induction in the fermentation setting. Our analysis revealed the widespread presence of putative phage-resistance systems encoded by lactococcal prophages, thus highlighting the potential benefits for host fitness. Many of the identified lactococcal prophages belong to the so-called P335 phage group, while a large group of phage remnants bear similarity to members of the 936 phage group. The P335 phage group was recently shown to encompass four distinct genetic lineages. Our study identified an additional lineage, thus expanding the diversity of this industrially significant phage group.

      PubDate: 2018-03-07T20:18:18Z
  • Genetic and phenotypic analysis of carbohydrate metabolism and transport
           in Lactobacillus reuteri
    • Abstract: Publication date: Available online 27 February 2018
      Source:International Journal of Food Microbiology
      Author(s): Xin Zhao, Michael G. Gänzle
      Lactobacilli derive metabolic energy mainly from carbohydrate fermentation. Homofermentative and heterofermentative lactobacilli exhibit characteristic differences in carbohydrate transport and regulation of metabolism, however, enzymes for carbohydrate transport in heterofermentative lactobacilli are poorly characterized. This study aimed to identify carbohydrate active enzymes in the L. reuteri strains LTH2584, LTH5448, TMW1.656, TMW1.112, 100-23, mlc3, and lpuph by phenotypic analysis and comparative genomics. Sourdough and intestinal isolates of L. reuteri displayed no difference in the number and type of carbohydrate-active enzymes encoded in the genome. Predicted sugar transporters encoded by genomes of L. reuteri strains were secondary carriers and most belong to the major facilitator superfamily. The quantification of gene expression during growth in sourdough and in chemically defined media corresponded to the predicted function of the transporters MalT, ScrT and LacS as carriers for maltose, sucrose, and lactose or raffinose, respectively. The genotype for sugar utilization matched the fermentation profile of 39 sugars for L. reuteri strains, and indicated preference for maltose, sucrose, raffinose and (iso)-malto-oligosaccharides, which are available in sourdough and in the upper intestine of rodents. Pentose utilization in L. reuteri species was strain-specific but independent of the origin or phylogenetic position of isolates. Two glycosyl hydrolases, licheninase (EC and endo-1, 4-β-galactosidase (EC were identified based on conserved domains. In conclusion, the study identified the lack of PTS systems, preference for secondary carriers for carbohydrate transport, and absence of carbon catabolite repression as characteristic features of the carbohydrate metabolism in the heterofermentative L. reuteri.

      PubDate: 2018-03-07T20:18:18Z
  • Assessment of intraspecies variability in fungal growth initiation of
           Aspergillus flavus and aflatoxin B1 production under static and changing
           temperature levels using different initial conidial inoculum levels
    • Abstract: Publication date: 2 May 2018
      Source:International Journal of Food Microbiology, Volume 272
      Author(s): Laila Aldars-García, Sonia Marín, Vicente Sanchis, Naresh Magan, Angel Medina
      Intraspecies variability in fungal growth and mycotoxin production has important implications for food safety. Using the Bioscreen C we have examined spectrophotometrically intraspecies variability of A. flavus using 10 isolates under different environments, including temperature shifts, in terms of growth and aflatoxin B1 (AFB1) production. Five high and five low AFB1 producers were examined. The study was conducted at 5 isothermal conditions (from 15 to 37 °C) and 4 dynamic scenarios (between 15 and 30 °C). The experiments were carried out in a semisolid YES medium at 0.92 aw and two inoculum levels, 102 and 103 spores/mL. The Time to Detection (TTD) of growth initiation was determined and modelled as a function of temperature through a polynomial equation and the model was used to predict TTD under temperature upshifts conditions using a novel approach. The results obtained in this study have shown that a model can be developed to describe the effect of temperature upshifts on the TTD for all the studied isolates and inoculum levels. Isolate variability increased as the growth conditions became more stressful and with a lower inoculum level. Inoculum level affected the intraspecies variability but not the repeatability of the experiments. In dynamic conditions, isolate responses depended both on the temperature shift and, predominantly, the final temperature level. AFB1 production was highly variable among the isolates and greatly depended on temperature (optimum temperature at 30–35 °C) and inoculum levels, with often higher production with lower inoculum. This suggests that, from an ecological point of view, the potential isolate variability and interaction with dynamic conditions should be taken into account in developing strategies to control growth and predicting mycotoxin risks by mycotoxigenic fungi.

