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  Subjects -> BIOLOGY (Total: 2940 journals)
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MICROBIOLOGY (247 journals)                  1 2     

Showing 1 - 0 of 0 Journals sorted alphabetically
Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 5)
Addiction Genetics     Open Access   (Followers: 5)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 15)
Advances in Microbiology     Open Access   (Followers: 15)
Advances in Molecular Imaging     Open Access   (Followers: 1)
African Journal of Clinical and Experimental Microbiology     Open Access  
African Journal of Microbiology Research     Open Access   (Followers: 1)
Algorithms for Molecular Biology     Open Access   (Followers: 4)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 14)
American Journal of Microbiological Research     Open Access   (Followers: 1)
American Journal of Microbiology     Open Access   (Followers: 12)
American Journal of Molecular Biology     Open Access   (Followers: 2)
American Journal of Stem Cell Research     Open Access   (Followers: 2)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 5)
Annals of Microbiology     Hybrid Journal   (Followers: 6)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 29)
Antimicrobial Agents and Chemotherapy     Hybrid Journal   (Followers: 17)
Applied and Environmental Microbiology     Hybrid Journal   (Followers: 37)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 15)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 53)
Aquatic Microbial Ecology     Hybrid Journal   (Followers: 2)
Archives of Microbiology     Hybrid Journal   (Followers: 7)
Avicenna Journal of Clinical Microbiology and Infection     Open Access   (Followers: 1)
Bangladesh Journal of Medical Microbiology     Open Access  
Beneficial Microbes     Full-text available via subscription   (Followers: 1)
Bio-Research     Full-text available via subscription  
BioArchitecture     Full-text available via subscription  
Biocell     Open Access  
Bioethanol     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 6)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Biomolecular Detection and Quantification     Open Access  
Biomolecules     Open Access   (Followers: 1)
Biotechnology and Molecular Biology Reviews     Open Access  
BMC Microbiology     Open Access   (Followers: 8)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases and Medical Microbiology     Open Access   (Followers: 1)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 3)
Cell Biology : Research & Therapy     Hybrid Journal   (Followers: 2)
Cell Host & Microbe     Full-text available via subscription   (Followers: 11)
Cell Medicine     Open Access   (Followers: 3)
Cell Regeneration     Open Access   (Followers: 1)
Cell Stem Cell     Full-text available via subscription   (Followers: 27)
CellBio     Open Access  
Cells     Open Access   (Followers: 1)
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 10)
Cellular and Molecular Biology Letters     Open Access   (Followers: 1)
Cellular Microbiology     Hybrid Journal   (Followers: 7)
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: 15)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 4)
Clinical Microbiology Reviews     Hybrid Journal   (Followers: 14)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 10)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 11)
Current Clinical Microbiology Reports     Hybrid Journal   (Followers: 1)
Current Issues in Molecular Biology     Open Access   (Followers: 2)
Current Microbiology     Hybrid Journal   (Followers: 9)
Current Molecular Biology Reports     Hybrid Journal   (Followers: 1)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 25)
Current Tissue Engineering     Hybrid Journal   (Followers: 1)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 5)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 7)
Disease and Molecular Medicine     Open Access   (Followers: 1)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (Followers: 2)
Environmental Microbiology     Hybrid Journal   (Followers: 13)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 3)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 11)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 4)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 16)
European Journal of Microbiology and Immunology     Open Access   (Followers: 8)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 5)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 7)
Fems Microbiology Letters     Hybrid Journal   (Followers: 17)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 21)
Fermentation     Open Access  
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 13)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 2)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 3)
Frontiers in Cellular Neuroscience     Open Access   (Followers: 3)
Frontiers in Microbiology     Open Access   (Followers: 8)
Frontiers in Molecular Neuroscience     Open Access   (Followers: 1)
Future Microbiology     Full-text available via subscription   (Followers: 3)
Future Virology     Full-text available via subscription   (Followers: 7)
Gene Expression     Full-text available via subscription  
Genetica si Biologie Moleculara     Open Access  
Genetics and Molecular Research     Open Access   (Followers: 3)
Geomicrobiology Journal     Hybrid Journal   (Followers: 2)
Gut Microbes     Full-text available via subscription   (Followers: 7)
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: 3)
Inside the Cell     Open Access  
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 5)
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: 7)
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: 3)
International Journal of Virology and Molecular Biology     Open Access  
International Microbiology     Open Access   (Followers: 3)
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: 1)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 1)
Journal of Applied Microbiology     Hybrid Journal   (Followers: 10)
Journal of Bacteriology     Hybrid Journal   (Followers: 23)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 3)
Journal of Biomolecular Structure and Dynamics     Hybrid Journal   (Followers: 1)
Journal of Bionanoscience     Full-text available via subscription  
Journal of Brewing and Distilling     Open Access  
Journal of Cell and Animal Biology     Open Access  
Journal of Cell Biology and Genetics     Open Access   (Followers: 1)
Journal of Clinical Microbiology     Hybrid Journal   (Followers: 25)
Journal of Clinical Pathology     Full-text available via subscription   (Followers: 12)
Journal of Extracellular Vesicles     Open Access   (Followers: 3)
Journal of Food Microbiology     Open Access   (Followers: 1)
Journal of General and Molecular Virology     Open Access  
Journal of Genes and Cells     Open Access  
Journal of Global Antimicrobial Resistance     Hybrid Journal   (Followers: 1)
Journal of Histology     Open Access  
Journal of Industrial Microbiology and Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Medical Microbiology     Full-text available via subscription   (Followers: 3)
Journal of Metabonomics & Metabolites     Partially Free   (Followers: 1)
Journal of Microbiological Methods     Hybrid Journal   (Followers: 1)
Journal of Microbiology     Hybrid Journal   (Followers: 7)
Journal of Microbiology and Antimicrobials     Open Access   (Followers: 2)
Journal of Microbiology Research     Open Access   (Followers: 2)
Journal of Micropalaeontology     Hybrid Journal   (Followers: 6)
Journal of Molecular Biochemistry     Open Access   (Followers: 2)
Journal of Molecular Biology Research     Open Access   (Followers: 2)
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 12)
Journal of Molecular Pathophysiology     Open Access   (Followers: 1)
Journal of Molecular Psychiatry     Open Access   (Followers: 8)
Journal of Pharmacy & Bioresources     Full-text available via subscription   (Followers: 3)
Journal of Plant Molecular Biology and Biotechnology     Open Access   (Followers: 7)
Journal of Plant Pathology & Microbiology     Open Access  
Journal of Proteome Science and Computational Biology     Open Access  
Journal of Regenerative Medicine and Tissue Engineering     Open Access   (Followers: 1)
Journal of The Academy of Clinical Microbiologists     Open Access  
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 1)
Journal of the Institute of Brewing     Free  
Journal of Tropical Microbiology and Biotechnology     Full-text available via subscription  
Jundishapur Journal of Microbiology     Open Access  
Letters In Applied Microbiology     Hybrid Journal   (Followers: 5)
Macrophage     Open Access  
MAP Kinase     Open Access  
Medical Mycology     Open Access   (Followers: 3)
Methods in Molecular Biology     Hybrid Journal   (Followers: 17)
Microbes and Health     Open Access   (Followers: 1)
Microbes and Infection     Full-text available via subscription   (Followers: 4)
Microbial Biotechnology     Open Access   (Followers: 4)
Microbial Cell Factories     Open Access   (Followers: 7)
Microbial Drug Resistance     Hybrid Journal   (Followers: 4)
Microbial Ecology     Hybrid Journal   (Followers: 6)
Microbial Ecology in Health and Disease     Open Access  
Microbial Informatics and Experimentation     Open Access   (Followers: 1)
Microbial Pathogenesis     Hybrid Journal   (Followers: 6)
Microbiologia Medica     Open Access   (Followers: 1)
Microbiological Research     Hybrid Journal   (Followers: 6)
Microbiology     Hybrid Journal   (Followers: 12)
Microbiology (SGM)     Full-text available via subscription   (Followers: 16)
Microbiology and Immunology     Hybrid Journal   (Followers: 10)
Microbiology and Molecular Biology Reviews     Hybrid Journal   (Followers: 21)
Microbiology Australia     Hybrid Journal  
Microbiology Discovery     Open Access  
Microbiology Indonesia     Open Access  
Microbiology Research     Open Access   (Followers: 7)
MicrobiologyOpen     Open Access   (Followers: 2)
Microbiome     Hybrid Journal   (Followers: 2)
Microbiome Science and Medicine     Open Access  
Microorganisms     Open Access   (Followers: 2)
MicroRNA     Hybrid Journal   (Followers: 1)
Molecular and Cellular Therapies     Open Access  
Molecular Biology and Genetic Engineering     Open Access  
Molecular Biology Research Communications     Open Access   (Followers: 1)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 1)
Molecular Genetics, Microbiology and Virology     Hybrid Journal   (Followers: 5)
Molecular Imaging     Open Access  
Molecular Imaging and Biology     Hybrid Journal   (Followers: 2)
Molecular Medicine     Open Access   (Followers: 1)
Molecular Medicine Reports     Full-text available via subscription   (Followers: 5)
Molecular Microbiology     Hybrid Journal   (Followers: 25)
Molecular Oral Microbiology     Partially Free   (Followers: 3)
Molecular Systems Biology     Open Access   (Followers: 9)
Molecular Therapy - Methods & Clinical Development     Open Access  
mSphere     Open Access  

        1 2     

Journal Cover International Journal of Food Microbiology
  [SJR: 1.614]   [H-I: 121]   [12 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0168-1605
   Published by Elsevier Homepage  [2970 journals]
  • Multi-criteria framework as an innovative tradeoff approach to determine
           the shelf-life of high pressure-treated poultry
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): S. Guillou, M. Lerasle, H. Simonin, V. Anthoine, R. Chéret, M. Federighi, J.-M. Membré
      A multi-criteria framework combining safety, hygiene and sensorial quality was developed to investigate the possibility of extending the shelf-life and/or removing lactate by applying High Hydrostatic Pressure (HHP) in a ready-to-cook (RTC) poultry product. For this purpose, Salmonella and Listeria monocytogenes were considered as safety indicators and Escherichia coli as hygienic indicator. Predictive modeling was used to determine the influence of HHP and lactate concentration on microbial growth and survival of these indicators. To that end, probabilistic assessment exposure models developed in a previous study (Lerasle, M., Guillou, S., Simonin, H., Anthoine, V., Chéret, R., Federighi, M., Membré, J.M. 2014. Assessment of Salmonella and L. monocytogenes level in ready-to-cook poultry meat: Effect of various high pressure treatments and potassium lactate concentrations. International Journal of Food Microbiology 186, 74–83) were used for L. monocytogenes and Salmonella. Besides, for E. coli, an exposure assessment model was built by modeling data from challenge-test experiments. Finally, sensory tests and color measurements were performed to evaluate the effect of HHP on the organoleptic quality of an RTC product. Quantitative rules of decision based on safety, hygienic and organoleptic criteria were set. Hygienic and safety criteria were associated with probability to exceed maximum contamination levels of L. monocytogenes, Salmonella and E. coli at the end of the shelf-life whereas organoleptic criteria corresponded to absence of statistical difference between pressurized and unpressurized products. A tradeoff between safety and hygienic risk, color and taste, was then applied to define process and formulation enabling shelf-life extension. In the resulting operating window, one condition was experimentally assayed on naturally contaminated RTC products to validate the multi-criteria approach. As a conclusion, the framework was validated; it was possible to extend the shelf-life of an RTC poultry product containing 1.8% (w/w) lactate by one week, despite slight color alteration. This approach could be profitably implemented by food processors as a decision support tool for shelf-life determination.