      PubDate: 2018-02-25T19:58:39Z
  • Applicability of Lactococcus hircilactis and Lactococcus laudensis as
           dairy cultures
    • Authors: Flavio Tidona; Aurora Meucci; Milena Povolo; Valeria Pelizzola; Miriam Zago; Giovanna Contarini; Domenico Carminati; Giorgio Giraffa
      Abstract: Publication date: Available online 13 February 2018
      Source:International Journal of Food Microbiology
      Author(s): Flavio Tidona, Aurora Meucci, Milena Povolo, Valeria Pelizzola, Miriam Zago, Giovanna Contarini, Domenico Carminati, Giorgio Giraffa
      The aim of this study was to evaluate whether Lactococcus hircilactis and Lactococcus laudensis can be used as starter cultures. To this end, the two lactococci were characterized for traits of technological and functional interest. Tests in milk included growth at 20, 25, 30, and 37 °C, flavor production, antioxidant (AO) activity, folate and exopolysaccharide (EPS) production. At 30 °C, which resulted the best growth temperature for both strains, Lc. hircilactis and Lc. laudensis lowered the pH of the milk to 4.8 and 5.5, respectively, after 24 h of incubation. Sugar and organic acid composition indicated a higher lactose utilization, coupled with a higher lactate accumulation, by Lc. hircilactis, while galactose was completely consumed by both species. Both strains showed a Cit− phenotype after growth in a selective medium containing citrate as the sole carbon source. Nevertheless, a small amount of citrate was used by both lactococci when grown in milk. The two strains were characterized by a different flavor production, showed high AO activity, and produced small amounts of EPS (~30 mg/L). Lactococcus laudensis showed a weak proteolytic activity while Lc. hircilactis was able to accumulate folate at levels four times higher than uninoculated milk. When the two lactococci were tested as starter cultures in small-scale cheesemaking trials, cheeses resulted of satisfying quality and contained amounts of ethanol, acetic acid, diacetyl and acetoin higher than controls, obtained using a commercial culture. The application of Lc. hircilactis and Lc. laudensis as aromatic cultures in cheesemaking is proposed.

      PubDate: 2018-02-15T19:45:16Z
      DOI: 10.1016/j.ijfoodmicro.2018.02.015
  • Antifungal activity of plant-derived compounds and their synergism against
           major postharvest pathogens of longan fruit in vitro
    • Authors: P. Suwanamornlert; S. Sangchote; W. Chinsirikul; A. Sane; V. Chonhenchob
      Abstract: Publication date: Available online 10 February 2018
      Source:International Journal of Food Microbiology
      Author(s): P. Suwanamornlert, S. Sangchote, W. Chinsirikul, A. Sane, V. Chonhenchob
      The aim of this study was to find alternatives to conventional synthetic fungicides to control postharvest decay of longan fruit. The antifungal potential of thymol, carvacrol and trans-cinnamaldehyde was evaluated against four major longan pathogens, Lasiodiplodia spp., Phomopsis spp., Pestalotiopsis spp. and Geotrichum candidum, using vapor phase and direct contact methods. The vapor phase of all active compounds was more effective on fungal growth than direct contact. A volatile vapor of thymol and carvacrol had strong antifungal activity against the tested fungi, exhibiting minimum inhibitory concentration (MIC) in the range of 40 to 80 mg/L air; trans-cinnamaldehyde showed the least efficiency, with MIC ranging from 80 to 160 mg/L air for G. candidum and Phomopsis spp., while it could not inhibit Lasiodiplodia spp. and Pestalotiopsis spp. at 160 mg/L air. The minimum fungicidal concentration (MFC) of thymol and carvacrol varied from 40 to 80 mg/L air, while trans-cinnamaldehyde completely inhibited the mycelial growth of the tested fungi at higher concentrations. Mycelial growth of all tested fungi decreased with increasing active compound concentration, except for trans-cinnamaldehyde. Thymol proved to be the most effective compound against the four tested fungi, with effective concentration 50 (EC50) of 5.68 ± 0.59, 6.86 ± 0.52, 8.27 ± 0.22 and 9.99 ± 1.28 mg/L air for Lasiodiplodia spp., Phomopsis spp., Pestalotiopsis spp. and G. candidum, respectively. Fungal growth curves were adequately fitted (0.958 < R 2 < 0.996) by a modified Gompertz model. For all tested fungi, the lag phase (λ) of fungal mycelia exposed to thymol and carvacrol increased, while the maximum colony diameter (A) and maximum growth rate (v m ) decreased. A combination of thymol and carvacrol exhibited an antagonistic effect against G. candidum but an indifferent effect against Lasiodiplodia spp., Phomopsis spp. and Pestalotiopsis spp.

      PubDate: 2018-02-15T19:45:16Z
      DOI: 10.1016/j.ijfoodmicro.2018.02.009
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