      PubDate: 2016-06-24T07:35:18Z
       
  • Culture-independent bacterial community profiling of carbon dioxide
           treated raw milk
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Raquel Lo, Mark S. Turner, Mike Weeks, Nidhi Bansal
      Due to technical simplicity and strong inhibition against the growth of psychrotrophic bacteria in milk, CO2 treatment has emerged as an attractive processing aid to increase the storage time of raw milk before downstream processing. However, it is yet to be adopted by the industry. In order to further explore the suitability of CO2 treatment for raw milk processing, the bacterial populations of carbonated raw milk collected locally from five different sources in Australia were analysed with next-generation sequencing. Growth inhibition by CO2 was confirmed, with spoilage delayed by at least 7days compared with non-carbonated controls. All non-carbonated controls were spoiled by Gammaproteobacteria, namely Pseudomonas fluorescens group bacteria, Serratia and Erwinia. Two out of the five carbonated samples shared the same spoilage bacteria as their corresponding controls. The rest of the three carbonated samples were spoiled by the lactic acid bacterium (LAB) Leuconostoc. This is consistent with higher tolerance of LAB towards CO2 and selection of LAB in meat products stored in CO2-enriched modified atmosphere packaging. No harmful bacteria were found to be selected by CO2. LAB are generally regarded as safe (GRAS), thus the selection for Leuconostoc by CO2 in some of the samples poses no safety concern. In addition, we have confirmed previous findings that 454 pyrosequencing and Illumina sequencing of 16S rRNA gene amplicons from the same sample yield highly similar results. This supports comparison of results obtained with the two different sequencing platforms, which may be necessary considering the imminent discontinuation of 454 pyrosequencing.


      PubDate: 2016-06-24T07:35:18Z
       
  • Critical analysis of the maximum non inhibitory concentration (MNIC)
           method in quantifying sub-lethal injury in Saccharomyces cerevisiae cells
           exposed to either thermal or pulsed electric field treatments
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): V. Kethireddy, I. Oey, Tim Jowett, P. Bremer
      Sub-lethal injury within a microbial population, due to processing treatments or environmental stress, is often assessed as the difference in the number of cells recovered on non-selective media compared to numbers recovered on a “selective media” containing a predetermined maximum non-inhibitory concentration (MNIC) of a selective agent. However, as knowledge of cell metabolic response to injury, population diversity and dynamics increased, the rationale behind the conventional approach of quantifying sub-lethal injury must be scrutinized further. This study reassessed the methodology used to quantify sub-lethal injury for Saccharomyces cerevisiae cells (≈ 4.75 Log CFU/mL) exposed to either a mild thermal (45°C for 0, 10 and 20min) or a mild pulsed electric field treatment (field strengths of 8.0–9.0kV/cm and energy levels of 8, 14 and 21kJ/kg). Treated cells were plated onto either Yeast Malt agar (YM) or YM containing NaCl, as a selective agent at 5–15% in 1% increments. The impact of sub-lethal stress due to initial processing, the stress due to selective agents in the plating media, and the subsequent variation of inhibition following the treatments was assessed based on the CFU count (cell numbers). ANOVA and a generalised least squares model indicated significant effects of media, treatments, and their interaction effects (P <0.05) on cell numbers. It was shown that the concentration of the selective agent used dictated the extent of sub-lethal injury recorded owing to the interaction effects of the selective component (NaCl) in the recovery media. Our findings highlight a potential common misunderstanding on how culture conditions impact on sub-lethal injury. Interestingly for S. cerevisiae cells the number of cells recovered at different NaCl concentrations in the media appears to provide valuable information about the mode of injury, the comparative efficacy of different processing regimes and the inherent degree of resistance within a population. This approach may provide similar information for other micro-organisms.


      PubDate: 2016-06-24T07:35:18Z
       
  • Protein abundance changes of Zygosaccharomyces rouxii in different sugar
           concentrations
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Hong Guo, Chen Niu, Bin Liu, JianPing Wei, HuXuan Wang, YaHong Yuan, TianLi Yue
      Zygosaccharomyces rouxii is a yeast which can cause spoilage in the concentrated juice industries. It exhibits resistance to high sugar concentrations but genome- and proteome-wide studies on Z. rouxii in response to high sugar concentrations have been poorly investigated. Herein, by using a 2-D electrophoresis based workflow, the proteome of a wild strain of Z. rouxii under different sugar concentrations has been analyzed. Proteins were extracted, quantified, and subjected to 2-DE analysis in the pH range 4–7. Differences in growth (lag phase), protein content (13.97–19.23mg/g cell dry weight) and number of resolved spots (196–296) were found between sugar concentrations. ANOVA test showed that 168 spots were different, and 47 spots, corresponding to 40 unique gene products have been identified. These protein species are involved in carbohydrate and energy metabolism, amino acid metabolism, response to stimulus, protein transport and vesicle organization, cell morphogenesis regulation, transcription and translation, nucleotide metabolism, amino-sugar nucleotide-sugar pathways, oxidoreductases balancing, and ribosome biogenesis. The present study provides important information about how Z. rouxii acts to cope with high sugar concentration at molecular levels, which might enhance our global understanding of Z. rouxii's high sugar-tolerance trait.


      PubDate: 2016-06-20T07:33:00Z
       
  • Physical and antimicrobial properties of cinnamon bark oil
           co-nanoemulsified by lauric arginate and Tween 80
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Jonas Hilbig, Qiumin Ma, P. Michael Davidson, Jochen Weiss, Qixin Zhong
      Lauric arginate (LAE) is a water-soluble cationic surfactant which has antimicrobial activity against a broad spectrum of foodborne pathogens. Some spice essential oils are effective lipophilic antimicrobials. Combining both antimicrobials may reduce their usage levels and possible negative sensory impacts when applied in complex food matrices. The objective of this study was to combine a nonionic surfactant (Tween 80) with LAE to form stable nanoemulsions with cinnamon bark essential oil (CBO) and to characterize the antimicrobial activity of these nanoemulsions. CBO was homogenized at 1% w/w in the aqueous phase with 3% w/w Tween 80 and 0.05–0.375% w/w LAE, followed by heating at 90°C for 30min to obtain final emulsions. With 0.125% and higher LAE, transparent emulsions with ~100nm in hydrodynamic diameter were observed to be stable during 30-day storage at 21°C. Antimicrobial activities of the nanoemulsion prepared with Tween 80 and 0.375% w/w LAE were studied. The respective minimum inhibitory concentrations (MICs) of the nanoemulsion in tryptic soy broth (TSB) were 12, 7, and 8ppm LAE for Salmonella enteritidis, Escherichia coli O157:H7, and Listeria monocytogenes, while those of free LAE were 11, 6, and 6ppm, respectively. MICs of CBO were 400ppm for the tested bacteria and Tween 80 at 6% w/w did not show inhibitory effect. Growth kinetics of the bacteria in TSB treated with the nanoemulsion or individual components at concentrations corresponding to the MICs of free LAE showed that binding among the LAE and Tween 80 and CBO components resulted in the antibacterial activity of nanoemulsion being lower than same concentrations of free LAE and CBO. Conversely, little difference was observed for the individual antimicrobials and the nanoemulsion in 2% reduced fat milk, and 750ppm LAE and 2000ppm CBO were observed to be the dominant antimicrobial against Gram-positive and Gram-negative bacteria, respectively. The growth of L. monocytogenes in 2% reduced fat milk at 4°C was not observed when treated by the nanoemulsion corresponding to 187.5ppm LAE and 500ppm CBO. Therefore, stable and transparent nanoemulsions of EOs can be prepared with the combination of LAE and Tween 80 without compromising antimicrobial activities.


      PubDate: 2016-06-20T07:33:00Z
       
  • The environmental and intrinsic yeast diversity of Cuban cocoa bean heap
           fermentations
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Yurelkys Fernández Maura, Tom Balzarini, Pablo Clapé Borges, Pierre Evrard, Luc De Vuyst, H.-M. Daniel
      The environmental yeast diversity of spontaneous cocoa bean fermentations in east Cuba was investigated. Seven fermentations, 25 equipment- and handling-related samples, and 115 environmental samples, such as flowers, leaf and cocoa pod surfaces, as well as drosophilid insects, were analysed. The basic fermentation parameters temperature and pH were recorded during five fermentations for at least six days. A total of 435 yeast isolates were identified by a combination of PCR-fingerprinting of genomic DNA with the M13 primer and sequence analysis of DNA from representative isolates, using the internal transcribed spacer region, the D1/D2 region of the large subunit rRNA gene, and an actin gene-encoding fragment, as required. Among 65 yeast species detected, Pichia manshurica and Hanseniaspora opuntiae were the most frequently isolated species, obtained from five and four fermentations, followed in frequency by Pichia kudriavzevii from two fermentations. Saccharomyces cerevisiae was isolated only occasionally. Cocoa fermentation yeast species were also present on processing equipment. The repeated isolation of a preliminarily as Yamadazyma sp. classified species, a group of strains similar to Saccharomycopsis crataegensis from fermentations and equipment, and the isolation of fifteen other potentially novel yeast species in low numbers provides material for further studies. Environmental samples showed higher yeast diversity compared to the fermentations, included the most frequent fermentation species, whereas the most frequently isolated environmental species were Candida carpophila, Candida conglobata, and Candida quercitrusa. Potential selective advantages of the most frequently isolated species were only partly explained by the physiological traits tested. For instance, tolerance to higher ethanol concentrations was more frequent in strains of Pichia spp. and S. cerevisiae compared to Hanseniaspora spp.; the ability to also assimilate ethanol might have conferred a selective advantage to Pichia spp. In contrast, high glucose tolerance was common among strains of Hanseniaspora spp., Torulaspora delbrueckii, and Candida tropicalis, among which only Hanseniaspora spp. were frequently isolated.


      PubDate: 2016-06-20T07:33:00Z
       
  • Effect of the addition of phytosterols and tocopherols on Streptococcus
           thermophilus robustness during industrial manufacture and ripening of a
           functional cheese as evaluated by qPCR and RT-qPCR
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): J. Pega, S. Rizzo, C.D. Pérez, L. Rossetti, G. Díaz, S.M. Ruzal, M. Nanni, A.M. Descalzo
      The quality of functional food products designed for the prevention of degenerative diseases can be affected by the incorporation of bioactive compounds. In many types of cheese, the performance of starter microorganisms is critical for optimal elaboration and for providing potential probiotic benefits. Phytosterols are plant lipophilic triterpenes that have been used for the design of functional dairy products because of their ability to lower serum cholesterol levels in humans. However, their effect on the starter culture behavior during cheesemaking has not yet been studied. Here, we followed DNA and RNA kinetics of the bacterium Streptococcus thermophilus, an extensively used dairy starter with probiotic potential, during industrial production of a functional, semi-soft, reduced-fat cheese containing phytosterol esters and alpha-tocopherol as bioactive compounds. For this purpose, real-time quantitative PCR (qPCR) and reverse transcription-qPCR (RT-qPCR) assays were optimized and applied to samples obtained during the manufacture and ripening of functional and control cheeses. An experimental set-up was used to evaluate the detection threshold of free nucleic acids for extraction protocols based on pelleted microorganisms. To our knowledge, this straight-forward approach provides the first experimental evidence indicating that DNA is not a reliable marker of cell integrity, whereas RNA may constitute a more accurate molecular signature to estimate both bacterial viability and metabolic activity. Compositional analysis revealed that the bioactive molecules were effectively incorporated into the cheese matrix, at levels considered optimal to exert their biological action. The starter S. thermophilus was detected by qPCR and RT-qPCR during cheese production at the industrial level, from at least 30min after its inoculation until 81days of ripening, supporting the possible role of this species in shaping organoleptic profiles. We also showed for the first time that the addition of phytosterols at functional concentrations, not only did not affect starter performance but also correlated with a significant increase in target DNA and cDNA levels in most of the time points evaluated throughout cheesemaking. Therefore, these findings suggest that the growth and metabolism of S. thermophilus may be enhanced by the incorporation of these biologically active molecules during cheese production, providing important information for the industrial design of novel fermented foods.


      PubDate: 2016-06-16T03:57:05Z
       
  • Viability of murine norovirus in salads and dressings and its inactivation
           using heat-denatured lysozyme
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Hajime Takahashi, Tomoki Tsuchiya, Michiko Takahashi, Moemi Nakazawa, Tomoka Watanabe, Akira Takeuchi, Takashi Kuda, Bon Kimura
      In recent years, a number of food poisoning outbreaks due to the contamination of norovirus in ready-to-eat (RTE) foods such as salads have been reported, and this issue is regarded as a global problem. The risk of contamination of fresh vegetables with norovirus has been previously reported, but the survivability of norovirus that contaminates salads remains unknown. In addition, there have been limited reports on the control of norovirus in food products by using inactivating agents. In this study, the viability of norovirus in various types of salads and dressings was examined using murine norovirus strain 1 (MNV-1) as a surrogate for the closely related human norovirus. In addition, the inactivation of MNV-1 in salads was examined using heat-denatured lysozyme, which had been reported to inactivate norovirus. MNV-1 was inoculated in 4 types of salads (coleslaw, thousand island salad, vinaigrette salad, egg salad) and 3 types of dressings (mayonnaise, thousand island dressing, vinaigrette dressing), stored at 4°C for 5days. The results revealed that in the vinaigrette dressing, the infectivity of MNV-1 decreased by 2.6logPFU/mL in 5days, whereas in the other dressings and salads, the infectivity of MNV-1 did not show any significant decrease. Next, 1% heat-denatured lysozyme was added to the 4 types of salads, and subsequently it was found that in 2 types of salads (thousand island salad, vinaigrette salad), the infectivity of MNV-1 decreased by >4.0logPFU/g, whereas in coleslaw salad, a decrease of 3.0logPFU/g was shown. However, in egg salads, the infectivity of MNV-1 did not show such decrease. These results suggest that norovirus can survive for 5days in contaminated salads. Further, these findings also indicated that heat-denatured lysozyme had an inactivating effect on norovirus, even in salads. In the future, heat-denatured lysozyme can be used as a novel norovirus-inactivating agent, although it is essential to investigate the mechanism of inactivating effect of heat-denatured lysozyme against norovirus.


      PubDate: 2016-06-16T03:57:05Z
       
  • Can the development and autolysis of lactic acid bacteria influence the
           cheese volatile fraction' The case of Grana Padano
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Camilla Lazzi, Milena Povolo, Francesco Locci, Valentina Bernini, Erasmo Neviani, Monica Gatti
      In this study, the relationship between the dynamics of the growth and lysis of lactic acid bacteria in Grana Padano cheese and the formation of the volatile flavor compounds during cheese ripening was investigated. The microbial dynamics of Grana Padano cheeses that were produced in two different dairies were followed during ripening. The total and cultivable lactic microflora, community composition as determined by length heterogeneity-PCR (LH-PCR), and extent of bacterial lysis using an intracellular enzymatic activity assay were compared among cheeses after 2, 6 and 13months of ripening in two dairies. The evolution of whole and lysed microbiota was different between the two dairies. In dairy 2, the number of total cells was higher than that in dairy 1 in all samples, and the number of cells that lysed during ripening was lower. In addition, at the beginning of ripening (2months), the community structure of the cheese from dairy 2 was more complex and was composed of starter lactic acid bacteria (Lactobacillus helveticus and Lactobacillus delbrueckii) and NSLAB, possibly arising from raw milk, including Lactobacillus rhamnosus/Lactobacillus casei and Pediococcus acidilactici. On the other hand, the cheese from dairy 1 that ripened for 2months was mainly composed of the SLAB L. helveticus and L. delbrueckii. An evaluation of the free-DNA fraction through LH-PCR identified those species that had a high degree of lysis. Data on the dynamics of bacterial growth and lysis were evaluated with respect to the volatile profile and the organic acid content of the two cheeses after 13months of ripening, producing very different results. Cheese from dairy 1 showed a higher content of free fatty acids, particularly those deriving from milk fat lipolysis, benzaldehyde and organic acids, such as pGlu and citric. In contrast, cheese from dairy 2 had a greater amount of ketones, alcohols, hydrocarbons, acetic acid and propionic acid. Based on these results, we can conclude that in the first cheese, the intracellular enzymes that were released from lysis were mainly involved in aroma formation, whereas in the second cheese, the greater complexity of volatile compounds may be associated with its more complex microbial composition caused from SLAB lysis and NSLAB (mainly L. rhamnosus/L. casei) growth during ripening.


      PubDate: 2016-06-16T03:57:05Z
       
  • Aflatoxin B1 degradation by liquid cultures and lysates of three bacterial
           strains
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Oluwafemi Ayodeji Adebo, Patrick Berka Njobeh, Sibusiso Sidu, Matsobane Godfrey Tlou, Vuyo Mavumengwana
      Aflatoxin contamination remains a daunting issue to address in food safety. In spite of the efforts geared towards prevention and elimination of this toxin, it still persists in agricultural commodities. This has necessitated the search for other measures such as microbial degradation to combat this hazard. In this study, we investigated the biodegradation of aflatoxin B1 (AFB1), using lysates of three bacterial strains (Pseudomonas anguilliseptica VGF1, Pseudomonas fluorescens and Staphylococcus sp. VGF2) isolated from a gold mine aquifer. The bacterial cells were intermittently lysed in the presence and absence of protease inhibitors to obtain protease free lysates, subsequently incubated with AFB1 for 3, 6, 12, 24, and 48h to investigate whether any possible AFB1 degradation occurred using high performance liquid chromatography (HPLC) for detection. Results obtained revealed that after 6h of incubation, protease inhibited lysates of Staphylococcus sp. VGF2 demonstrated the highest degradation capacity of 100%, whereas P. anguilliseptica VGF1 and P. fluorescens lysates degraded AFB1 by 66.5 and 63%, respectively. After further incubation to 12h, no residual AFB1 was detected for all the lysates. Lower degrading ability was however observed for liquid cultures and uninhibited lysates. Data on cytotoxicity studies against human lymphocytes showed that the degraded products were less toxic than the parent AFB1. From this study, it can thus be deduced that the mechanism of degradation by these bacterial lysates is enzymatic. This study shows the efficacy of crude bacterial lysates for detoxifying AFB1 indicating potential for application in the food and feed industry.


      PubDate: 2016-06-16T03:57:05Z
       
  • Molecular characterization of alkaline protease of Bacillus
           amyloliquefaciens SP1 involved in biocontrol of Fusarium oxysporum
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Shiwani Guleria, Abhishek Walia, Anjali Chauhan, C.K. Shirkot
      An alkaline protease gene was amplified from genomic DNA of Bacillus amyloliquefaciens SP1 which was involved in effective biocontrol of Fusarium oxysporum. We investigated the antagonistic capacity of protease of B. amyloliquifaciens SP1, under in vitro conditions. The 5.62 fold purified enzyme with specific activity of 607.69U/mg reported 24.14% growth inhibition of F. oxysporum. However, no antagonistic activity was found after addition of protease inhibitor i.e. PMSF (15mM) to purified enzyme. An 1149bp nucleotide sequence of protease gene encoded 382 amino acids of 43kDa and calculated isoelectric point of 9.29. Analysis of deduced amino acid sequence revealed high homology (86%) with subtilisin E of Bacillus subtilis. The B. amyloliquefaciens SP1 protease gene was expressed in Escherichiax coli BL21. The expressed protease was secreted into culture medium by E. coli and exhibited optimum activity at pH8.0 and 60°C. The most reliable three dimensional structure of alkaline protease was determined using Phyre 2 server which was validated on the basis of Ramachandran plot and ERRAT value. The expression and structure prediction of the enzyme offers potential value for commercial application in agriculture and industry.


      PubDate: 2016-06-16T03:57:05Z
       
  • Improvement of the microbiological quality of ready-to-eat peeled shrimps
           (Penaeus vannamei) by the use of chitosan coatings
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Ximena Carrión-Granda, Idoya Fernández-Pan, Isabel Jaime, Jordi Rovira, Juan I. Maté
      Chitosan coatings incorporated with 0.5% of oregano and thyme EO were applied onto ready-to-eat peeled shrimp tails and packed under MAP conditions. The growth of naturally present spoilage microorganisms was evaluated for 12days during chilled storage (4°C). Coatings containing thyme EO were more effective in inhibiting the microbial species studied, specially lactic acid and psychrotrophic bacteria. As carrier of EOs, chitosan was more effective in inhibiting the growth of bacteria present in peeled shrimps than the direct application of an oil-water (O/W) emulsion. Finally, results from sensory analysis showed that the sensorial quality was affected by the chitosan-thyme coatings despite characteristics like firmness and colour were kept. The present work demonstrates the effectiveness of chitosan enriched coatings, offering a promising alternative to control the growth of spoilage and pathogen microorganisms on peeled shrimps during refrigeration storage.


      PubDate: 2016-06-16T03:57:05Z
       
  • Accessing spoilage features of osmotolerant yeasts identified from
           kiwifruit plantation and processing environment in Shaanxi, China
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Chen Niu, Yahong Yuan, Zhongqiu Hu, Zhouli Wang, Bin Liu, Huxuan Wang, Tianli Yue
      Osmotolerant yeasts originating from kiwifruit industrial chain can result in spoilage incidences, while little information is available about their species and spoilage features. This work identified possible spoilage osmotolerant yeasts from orchards and a manufacturer (quick-freeze kiwifruit manufacturer) in main producing areas in Shaanxi, China and further characterized their spoilage features. A total of 86 osmotolerant isolates dispersing over 29 species were identified through 26S rDNA sequencing at the D1/D2 domain, among which Hanseniaspora uvarum occurred most frequently and have intimate relationships with kiwifruit. RAPD analysis indicated a high variability of this species from sampling regions. The correlation of genotypes with origins was established except for isolates from Zhouzhi orchards, and the mobility of H. uvarum from orchard to the manufacturer can be speculated and contributed to spoilage sourcing. The manufacturing environment favored the inhabitance of osmotolerant yeasts more than the orchard by giving high positive sample ratio or osmotolerant yeast ratio. The growth curves under various glucose levels were fitted by Grofit R package and the obtained growth parameters indicated phenotypic diversity in the H. uvarum and the rest species. Wickerhamomyces anomalus (OM14) and Candida glabrata (OZ17) were the most glucose tolerant species and availability of high glucose would assist them to produce more gas. The test osmotolerant species were odor altering in kiwifruit concentrate juice. 3-Methyl-1-butanol, phenylethyl alcohol, phenylethyl acetate, 5-hydroxymethylfurfural (5-HMF) and ethyl acetate were the most altered compound identified by GC/MS in the juice. Particularly, W. anomalus produced 4-vinylguaiacol and M. guilliermondii produced 4-ethylguaiacol that would imperil product acceptance. The study determines the target spoilers as well as offering a detailed spoilage features, which will be instructive in implementing preventative measures to increase production safety of kiwifruit.


      PubDate: 2016-06-16T03:57:05Z
       
  • Multilocus analysis reveals large genetic diversity in Kluyveromyces
           marxianus strains isolated from Parmigiano Reggiano and Pecorino di
           Farindola cheeses
    • Abstract: Publication date: 16 September 2016
      Source:International Journal of Food Microbiology, Volume 233
      Author(s): Giuseppe Fasoli, Eladio Barrio, Rosanna Tofalo, Giovanna Suzzi, Carmela Belloch
      In the present study, we have analysed the genetic diversity in Kluyveromyces marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola cheesemaking environment. Molecular typing methods inter-RTL fingerprint and mtDNA RFLPs, as well as, sequence diversity and heterozygosity in the intergenic region between KmSSB1 and KmRIO2 genes and analysis of the mating locus were applied to 54 K. marxianus strains. Inter-RTL fingerprint revealed a large degree of genetic heterogeneity and clustering allowed differentiation of K. marxianus strains from different geographical origins. In general, inter-LTR profiles were more discriminating than RFLPs of mtDNA; however our results also indicate that both techniques could be complementary unveiling different degrees of genetic diversity. Sequence analysis of the intergenic region between KmSSB1 and KmRIO2 genes revealed 26 variable positions in which a double peak could be observed in the sequence chromatogram. Further analysis revealed the presence of heterozygous strains in the K. marxianus population isolated from Parmigiano Reggiano. On the other hand, all strains isolated from Pecorino di Farindola were homozygous. Two very different groups of haplotypes could be observed as well as mixtures between them. Phylogenetic reconstruction divided K. marxianus dairy strains into two separate populations. A few heterozygous strains in an intermediate position between them could also be observed. Mating type locus analysis revealed a large population of diploid strains containing both MATa and MATα alleles and few haploid strains, most of them presenting the MATα allele. Different scenarios explaining the presence and maintaining of homozygous and heterozygous diploids as well as hybrids between them in the Parmigiano Reggiano K. marxianus population are proposed. A principal component analysis supported the large differences between K. marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola.


      PubDate: 2016-06-16T03:57:05Z
       
  • Molecular epidemiology and risk factors for Anisakis simplex s.l.
           infection in blue whiting (Micromesistius poutassou) in a confluence zone
           of the Atlantic and Mediterranean: Differences between A. simplex s.s. and
           A. pegreffii.
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Magdalena Gómez-Mateos, Adela Valero, Manuel Morales-Yuste, Joaquina Martín-Sánchez
      Our study determined parameters of parasitization of Anisakis simplex s.l. in Micromesistius poutassou in a confluence zone of the Atlantic and Mediterranean, with a total prevalence of 82%. Also, in the three seasons analyzed, high prevalence's values were found, reaching 100% in spring; however mean intensity and abundance values were higher in winter. The use of molecular techniques to differentiate between Anisakis genotypes of the larvae characterized allowed obtaining values of 99.7% Anisakis simplex s.l. (50.1% A. simplex s.s., 42.9% A. pegreffii, 7.0% A. simplex s.s. - A. pegreffii hybrids) and 0.3% A. typica. The infections found in the fish were of both single and mixed species, in all the different possible combinations. The presence of A. simplex s.l. in the viscera varied according to genotype and season. Likewise, factors associated with the presence of the parasite in the ventral or dorsal musculature were different, where A. simplex s.s. proportion was double than that of A. pegreffii. The ecology of the two sibling species with regard to their location in fish and the influence of the season were different.


      PubDate: 2016-06-10T03:40:25Z
       
  • Editorial Board
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231




      PubDate: 2016-06-10T03:40:25Z
       
  • Effect of reuterin-producing Lactobacillus reuteri coupled with glycerol
           on the volatile fraction, odour and aroma of semi-hard ewe milk cheese
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Natalia Gómez-Torres, Marta Ávila, David Delgado, Sonia Garde
      The effect of the biopreservation system formed by Lactobacillus reuteri INIA P572, a reuterin-producing strain, and glycerol (required for reuterin production), on the volatile fraction, aroma and odour of industrial sized semi-hard ewe milk cheese (Castellano type) was investigated over a 3-month ripening period. The volatile compounds were extracted and analyzed by SPME-GC-MS and cheese odour and aroma profiles were studied by descriptive sensory analysis. Control cheese was made only with a mesophilic starter and experimental cheeses with L. reuteri were made with and without glycerol. The addition of L. reuteri INIA P572 to milk enhanced the formation of six volatile compounds. Despite the changes in the volatile compounds profile, the use of L. reuteri INIA P572 did not noticeably affect the sensory characteristics of cheese. On the other hand, the addition of L. reuteri INIA P572 coupled with 30mM glycerol enhanced the formation of twelve volatile compounds, but decreased the formation of five ones. The use of the biopreservation system did not affect overall odour and aroma quality of cheese although it resulted in a significant decrease of the odour intensity scores. In addition, this cheese received significant higher scores for “cheesy” aroma and significant lower scores for the aroma attributes “milky”, “caramel” and “yogurt-like”. The first two axes of a principal component analysis (PCA) performed for selected volatile compounds and sensory characteristics, accounting for 75% of the variability between cheeses, separated cheeses made with L. reuteri INIA P572 and glycerol from the rest of cheeses, and also differentiated control cheese from cheeses made with L. reuteri INIA P572 from day 60 onward. Our results showed that the reuterin-producing L. reuteri INIA P572 strain, when coupled with glycerol, may be a suitable biopreservation system to use in cheese without affecting odour and aroma quality.


      PubDate: 2016-06-10T03:40:25Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231




      PubDate: 2016-06-10T03:40:25Z
       
  • Identification of Lactobacillus brevis using a species-specific
           AFLP-derived marker
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Vincenzina Fusco, Grazia Marina Quero, Daniele Chieffi, Charles M.A.P. Franz
      A simple and specific method for the rapid detection and identification of Lactobacillus brevis was developed. A fAFLP (Fluorescent Amplified Fragment Length Polymorphisms) marker for L. brevis was used to design oligonucleotide primers for a species-specific PCR assay, targeting a 125bp fragment of the gene encoding the aldo/keto reductase of the diketogulonate-reductase family of L. brevis. This assay resulted in 100% inclusivity and exclusivity of assignment of strains to the species L. brevis. The analytical specificity of this assay was successfully tested to identify L. brevis isolates from sourdoughs.


      PubDate: 2016-06-10T03:40:25Z
       
  • Characterization of antimicrobial resistance in Klebsiella species
           isolated from chicken broilers
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Hao Wu, Mingyu Wang, Yuqing Liu, Xinhua Wang, Yunkun Wang, Jinxing Lu, Hai Xu
      The prevalence of antimicrobial resistant Klebsiella pneumoniae in poultry products has been a public concern, as it severely endangers food safety and human health. In this study, we investigated 90 antimicrobial resistant Klebsiella strains that were isolated from a commercial broiler slaughter plant in Shandong province of China. Nearly all (89/90) of the isolates were identified as infectious phylogenetic group KpI-type K. pneumoniae. Out of these 90 strains, 87 (96.7%) were multidrug-resistant isolates, and 87 (96.7%) were extended-spectrum beta-lactamase (ESBL)-producing isolates. An analysis of the prevalence of quinolone resistance genes showed that 7.8%, 77.8%, 26.7%, and 2.2% of the strains carried the qnrA, qnrB, qnrS, and qepA genes, respectively. An analysis of beta-lactam resistance genes showed that a high percentage of the strains contain the bla TEM (76.7%), bla SHV (88.9%), and bla CTX-M (75.6%) genes, among which three bla SHV subtypes (bla SHV-1, n =30; bla SHV-11, n =38; bla SHV-12, n =12) and three bla CTX-M subtypes (bla CTX-M-14, n =14; bla CTX-M-15, n =35; bla CTX-M-55, n =19) were found. A further investigation of mobile genetic elements involved in horizontal multidrug resistance gene transfer showed the presence of class 1 and 2 integrons in 77 (85.6%) and five (5.6%) isolates, respectively, while no class 3 integrons were detected. Four types of class 1 integrons containing specific gene cassette arrays (dfrA12–orfF–aadA2, dfrA17–aadA5, dfrA1–aadA1, and empty) were identified. Only one gene cassette array (dfrA1–sat2–aadA1) was detected in the class 2 integrons. Furthermore, four different types of insertion sequence common region 1 (ISCR1)-mediated downstream structures were successfully identified in 46 class 1 integron-positive isolates, among which ISCR1–sapA-like–qnrB2–qacEΔ1 was the most commonly observed structure. Chi-square tests revealed a significant association between ESBL genes, plasmid-mediated quinolone resistance (PMQR) genes, and class 1 integrons (p <0.01). Additional conjugation experiments confirmed this relationship (p <0.01) in transconjugants by finding that a high percentage of PMQR genes (74.0%) and class 1 integrons (73.7%) were co-transferred with ESBL genes. Finally, multilocus sequence typing (MLST) was performed, and it revealed that the isolates from chickens are widely distributed in humans, and that antimicrobial resistance is not only disseminated by clonal spreading, but largely by horizontal gene transfer. These results suggest that horizontal transfer of antimicrobial resistance genes by mobile genetic elements, such as integrons, plays a major role in the spread of antimicrobial resistance. Therefore, elucidating the structures of drug resistance integrons is of great importance to the commercial broiler slaughter plant in Shandong, China.


      PubDate: 2016-06-10T03:40:25Z
       
  • Editorial Board
    • Abstract: Publication date: 2 August 2016
      Source:International Journal of Food Microbiology, Volume 230




      PubDate: 2016-06-05T03:33:03Z
       
  • Isolation and characterization of Arcobacter spp. from fresh seafood and
           the aquatic environment
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Martina Laishram, Srinu Rathlavath, Manjusha Lekshmi, Sanath Kumar, Binaya Bhusan Nayak
      Arcobacter is an emerging pathogen associated with foods of animal origin. Members of the genus Arcobacter are increasingly being isolated from fish, shellfish and the aquatic environment. In the present study, we analyzed fish, shellfish and water samples for the presence of Arcobacter spp. by conventional isolation as well as by direct PCR on the enrichment broth. Of 100 samples comprising of 42 finfish, 34 shellfish and 24 water samples analyzed, Arcobacter spp. was isolated from 8 (19%) finfish, 5 (14.7%) shellfish and 5 (20.8%) water samples. Arcobacter DNA was detected in 24 (24%) samples by direct PCR on the enrichment broth. Based on m-PCR specific to different Arcobacter spp. and 16S rRNA sequence analyses, majority (19) of the isolates were identified as Arcobacter butzleri, while two isolates were Arcobacter mytili. All Arcobacter butzleri isolates harbored putative virulence genes cadF, ciaB, mviN, pldA, tlyA and cj1349. The two isolates of A. mytili harbored mviN and cj1349 genes only. The study highlights emerging problem of the contamination of aquatic environment and fresh seafood with potentially pathogenic Arcobacter spp.


      PubDate: 2016-06-05T03:33:03Z
       
  • Use of Schizosaccharomyces strains for wine fermentation—Effect on
           the wine composition and food safety
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): A.E. Mylona, J.M. Del Fresno, F. Palomero, I. Loira, M.A. Bañuelos, A. Morata, F. Calderón, S. Benito, J.A. Suárez-Lepe
      Schizosaccharomyces was initially considered as a spoilage yeast because of the production of undesirable metabolites such as acetic acid, hydrogen sulfide, or acetaldehyde, but it currently seems to be of great value in enology.o ced Nevertheless, Schizosaccharomyces can reduce all of the malic acid in must, leading to malolactic fermentation. Malolactic fermentation is a highly complicated process in enology and leads to a higher concentration of biogenic amines, so the use of Schizosaccharomyces pombe can be an excellent tool for assuring wine safety. Schizosaccharomyces also has much more potential than only reducing the malic acid content, such as increasing the level of pyruvic acid and thus the vinylphenolic pyranoanthocyanin content. Until now, few commercial strains have been available and little research on the selection of appropriate yeast strains with such potential has been conducted. In this study, selected and wild Sc. pombe strains were used along with a Saccharomyces cerevisiae strain to ferment red grape must. The results showed significant differences in several parameters including non-volatile and volatile compounds, anthocyanins, biogenic amines and sensory parameters.


      PubDate: 2016-06-05T03:33:03Z
       
  • Elucidation of enterotoxigenic Bacillus cereus outbreaks in Austria by
           complementary epidemiological and microbiological investigations, 2013
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Daniela Schmid, Corinna Rademacher, Elisabeth Eva Kanitz, Elrike Frenzel, Erica Simons, Franz Allerberger, Monika Ehling-Schulz
      Identifying Bacillus cereus as the causative agent of a foodborne outbreak still poses a challenge. We report on the epidemiological and microbiological investigation of three outbreaks of food poisoning (A, B, and C) in Austria in 2013. A total of 44% among 32 hotel guests (A), 22% among 63 employees (B) and 29% among 362 residents of a rehab clinic (C) fell sick immediately after meal consumption. B. cereus isolated from left overs or retained samples from related foods were characterized by toxin gene profiling, and molecular typing using panC sequencing and M13-PCR typing (in outbreak A and C). We identified two B. cereus strains in outbreak A, and six B. cereus strains, each in outbreak B and C; we also found Staphylococcus aureus and staphylococcal enterotoxins in outbreak A. The panC sequence based phylogenetic affiliation of the B. cereus strains, together with findings of the retrospective cohort analyses, helped determining their etiological role. Consumption of a mashed potatoes dish in outbreak A (RR: ∞), a pancake strips soup in outbreak B (RR 13.0; 95% CI 1.8–93.0) and for outbreak C of a fruit salad (RR 1.50; 95% CI 1.09–2.00), deer ragout (RR: 1.99; 95% CI 1.23–3.22) and a cranberry/pear (RR 2.46; 95% CI 1.50-4.03)were associated with increased risk of falling sick. An enterotoxigenic strain affiliated to the phylogenetic group with the highest risk of food poisoning was isolated from the crème spinach and the strawberry buttermilk, and also from the stool samples of the one B. cereus positive outbreak case-patient, who ate both. Our investigation of three food poisoning outbreaks illustrates the added value of a combined approach by using epidemiological, microbiological and genotyping methods in identifying the likely outbreak sources and the etiological B. cereus strains.


      PubDate: 2016-06-05T03:33:03Z
       
  • Bacterial quality and safety of packaged fresh leafy vegetables at the
           retail level in Finland
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): L.-L. Nousiainen, S. Joutsen, J. Lunden, M.-L. Hänninen, M. Fredriksson-Ahomaa
      Consumption of packaged fresh leafy vegetables, which are convenient ready-to-eat products, has increased during the last decade. The number of foodborne outbreaks associated with these products has concurrently increased. In our study, (1) label information, (2) O2/CO2 composition, (3) bacterial quality and (4) safety of 100 fresh leafy vegetables at the retail level were studied in Finland during 2013. Bacterial quality was studied using aerobic bacteria (AB) and coliform bacteria (CB) counts, and searching for the presence of Escherichia coli, Listeria and Yersinia. The safety was studied by the presence of Salmonella, ail-positive Yersinia, stx-positive E. coli (STEC) and Listeria monocytogenes using PCR and culturing. Important label information was unavailable on several packages originating from different companies. The packaging date was missing on all packages and the date of durability on 83% of the packages. Storage temperature was declared on 62% of the packages and 73% of the packages contained information about prewashing. The batch/lot number was missing on 29% of the packages. Very low oxygen (O2) (<1%) and elevated carbon dioxide (CO2) (2–22%) concentrations were measured in all packages labelled to contain a protective atmosphere. O2 and CO2 concentrations varied widely in the rest of the packages. AB and CB counts were high in the leafy vegetable samples varying between 6.2 and 10.6 and 4.2–8.3logcfu/g, respectively. In most of the samples, the AB and CB counts exceeded 108 and 106 cfu/g, respectively. A positive correlation was observed between the AB and CB counts. E. coli was isolated from 15% of the samples and Yersinia from 33%. L. monocytogenes was isolated from two samples and ail-positive Y. enterocolitica in one. Using PCR, STEC was detected in seven samples, and Salmonella and ail-positive Y. enterocolitica in two samples each. The AB and CB mean values of products originating from different companies varied widely. High AB and CB counts and pathogenic bacteria were detected in ready-to-eat products not needing washing before use. Our study shows that the bacterial quality and safety of packaged fresh leafy vegetables is poor and label information on the packages is inadequate. More studies are needed concerning the impact of a protective atmosphere on bacterial growth, and the impact of washing for removing bacteria.


      PubDate: 2016-06-05T03:33:03Z
       
  • Impact of the sampling method and chilling on the Salmonella recovery from
           pig carcasses
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Gerty Vanantwerpen, Lieven De Zutter, Dirk Berkvens, Kurt Houf
      Differences in recovery of Salmonella on pig carcasses using non-destructive and destructive sampling methods is not well understood in respect to the chilling processes applied in slaughterhouses. Therefore, in two slaughterhouses, four strains at two different concentrations were inoculated onto pork skin. Inoculated skin samples were sampled before and after chilling with two sampling methods: swabbing and destruction. Both slaughterhouses were visited three times and all tests were performed in triplicate. All samples were analysed using the ISO-method and recovered isolates were confirmed by PFGE. The chilling system (fast or conventional cooling) nor the sampling step (before and after chilling) did not significantly influence the recovery of Salmonella. However, swabbing after chilling leads to an underestimation of the real number of contaminated carcasses. Therefore, destructive sampling is the more designated sampling method after chilling.


      PubDate: 2016-05-31T08:09:37Z
       
  • Effects of different media on the enrichment of low numbers of Shiga
           toxin-producing Escherichia coli in mung bean sprouts and on the
           development of the sprout microbiome
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): H. Margot, T. Tasara, M.H. Zwietering, H. Joosten, R. Stephan
      Sprouted seeds have been implicated in a number of serious outbreaks caused by Salmonella and Shiga toxin-producing Escherichia coli. Sprouts pose a very complex challenge to bacterial pathogen enrichment and detection since they naturally contain high levels of background microflora including members of the Enterobacteriaceae. As such, the currently used method cannot ensure reliable detection of STEC in sprouts. In this study, we compared different media for the enrichment of Enterobacteriaceae in their ability to promote the growth of stressed STEC at 37°C and 42°C. Mung bean sprouts were spiked with low levels of STEC and their growth was recorded over time. In addition, the microbiome of mung bean sprouts was analysed before and after enrichment. Our results indicate that the growth of dry-stressed STEC is comparable in all of the tested enrichment media except for mTSB+Novobiocin and not influenced by the incubation temperature. Low levels of STEC spiked into the sprouts resuspended in media only grew to levels of around 4logcfu/ml during enrichment, which could reduce the probability of detection. Proteobacteria was the dominant phylum detected within the microbiome of non-enriched mung bean sprouts. During enrichment in EE-broth, Proteobacteria remained the most abundant phylum. In contrast, during enrichment in BPW the relative abundance of Proteobacteria decreased whereas Firmicutes increased when compared to the non-enriched mung bean sprout microbiome. The microbiome composition was not significantly influenced by the incubation temperature during enrichment in both BPW and EE-broth. This is the first study to examine the microbiome on sprouted mung bean seeds during BPW and EE enrichment and relates the bacterial community composition changes to the enrichment of pathogens.


      PubDate: 2016-05-31T08:09:37Z
       
  • Evolution of sourdough microbiota in spontaneous sourdoughs started with
           different plant materials
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Valery Ripari, Michael G. Gänzle, Enrico Berardi
      The preparation of sourdough in bakeries may include the use of inocula, e.g. fruits, flowers or rumen cuts to accelerate the process of selection of suitable microorganisms. The aim of this work was to investigate the effect of these inocula on the microbial evolution in sourdoughs. First, the microbiota of nineteen traditional sourdoughs that were initially started with diverse inocula was identified. Second, de novo sourdoughs were started with plant materials and the evolution of sourdough microbiota was investigated by culture, and by high-resolution melting curve quantitative PCR (HRM-qPCR). This study developed a new protocol for HRM-qPCR analysis of yeast microbiota in sourdough, and indicates this independent culture method suitable for characterization of yeasts. Microbiota of traditional sourdoughs were largely independent from the use of inoculum, however, Acetobacter spp. were identified only in sourdoughs started with apple flowers or apple pulp. In de novo sourdoughs started with plant materials, microbiota rapidly stabilized, and were characterized by Lactobacillus sanfranciscensis, Lactobacillus plantarum, Lactobacillus graminis, or Lactobacillus rossiae, and Saccharomyces cerevisiae as dominant species. Competition experiments revealed that the ecological fitness of L. plantarum, L. graminis, and L. rossiae in wheat or rye malt sourdoughs was lower when compared to L. sanfranciscensis, demonstrating that their presence in de novo sourdoughs reflects dispersal limitation. In conclusion, establishment of microbiota in de novo sourdoughs is dispersal limited. This study provides scientific support for the artisanal practice to inoculate de novo sourdoughs with flowers, berries, or related plant material.


      PubDate: 2016-05-31T08:09:37Z
       
  • Microbial safety and overall quality of cantaloupe fresh-cut pieces
           prepared from whole fruit after wet steam treatment
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Dike O. Ukuku, David J. Geveke, Lee Chau, Brendan A. Niemira
      Fresh-cut cantaloupes have been associated with outbreaks of Salmonellosis. Minimally processed fresh-cut fruits have a limited shelf life because of deterioration caused by spoilage microflora and physiological processes. The objectives of this study were to use a wet steam process to 1) reduce indigenous spoilage microflora and inoculated populations of Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes on the surface of cantaloupes, and 2) reduce the populations counts in cantaloupe fresh-cut pieces after rind removal and cutting. The average inocula of Salmonella, E. coli O157:H7 and Listeria monocytogenes was 107 CFU/ml and the populations recovered on the cantaloupe rind surfaces after inoculation averaged 4.5, 4.8 and 4.1logCFU/cm2, respectively. Whole cantaloupes were treated with a wet steam processing unit for 180s, and the treated melons were stored at 5°C for 29days. Bacterial populations in fresh-cut pieces prepared from treated and control samples stored at 5 and 10°C for up to 12days were determined and changes in color (CIE L*, a*, and b*) due to treatments were measured during storage. Presence and growth of aerobic mesophilic bacteria and Salmonella, E. coli O157:H7 and L. monocytogenes were determined in fresh-cut cantaloupe samples. There were no visual signs of physical damage on all treated cantaloupe surfaces immediately after treatments and during storage. All fresh-cut pieces from treated cantaloupes rind surfaces were negative for bacterial pathogens even after an enrichment process. Steam treatment significantly (p<0.05) changed the color of the fresh-cut pieces. Minimal wet steam treatment of cantaloupes rind surfaces designated for fresh-cut preparation will enhance the microbial safety of fresh-cut pieces, by reducing total bacterial populations. This process holds the potential to significantly reduce the incidence of foodborne illness associated with fresh-cut fruits.


      PubDate: 2016-05-31T08:09:37Z
       
  • Shiga toxin-producing Escherichia coli strains isolated from dairy
           products — Genetic diversity and virulence gene profiles
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): T. Douëllou, S. Delannoy, S. Ganet, P. Mariani-Kurkdjian, P. Fach, E. Loukiadis, Mc. Montel, D. Thevenot-Sergentet
      Shiga toxin-producing Escherichia coli (STEC) are widely recognized as pathogens causing food borne disease. Here we evaluate the genetic diversity of 197 strains, mainly STEC, from serotypes O157:H7, O26:H11, O103:H2, O111:H8 and O145:28 and compared strains recovered in dairy products against strains from human, meat and environment cases. For this purpose, we characterized a set of reference-collection STEC isolates from dairy products by PFGE DNA fingerprinting and a subset of these by virulence-gene profiling. PFGE profiles of restricted STEC total DNA showed high genomic variability (0.9976 on Simpson's discriminatory index), enabling all dairy isolates to be differentiated. High-throughput real-time PCR screening of STEC virulence genes were applied on the O157:H7 and O26:H11 STEC isolates from dairy products and human cases. The virulence gene profiles of dairy and human STEC strains were similar. Nevertheless, frequency-wise, stx1 was more prevalent among dairy O26:H11 isolates than in human cases ones (87% vs. 44%) while stx2 was more prevalent among O26:H11 human isolates (23% vs. 81%). For O157:H7 isolates, stx1 (0% vs. 39%), nleF (40% vs 94%) and Z6065 (40% vs 100%) were more prevalent among human than dairy strains. Our data point to differences between human and dairy strains but these differences were not sufficient to associate PFGE and virulence gene profiles to a putative lower pathogenicity of dairy strains based on their lower incidence in disease. Further comparison of whole-genome expression and virulence gene profiles should be investigated in cheese and intestinal tract samples.


      PubDate: 2016-05-31T08:09:37Z
       
  • Inactivation of human norovirus and Tulane virus in simple media and fresh
           whole strawberries by ionizing radiation
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Erin DiCaprio, Nuttapong Phantkankum, Doug Culbertson, Yuanmei Ma, John H. Hughes, David Kingsley, Roberto M. Uribe, Jianrong Li
      Human norovirus (NoV) is a major cause of fresh produce-associated outbreaks and human NoV in irrigation water can potentially lead to viral internalization in fresh produce. Therefore, there is a need to develop novel intervention strategies to target internalized viral pathogens while maintaining fresh produce quality. In this study electron beam (E-beam) and gamma radiation were evaluated for efficacy against a human NoV GII.4 strain and Tulane virus (TV). Virus survival following ionizing radiation treatments was determined using direct quantitative reverse transcriptase PCR (RT-qPCR), the porcine gastric mucin magnetic bead (PGM-MB) binding assay followed by RT-qPCR, and plaque assay. In simple media, a high dose of E-beam treatment was required to completely abolish the receptor binding ability of human NoV (35.3kGy) and TV (19.5–24.1kGy), as assessed using the PGM-MB binding assay. Both human NoV and TV were more susceptible to gamma irradiation than E-beam, requiring 22.4kGy to achieve complete inactivation. In whole strawberries, no human NoV or TV RNA was detected following 28.7kGy of E-beam treatment using the PGM-MB binding assay. Overall, human NoV and TV are highly resistant to ionizing radiation and therefore the technology may not be suitable to eliminate viruses in fresh produce at the currently approved levels. In addition, the PGM-MB binding assay is an improved method to detect viral infectivity compared to direct RT-qPCR.


      PubDate: 2016-05-31T08:09:37Z
       
  • New insight into microbial diversity and functions in traditional
           Vietnamese alcoholic fermentation
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Vu Nguyen Thanh, Nguyen Thanh Thuy, Nguyen Thuy Chi, Dinh Duc Hien, Bui Thi Viet Ha, Dao Thi Luong, Pham Duc Ngoc, Pham Van Ty
      The roles of microorganisms in traditional alcoholic fermentation are often assumed based on abundance in the starter and activity in pure culture. There is a serious lack of hard evidence on the behavior and activity of individual microbial species during the actual fermentation process. In this study, microbial succession and metabolite changes during 7days of traditional Vietnamese alcoholic fermentation were monitored. Special attention was devoted to starch degradation. In total, 22 microbial species, including 6 species of filamentous fungi (Rhizopus microsporus, Rhizopus arrhizus, Mucor indicus, Mucor circinelloides, Cunninghamella elegans, Aspergillus niger), 1 yeast-like fungus (Saccharomycopsis fibuligera), 7 yeasts (Saccharomyces cerevisiae, Clavispora lusitaniae, Wickerhamomyces anomalus, Lindnera fabianii, Pichia kudriavzevii, Candida rugosa, Candida tropicalis), and 8 bacteria (Stenotrophomonas maltophilia, Lactobacillus brevis, Lactobacillus helveticus, Acinetobacter baumannii, Staphylococcus hominis, Bacillus megaterium, Enterobacter asburiae, Pediococcus pentosaceus) were identified. Despite the presence of a complex microbiota in the starter, the fermentation process is consistent and involves a limited number of functional species. Rapid change in microbial composition of fermentation mash was observed and it was correlated with ethanol content. Microbial biomass reached maximum during first 2days of solid state fermentation. Acidification of the medium took place in day 1, starch degradation in days 2, 3, 4, and alcohol accumulation from day 3. Although Sm. fibuligera dominated by cell count amongst potential starch degraders, zymography indicated that it did not produce amylase in the fermentation mash. In mixed culture with Rhizopus, amylase production by Sm. fibuligera is regulated by the moisture content of the substrate. Rhizopus was identified as the main starch degrader and S. cerevisiae as the main ethanol producer. Bacterial load was high but unstable in species composition and dominated by acid producers. M. indicus, Sm. fibuligera, W. anomalus and bacteria were regarded as satellite microorganisms. Their possible influence on organoleptic quality of fermentation product was discussed.


      PubDate: 2016-05-31T08:09:37Z
       
  • Bifidobacterial inulin-type fructan degradation capacity determines
           cross-feeding interactions between bifidobacteria and Faecalibacterium
           prausnitzii
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Frédéric Moens, Stefan Weckx, Luc De Vuyst
      Prebiotic inulin-type fructans (ITF) display a bifidogenic and butyrogenic effect. Four bifidobacterial strains (Bifidobacterium breve Yakult, Bifidobacterium adolescentis LMG 10734, Bifidobacterium angulatum LMG 11039T, and Bifidobacterium longum subsp. longum LMG 11047), displaying different ITF degradation capacities, were each grown in cocultivation with Faecalibacterium prausnitzii DSM 17677T, an ITF-degrading butyrate-producing colon bacterium, as to unravel their cross-feeding interactions. These coculture fermentations were performed in a medium for colon bacteria, whether or not including acetate (necessary for the growth of F. prausnitzii DSM 17677T and whether or not provided through cross-feeding), supplemented with oligofructose or inulin as the sole energy source. Bifidobacterium breve Yakult did not degrade oligofructose, resulting in the production of high concentrations of butyrate by F. prausnitzii DSM 17677T through oligofructose degradation. The degradation of oligofructose by B. adolescentis LMG 10734 and of oligofructose and inulin by B. angulatum LMG 11039T and B. longum LMG 11047 resulted in the production of acetate, which was cross-fed to F. prausnitzii DSM 17677T, enabling the latter strain to degrade oligofructose and inulin. Slow preferential degradation of the short chain length fractions of oligofructose (intracellularly) by B. adolescentis LMG 10734 enabled substantial oligofructose degradation by F. prausnitzii DSM 17677T. However, fast non-preferential degradation of all chain length fractions of oligofructose (extracellularly) and efficient degradation of the short chain length fractions of inulin by B. angulatum LMG 11039T and B. longum LMG 11047 made it impossible for F. prausnitzii DSM 17677T to compete for the available substrate. These results indicate that cross-feeding interactions between bifidobacteria and acetate-depending, butyrate-producing colon bacteria can be either a pure commensal or beneficial relationship between these bacteria, or can be dominated by competition, depending on the ITF degradation capacities of the bifidobacterial strains involved.


      PubDate: 2016-05-25T18:26:36Z
       
  • High prevalence of extended-spectrum and plasmidic AmpC
           beta-lactamase-producing Escherichia coli from poultry in Tunisia
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Elaa Maamar, Samia Hammami, Carla Andrea Alonso, Nouha Dakhli, Mohamed Salah Abbassi, Sana Ferjani, Zaineb Hamzaoui, Mabrouka Saidani, Carmen Torres, Ilhem Boutiba-Ben Boubaker
      This study was conducted to detect extended spectrum beta-lactamases (ESBLs) and plasmidic AmpC beta-lactamase (pAmpC-BL)-producing Escherichia coli isolates in industrial poultry samples were collected from healthy chickens of the three farms. Samples were inoculated onto desoxycholate-lactose-agar plates supplemented with cefotaxime (2mg/L). E. coli was identified by biochemical and molecular methods and antibiotic susceptibility testing by the disk diffusion method. Genes encoding ESBLs and pAmpC-BL were detected by PCR and sequencing. Phylogenetic groups were determined by triplex PCR. The molecular typing of strains was done by pulsed field gel electrophoresis (PFGE) and Multilocus Sequence Typing (MLST) in those isolates showing different PFGE patterns. Cefotaxime-resistant E. coli isolates were recovered in 48 of 137 fecal samples (35%), and one isolate/sample was further studied. The following beta-lactamase genes were detected: bla CTX-M-1 (29 isolates, isolated in all three farms), bla CTX-M-15 (5 isolates, confined in farm II), bla CTX-M-14 and bla CMY-2 (one isolate and 13 isolates, respectively, in farm III). The 48 cefotaxime-resistant isolates were distributed into phylogroups: B1 (n=21), A (n=15) and D (n=12). PFGE analysis revealed 19 unrelated patterns: 15 different profiles among ESBL-positive strains and 4 among the CMY-2-positive isolates. The following sequence types-associated phylogroups were detected: a) CTX-M-1-positive strains: lineages ST542-B1, ST212-B1, ST58-B1, ST155-B1 and ST349-D; b) CTX-M-15-positive strain: lineage ST405-D; c) CTX-M-14-positive strain: lineage ST1056-B1; d) CMY-2-positive strains: lineages ST117-D, ST2197-A, and ST155-B1. Healthy chickens constitute an important reservoir of ESBL- and pAmpC-BL-producing E. coli isolates that potentially could be transmitted to humans via the food chain or by direct contact.


      PubDate: 2016-05-25T18:26:36Z
       
  • Putrescine production by Lactococcus lactis subsp. cremoris CECT 8666 is
           reduced by NaCl via a decrease in bacterial growth and the repression of
           the genes involved in putrescine production
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Beatriz del Rio, Begoña Redruello, Victor Ladero, Maria Fernandez, Maria Cruz Martin, Miguel A. Alvarez
      The reduction of NaCl in food is a public health priority; high NaCl intakes have been associated with serious health problems. However, it is reported that reducing the NaCl content of cheeses may lead to an increase in the content of biogenic amines (BAs). The present work examines the effect of NaCl on the accumulation of putrescine (one of the BAs often detected at high concentration in cheese) in experimental Cabrales-like cheeses containing Lactococcus lactis subsp. cremoris CECT 8666, a dairy strain that catabolises agmatine to putrescine via the agmatine deiminase (AGDI) pathway. The genes responsible for this pathway are grouped in the AGDI cluster. This comprises a regulatory gene (aguR) (transcribed independently), followed by the catabolic genes that together form an operon (aguBDAC). Reducing the NaCl concentration of the cheese led to increased putrescine accumulation. In contrast, increasing the NaCl concentration of both pH-uncontrolled and pH-controlled (pH 6) cultures of L. lactis subsp. cremoris CECT 8666 significantly inhibited its growth and the production of putrescine. Such production appeared to be inhibited via a reduction in the transcription of the aguBDAC operon; no effect on the transcription of aguR was recorded. The present results suggest that low-sodium cheeses are at risk of accumulating higher concentrations of putrescine.


      PubDate: 2016-05-25T18:26:36Z
       
  • Prevalence and characteristics of verotoxigenic Escherichia coli strains
           isolated from pigs and pork products in Umbria and Marche regions of Italy
           
    • Abstract: Publication date: 2 September 2016
      Source:International Journal of Food Microbiology, Volume 232
      Author(s): Laura Ercoli, Silvana Farneti, Alessia Zicavo, Guerriero Mencaroni, Giuliana Blasi, Gianluca Striano, Stefania Scuota
      In total 1095 samples from 675 pork products, 210 swine colon contents, and 210 swine carcass sponge swabs were collected in Umbria and Marche regions of Italy and examined for the presence of Shiga toxin-producing Escherichia coli (STEC), also known as Verotoxin-producing E. coli (VTEC). After an enrichment step, each sample was analysed by real-time PCR to detect the stx1, stx2, and eae genes. stx-Positive samples were further tested for the “top five” serogroup markers (O157, O26, O103, O111, O145) and cultured onto selective media. The isolates were assigned to stx subtypes and tested for the presence of aaiC and aggR genes. Out of 420 swine samples, 38.6% faecal samples and 13.8% carcass sponge swabs were stx-positive. In total, 33 E. coli STEC isolates were obtained from 30 samples (4 carcasses and 26 colon contents) indicating a culture-positive rate of 7.1%. A higher culture-positive rate was observed in faecal samples (12.4%) than in carcass sponge swabs (1.9%). Out of 675 pork samples, 19 (2.8%) were stx-positive. No STEC strains were isolated from stx-positive pork products. We concluded that STEC isolation from foodstuffs remains difficult, despite the application of ISO/TS 13136:2012. Furthermore, in accordance with the results of studies conducted in other countries, we observed that most of swine STEC strains carried stx 2e gene and lacked of virulence genes, such as eae, aaiC and aggR, indicative of potential pathogenic characteristics for humans. Although the majority of STEC isolates did not express virulence factors correlating with severe human diseases, the association between swine STEC strains and human illness requires further investigations.


      PubDate: 2016-05-25T18:26:36Z
       
  • Non-aflatoxigenic Aspergillus flavus as potential biocontrol agents to
           
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): María Silvina Alaniz Zanon, Germán Gustavo Barros, Sofía Noemí Chulze
      Biological control is one of the most promising strategies for preventing aflatoxin contamination in peanuts at field stage. A population of 46 native Aspergillus flavus nonaflatoxin producers were analysed based on phenotypic, physiological and genetic characteristics. Thirty-three isolates were characterized as L strain morphotype, 3 isolates as S strain morphotype, and 10 isolates did not produce sclerotia. Only 11 of 46 non-aflatoxigenic isolates did not produce cyclopiazonic acid. The vegetative compatibility group (VCG) diversity index for the population was 0.37. For field trials we selected the non-aflatoxigenic A. flavus AR27, AR100G and AFCHG2 strains. The efficacy of single and mixed inocula as potential biocontrol agents in Northern Argentina was evaluated through a 2-year study (2014–2015). During the 2014 peanut growing season, most of the treatments reduced the incidence of aflatoxigenic strains in both soil and peanut kernel samples, and no aflatoxin was detected in kernels. During the 2015 growing season, there was a reduction of aflatoxigenic strains in kernel samples from the plots treated with the potential biocontrol agents. Reductions of aflatoxin contamination between 78.36% and 89.55% were observed in treated plots in comparison with the un-inoculated control plots. This study provides the first data on aflatoxin biocontrol based on competitive exclusion in the peanut growing region of Northern Argentina, and proposes bioproducts with potential use as biocontrol agents.


      PubDate: 2016-05-25T18:26:36Z
       
  • Effect of acidic electrolyzed water-induced bacterial inhibition and
           
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Hamzah M. Al-Qadiri, Murad A. Al-Holy, Setareh Ghorban Shiroodi, Mahmoudreza Ovissipour, Byju N. Govindan, Nivin Al-Alami, Shyam S. Sablani, Barbara Rasco
      The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hydrophila, Vibrio parahaemolyticus and Campylobacter jejuni in laboratory contaminated live clam (Venerupis philippinarum) and mussel (Mytilus edulis) was investigated. The initial levels of bacterial contamination were: in clam 4.9 to 5.7log10 CFU/g, and in mussel 5.1 to 5.5log10 CFU/g. Two types of AEW were used for treatment time intervals of 1 and 2h: strong (SAEW) with an available chlorine concentration (ACC) of 20mg/L, pH=3.1, and an oxidation-reduction potential (ORP) of 1150mV, and weak (WAEW) at ACC of 10mg/L, pH=3.55 and ORP of 950mV. SAEW and WAEW exhibited significant inhibitory activity against inoculated bacteria in both shellfish species with significant differences compared to saline solutions treatments (1–2% NaCl) and untreated controls (0h). SAEW showed the largest inhibitory activity, the extent of reduction (log10 CFU/g) ranged from 1.4–1.7 for E. coli O104:H4; 1.0–1.6 for L. monocytogenes; 1.3–1.6 for A. hydrophila; 1.0–1.5 for V. parahaemolyticus; and 1.5–2.2 for C. jejuni in both types of shellfish. In comparison, significantly (P <0.05) lower inhibitory effect of WAEW was achieved compared to SAEW, where the extent of reduction (log10 CFU/g) ranged from 0.7–1.1 for E. coli O104:H4; 0.6–0.9 for L. monocytogenes; 0.6–1.3 for A. hydrophila; 0.7–1.3 for V. parahaemolyticus; and 0.8–1.9 for C. jejuni in both types of shellfish. Among all bacterial strains examined in this study, AEW induced less bacterial injury (~0.1–1.0log10 CFU/g) and more inactivation effect. This study revealed that AEW (10–20mg/L ACC) could be used to reduce bacterial contamination in live clam and mussel, which may help control possible unhygienic practices during production and processing of shellfish without apparent changes in the quality of the shellfish.


      PubDate: 2016-05-20T18:21:08Z
       
  • A rapid and highly specific immunofluorescence method to detect
           Escherichia coli O157:H7 in infected meat samples
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Baskar Balakrishnan, Syed Barizuddin, Tumen Wuliji, Majed El-Dweik
      Developing rapid and sensitive methods for the detection of pathogenic Escherichia coli O157:H7 remains a major challenge in food safety. The present study attempts to develop an immunofluorescence technique that uses Protein-A-coated, magnetic beads as the platform. The immunofluorescence technique described here is a direct detection method in which E. coli O157:H7 cells are labeled with tetramethylrhodamine (TRITC) fluorescent dye. TRITC-labeled bacteria are captured by the desired antibody (Ab), which is immobilized on the Protein-A magnetic beads. Fluorescence of the captured cells is recorded in a fluorescence spectrophotometer, where the fluorescence values are shown to be directly proportional to the number of bacteria captured on the immunobead. The formation of an immunocomplex is evidenced by the fluorescence of the beads under microscopy. The Ab immobilization procedure is also evidenced by microscopy using fluorescein isothiocyanate (FITC)-labeled Ab. The total experimental time, including preparation of the sample, is just 1h. The minimum bacterial concentration detected by this method is 1.2±0.06×103 CFUml−1. The high specificity of this method was proved by using the specific monoclonal Ab (MAb) in the test. The proposed protocol was successfully validated with E. coli O157:H7-infected meat samples. This approach also opens the door for the detection of other bacterial pathogens using Protein-A magnetic beads as a detection platform.


      PubDate: 2016-05-20T18:21:08Z
       
  • Evaluation of the risk of fungal spoilage when substituting sucrose with
           commercial purified Stevia glycosides in sweetened bakery products
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Alicia Rodríguez, Naresh Magan, Angel Medina
      The objectives of this study were to compare the effect of different Stevia-based sugar substitutes (S1–S3), sucrose alone and a mixture of sucrose+S1 on: (a) humectant properties, (b) relative colonisation rates of sponge cake slices at 0.90 aw by strains of Aspergillus flavus, Eurotium amstelodami, Fusarium graminearum and Penicillium verrucosum at 20 and 25°C and (c) shelf-life periods in days prior to visible growth. Results showed that sucrose, S1 commercial sugar substitute and the mixture of sucrose+S1 in water solutions were able to reach water activity levels similar to those of glycerol and glucose mixtures. The S2 and S3 commercial sugar substitutes were unable to reduce aw levels significantly. At 25°C, colonisation of sponge cake slices by E. amstelodami, A. flavus and P. verrucosum occurred in all the treatments. Growth of F. graminearum only occurred on sponge cake slices containing S2 and S3 Stevia-based products at both temperatures. The best control of growth (30days) was achieved in cake slices modified with sucrose or S1 Stevia treatments inoculated with A. flavus and in the sucrose treatment for E. amstelodami at 20°C. F. graminearum growth was completely inhibited when sucrose alone, S1 or sucrose+S1 treatments were used at both temperatures. This study suggests that, as part of a hurdle technology approach, replacing sucrose with low calorie sugar substitutes based on Stevia glycosides needs to be done with care. This is because different products may have variable humectant properties and bulking agents which may shorten the potential shelf-life of intermediate moisture bakery products.


      PubDate: 2016-05-15T23:37:35Z
       
  • Penicillium salamii strain ITEM 15302: A new promising fungal starter for
           salami production
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): D. Magistà, M. Ferrara, M.A. Del Nobile, D. Gammariello, A. Conte, G. Perrone
      Traditional sausages are often considered of superior quality to sausages inoculated with commercial starter cultures and this is partially due to the action of the typical house microflora. Penicillium nalgiovense is the species commonly used as starter culture for dry-cured meat production. Recently a new species, Penicillium salamii, was described as typical colonizer during salami seasoning. In order to understand its contribution to the seasoning process, two different experiments on curing of fresh pork sausages were conducted using P. salamii ITEM 15302 in comparison with P. nalgiovense ITEM 15292 at small and industrial scale, and the dry-cured sausages were subjected to sensory analyses. Additionally, proteolytic and lipolytic in vitro assays were performed on both strains. P. salamii ITEM 15302 proved to be a fast growing mould on dry-cured sausage casings, well adapted to the seasoning process, with high lipolytic and proteolytic enzymatic activity that confers typical sensory characteristics to meat products. Therefore, P. salamii ITEM 15302 was shown to be a good candidate as new starter for meat industry.


      PubDate: 2016-05-15T23:37:35Z
       
  • Prevalence and characterization of plasmid-mediated quinolone resistance
           genes in Aeromonas spp. isolated from South African freshwater fish
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Hafizah Yousuf Chenia
      An increasing incidence of multidrug-resistant Aeromonas spp., which are both fish and emerging opportunistic human pathogens, has been observed worldwide. Quinolone–resistant Aeromonas spp. isolates are increasingly being observed in clinical and environmental settings, and this has been attributed primarily to target gene alterations, efflux, and transferable quinolone resistance. Thirty-four Aeromonas spp., obtained from freshwater aquaculture systems, were screened for the presence of GyrA and ParC substitutions, efflux activity and the prevalence of plasmid-mediated quinolone resistance genes, qnr and aac-6′-Ib-cr. Although 44% of isolates were resistant to nalidixic acid, the majority were susceptible to ciprofloxacin and ofloxacin. The predominant GyrA substitution was Ser-83→Val among Aeromonas veronii isolates whilst Aeromonas hydrophila isolates displayed a Ser-83→Ile substitution, and Ser-80→Ile substitutions were observed in ParC. Minimum inhibitory concentrations of fluoro(quinolones) were determined in the presence and absence of the efflux pump inhibitor, phenylalanine-arginine β-naphthylamide (PAβN). Addition of PAβN had no effect on the levels of fluoro(quinolone) resistance observed for these isolates. Although no aac-6′-Ib-cr variant genes were identified, qnrB and qnrS were detected for 41% and 24% of isolates, respectively, by Southern hybridization and confirmed by PCR and sequencing. Quinolone resistance in these fish-associated Aeromonas isolates was related to mutations in the quinolone resistance determining regions of GyrA and ParC and presence of qnrB and qnrS. The presence of qnr alleles in Aeromonas spp. isolates may facilitate high-level fluoroquinolone resistance and potentially serve as reservoirs for the dissemination of qnr genes to other aquatic microbes.


      PubDate: 2016-05-15T23:37:35Z
       
  • Survival and growth of Cronobacter sakazakii on fresh-cut fruit and the
           effect of UV-C illumination and electrolyzed water in the reduction of its
           population
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): David Santo, Ana Graça, Carla Nunes, Célia Quintas
      Cronobacter sakazakii, found in foods such as powdered infant formula and plant origin ready-to-eat food, is an opportunistic pathogen to infants, neonates and vulnerable adults. The objective of this study was to monitor the growth of C. sakazakii in fresh-cut ‘Royal gala’ apple, ‘Rocha’ pear, and ‘Piel de sapo’ melon, and the effect of UV-C illumination, acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW) in the reduction of its population. Fresh-cut fruits were inoculated and incubated at different temperatures during 10days while monitoring C. sakazakii. The inhibitory activity of different doses of UV-C (0–10kJ.m2), electrolyzed water and sodium hypochlorite (SH) (100ppm chlorine) was evaluated on the fruits inoculated with C. sakazakii. The bacterium showed a significant growth in the fruits at 12 and 20°C, but did not grow at 4°C, despite having survived for 10days. At 8°C, adaptation phases of 0.6–3.9days were estimated in the fruits before exponential growth. The UV-C 7.5 and 10kJ/m2 produced greater C. sakazakii population decreases (2–2.4logcfu/g) than AEW (1.3–1.8logcfu/g), NEW (1–1.2logcfu/g) and SH (0.8–1.4logcfu/g). The UV-C decontamination system and refrigeration at 4°C, may contribute to the product's safety and quality. The results help better understand the behavior of C. sakazakii on fresh-cut fruit alerting producers of the necessity to respect the high hygienic practices, adequate refrigerating temperature maintenance and caution with the tendency to prolong the validity of this kind of ready-to-eat food.


      PubDate: 2016-05-10T09:50:58Z
       
  • Inactivation of Salmonella, Listeria monocytogenes and Enterococcus
           faecium NRRL B-2354 in a selection of low moisture foods
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Grzegorz Rachon, Walter Peñaloza, Paul A. Gibbs
      The aims of this study were to obtain data on survival and heat resistance of cocktails of Salmonella, Listeria monocytogenes and the surrogate Enterococcus faecium (NRRL B-2354) in four low moisture foods (confectionery formulation, chicken meat powder, pet food and savoury seasoning) during storage before processing. Inoculated samples were stored at 16°C and cell viability examined at day 0, 3, 7 and 21. At each time point, the heat resistance at 80°C was determined. The purpose was to determine a suitable storage time of inoculated foods that can be applied in heat resistance studies or process validations with similar cell viability and heat resistance characteristics. The main inactivation study was carried out within 7days after inoculation, the heat resistance of each bacterial cocktail was evaluated in each low moisture food heated in thermal cells exposed to temperatures between 70 and 140°C. The Weibull model and the first order kinetics (D-value) were used to express inactivation data and calculate the heating time to achieve 5 log reduction at each temperature. Results showed that the pathogens Salmonella and L. monocytogenes and the surrogate E. faecium NRRL B-2354, can survive well (maximum reduction <0.8 log) in low moisture foods maintained at 16°C, as simulation of warehouse raw material storage in winter and before processing. The D80 value of the pathogens and surrogate did not significantly change during the 21day storage (p>0.05). The inactivation kinetics of the pathogens and surrogate at temperatures between 70 and 140°C, were different between each organism and product. E. faecium NRRL B-2354 was a suitable Salmonella surrogate for three of the low moisture foods studied, but not for the sugar-containing confectionery formulation. Heating low moisture food in moisture-tight environments (thermal cells) to 111.2, 105.3 or 111.8°C can inactivate 5 log of Salmonella, L. monocytogenes or E. faecium NRRL B-2354 respectively.


      PubDate: 2016-05-10T09:50:58Z
       
  • Biocontrol of geosmin-producing Streptomyces spp. by two Bacillus strains
           from Chinese liquor
    • Abstract: Publication date: 16 August 2016
      Source:International Journal of Food Microbiology, Volume 231
      Author(s): Yan Zhi, Qun Wu, Hai Du, Yan Xu
      Streptomyces spp. producing geosmin have been regarded as the most frequent and serious microbial contamination causing earthy off-flavor in Chinese liquor. It is therefore necessary to control the Streptomyces community during liquor fermentation. Biological control, using the native microbiota present in liquor making, appears to be a better solution than chemical methods. The objective of this study was to isolate native microbiota antagonistic toward Streptomyces spp. and then to evaluate the possible action mode of the antagonists. Fourteen Bacillus strains isolated from different Daqu (the fermentation starter) showed antagonistic activity against Streptomyces sampsonii, which is one of the dominant geosmin producers. Bacillus subtilis 2–16 and Bacillus amyloliquefaciens 1–45 from Maotai Daqu significantly inhibited the growth of S. sampsonii by 57.8% and 84.3% respectively, and effectively prevented the geosmin production in the simulated fermentation experiments (inoculation ratio 1:1). To probe the biocontrol mode, the ability of strain 2–16 and 1–45 to produce antimicrobial metabolites and to reduce geosmin in the fermentation system was investigated. Antimicrobial substances were identified as lipopeptides by ultra-performance liquid chromatography tandem electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI/Q-TOF MS) and in vitro antibiotic assay. In addition, strains 2–16 and 1–45 were able to remove 45% and 15% of the geosmin respectively in the simulated solid-state fermentation. This study highlighted the potential of biocontrol, and how the use of native Bacillus species in Daqu could provide an eco-friendly method to prevent growth of Streptomyces spp. and geosmin contamination in Chinese liquor fermentation.


      PubDate: 2016-05-10T09:50:58Z
       
  • Predicting outgrowth and inactivation of Clostridium perfringens in meat
           products during low temperature long time heat treatment
    • Abstract: Publication date: 2 August 2016
      Source:International Journal of Food Microbiology, Volume 230
      Author(s): Zhi Duan, Terese Holst Hansen, Tina Beck Hansen, Paw Dalgaard, Susanne Knøchel
      With low temperature long time (LTLT) cooking it can take hours for meat to reach a final core temperature above 53°C and germination followed by growth of Clostridium perfringens is a concern. Available and new growth data in meats including 154 lag times (t lag), 224 maximum specific growth rates (μmax) and 25 maximum population densities (N max) were used to developed a model to predict growth of C. perfringens during the coming-up time of LTLT cooking. New data were generate in 26 challenge tests with chicken (pH6.8) and pork (pH5.6) at two different slowly increasing temperature (SIT) profiles (10°C to 53°C) followed by 53°C in up to 30h in total. Three inoculum types were studied including vegetative cells, non-heated spores and heat activated (75°C, 20min) spores of C. perfringens strain 790-94. Concentrations of vegetative cells in chicken increased 2 to 3logCFU/g during the SIT profiles. Similar results were found for non-heated and heated spores in chicken, whereas in pork C. perfringens 790-94 increased less than 1logCFU/g. At 53°C C. perfringens 790-94 was log-linearly inactivated. Observed and predicted concentrations of C. perfringens, at the time when 53°C (log(N53)) was reached, were used to evaluate the new growth model and three available predictive models previously published for C. perfringens growth during cooling rather than during SIT profiles. Model performance was evaluated by using mean deviation (MD), mean absolute deviation (MAD) and the acceptable simulation zone (ASZ) approach with a zone of ±0.5logCFU/g. The new model showed best performance with MD=0.27logCFU/g, MAD=0.66logCFU/g and ASZ=67%. The two growth models that performed best, were used together with a log-linear inactivation model and D53-values from the present study to simulate the behaviour of C. perfringens under the fast and slow SIT profiles investigated in the present study. Observed and predicted concentrations were compared using a new fail-safe acceptable zone (FSAZ) method. FSAZ was defined as the predicted concentration of C. perfringens plus 0.5logCFU/g. If at least 85% of the observed log-counts were below the FSAZ, the model was considered fail-safe. The two models showed similar performance but none of them performed satisfactorily for all conditions. It is recommended to use the models without a lag phase until more precise lag time models become available.


      PubDate: 2016-04-28T08:29:12Z
       
  • Effect of electrical field strength applied by PEF processing and storage
           temperature on the outgrowth of yeasts and moulds naturally present in a
           fresh fruit smoothie
    • Abstract: Publication date: 2 August 2016
      Source:International Journal of Food Microbiology, Volume 230
      Author(s): R.A.H. Timmermans, A.L. Nederhoff, M.N. Nierop Groot, M.A.J.S. van Boekel, H.C. Mastwijk
      Pulsed electrical field (PEF) technology offers an alternative to thermal pasteurisation of high-acid fruit juices, by extending the shelf life of food products, while retaining its fresh taste and nutritional value. Substantial research has been performed on the effect of electrical field strength on the inactivation kinetics of spoilage and pathogenic micro-organisms and on the outgrowth of spoilage micro-organisms during shelf life. However, studies on the effect of electrical field strength on the inactivation and outgrowth of surviving populations during shelf life are missing. In this study, we assessed the influence of electrical field strength applied by PEF processing and storage temperature on the outgrowth of surviving yeast and mould populations naturally present in fresh fruit smoothie in time. Therefore, an apple–strawberry–banana smoothie was treated in a continuous-flow PEF system (130L/h), using similar inlet and outlet conditions (preheating temperature 41°C, maximum temperature 58°C) to assure that the amount of energy across the different conditions was kept constant. Smoothies treated with variable electrical field strengths (13.5, 17.0, 20.0 and 24.0kV/cm) were compared to smoothies without treatment for outgrowth of yeasts and moulds. Outgrowth of yeasts and moulds stored at 4°C and 7°C was analysed by plating and visual observation and yeast growth was modelled using the modified logistic growth model (Zwietering model). Results showed that the intensity of the electrical field strength had an influence on the degree of inactivation of yeast cells, resulting in a faster outgrowth over time at lower electrical field strength. Outgrowth of moulds over time was not affected by the intensity of the electrical field strength used. Application of PEF introduces a trade-off between type of spoilage: in untreated smoothie yeasts lead to spoilage after 8days when stored at 4 or 7°C, whereas in PEF treated smoothie yeasts were (partly) inactivated and provided outgrowth opportunities for moulds, which led to spoilage by moulds after 14days (7°C) or 18days (4°C).


      PubDate: 2016-04-24T08:26:37Z
       
  • Phage sensitivity and prophage carriage in Staphylococcus aureus isolated
           from foods in Spain and New Zealand
    • Abstract: Publication date: 2 August 2016
      Source:International Journal of Food Microbiology, Volume 230
      Author(s): Diana Gutiérrez, Lorena Rodríguez-Rubio, Pilar García, Craig Billington, Aruni Premarante, Ana Rodríguez, Beatriz Martínez
      Bacteriophages (phages) are a promising tool for the biocontrol of pathogenic bacteria, including those contaminating food products and causing infectious diseases. However, the success of phage preparations is limited by the host ranges of their constituent phages. The phage resistance/sensitivity profile of eighty seven Staphylococcus aureus strains isolated in Spain and New Zealand from dairy, meat and seafood sources was determined for six phages (Φ11, K, ΦH5, ΦA72, CAPSa1 and CAPSa3). Most of the S. aureus strains were sensitive to phage K (Myoviridae) and CAPSa1 (Siphoviridae) regardless of their origin. There was a higher sensitivity of New Zealand S. aureus strains to phages isolated from both Spain (ΦH5 and ΦA72) and New Zealand (CAPSa1 and CAPSa3). Spanish phages had a higher infectivity on S. aureus strains of Spanish dairy origin, while Spanish strains isolated from other environments were more sensitive to New Zealand phages. Lysogeny was more prevalent in Spanish S. aureus compared to New Zealand strains. A multiplex PCR reaction, which detected ΦH5 and ΦA72 sequences, indicated a high prevalence of these prophages in Spanish S. aureus strains, but were infrequently detected in New Zealand strains. Overall, the correlation between phage resistance and lysogeny in S. aureus strains was found to be weak.


      PubDate: 2016-04-24T08:26:37Z
       
  • Seroprevalence of Toxoplasma gondii and direct genotyping using
           minisequencing in free-range pigs in Burkina Faso
    • Abstract: Publication date: 2 August 2016
      Source:International Journal of Food Microbiology, Volume 230
      Author(s): Sanata Bamba, Lénaïg Halos, Zékiba Tarnagda, Alexandre Alanio, Pauline Macé, Sandrine Moukoury, Ibrahim Sangaré, Robert Guiguemdé, Jean-Marc Costa, Stéphane Bretagne
      Background Swine are a major source of meat for humans. As such, they can play an important role in the epidemiology of human toxoplasmosis. Therefore, we performed an epidemiological study to determine the prevalence and genotypes of Toxoplasma gondii in Burkina Fasan swine. Methods The prevalence of T. gondii infection was evaluated in a 3-month prospective study at the slaughterhouse of Bobo-Dioulasso, Burkina Faso. Anti-Toxoplasma IgG titers were determined on meat juices from pig diaphragms using a commercially available ELISA assay. The DNA was extracted from 25mg of heart biopsies of seropositive animals (IgG ≥50% of the control) and the presence of T. gondii DNA was detected using a quantitative PCR assay. Genotyping was performed directly on DNA from PCR-positive biopsies using high-resolution melting and minisequencing analyses of the repeated B1 gene. Results The prevalence of carcasses positive for anti-Toxoplasma IgG was 29% (87/300) with no difference according to sex and age in contrast to the village of origin (p=0.018). Of the 87 seropositive animals, two were PCR positive (parasitic load at 64 and 128 parasites/mg of heart biopsy). Two new genotypes belonging to Type II and Type III and different from the genotypes previously described using minisequencing were identified. Conclusion Our study provides the first T. gondii seroprevalence data in Burkina Fasan swine. In addition, this direct typing method suggests diversity of the T. gondii genotypes circulating in domestic animals in Burkina Faso. This needs to be confirmed on a wider sampling of subjects.


      PubDate: 2016-04-24T08:26:37Z
       
  • Induction of simultaneous and sequential malolactic fermentation in durian
           wine
    • Abstract: Publication date: 2 August 2016
      Source:International Journal of Food Microbiology, Volume 230
      Author(s): Fransisca Taniasuri, Pin-Rou Lee, Shao-Quan Liu
      This study represented for the first time the impact of malolactic fermentation (MLF) induced by Oenococcus oeni and its inoculation strategies (simultaneous vs. sequential) on the fermentation performance as well as aroma compound profile of durian wine. There was no negative impact of simultaneous inoculation of O. oeni and Saccharomyces cerevisiae on the growth and fermentation kinetics of S. cerevisiae as compared to sequential fermentation. Simultaneous MLF did not lead to an excessive increase in volatile acidity as compared to sequential MLF. The kinetic changes of organic acids (i.e. malic, lactic, succinic, acetic and α-ketoglutaric acids) varied with simultaneous and sequential MLF relative to yeast alone. MLF, regardless of inoculation mode, resulted in higher production of fermentation-derived volatiles as compared to control (alcoholic fermentation only), including esters, volatile fatty acids, and terpenes, except for higher alcohols. Most indigenous volatile sulphur compounds in durian were decreased to trace levels with little differences among the control, simultaneous and sequential MLF. Among the different wines, the wine with simultaneous MLF had higher concentrations of terpenes and acetate esters while sequential MLF had increased concentrations of medium- and long-chain ethyl esters. Relative to alcoholic fermentation only, both simultaneous and sequential MLF reduced acetaldehyde substantially with sequential MLF being more effective. These findings illustrate that MLF is an effective and novel way of modulating the volatile and aroma compound profile of durian wine.


      PubDate: 2016-04-24T08:26:37Z
       
 
 
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