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  Subjects -> BIOLOGY (Total: 2912 journals)
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MICROBIOLOGY (241 journals)                  1 2 3     

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: 19)
Advances in Microbiology     Open Access   (Followers: 19)
Advances in Molecular Imaging     Open Access   (Followers: 1)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Microbiology Research     Open Access   (Followers: 1)
Algorithms for Molecular Biology     Open Access   (Followers: 4)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 16)
American Journal of Microbiological Research     Open Access  
American Journal of Microbiology     Open Access   (Followers: 15)
American Journal of Molecular Biology     Open Access   (Followers: 2)
American Journal of Stem Cell Research     Open Access   (Followers: 1)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 6)
Annals of Microbiology     Hybrid Journal   (Followers: 8)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 27)
Antimicrobial Agents and Chemotherapy     Full-text available via subscription   (Followers: 19)
Applied and Environmental Microbiology     Full-text available via subscription   (Followers: 37)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 9)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 32)
Archives of Microbiology     Hybrid Journal   (Followers: 5)
Avicenna Journal of Clinical Microbiology and Infection     Open Access  
Bangladesh Journal of Medical Microbiology     Open Access  
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
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: 4)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Biomolecular Detection and Quantification     Open Access  
Biomolecules     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 10)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases & Medical Microbiology     Hybrid Journal   (Followers: 2)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 3)
Cell Biology : Research & Therapy     Hybrid Journal   (Followers: 1)
Cell Host & Microbe     Full-text available via subscription   (Followers: 12)
Cell Medicine     Open Access   (Followers: 1)
Cell Regeneration     Open Access   (Followers: 1)
Cell Stem Cell     Full-text available via subscription   (Followers: 26)
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: 6)
Cellular Senescence and Therapy     Open Access  
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: 16)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 4)
Clinical Microbiology Reviews     Full-text available via subscription   (Followers: 11)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 9)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 10)
Current Clinical Microbiology Reports     Hybrid Journal   (Followers: 1)
Current Issues in Molecular Biology     Open Access   (Followers: 2)
Current Microbiology     Hybrid Journal   (Followers: 6)
Current Molecular Biology Reports     Hybrid Journal   (Followers: 1)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 22)
Current Tissue Engineering     Hybrid Journal   (Followers: 1)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 4)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 6)
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: 3)
Environmental Microbiology     Hybrid Journal   (Followers: 14)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 3)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 6)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 3)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 11)
European Journal of Microbiology and Immunology     Open Access   (Followers: 10)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 5)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 6)
Fems Microbiology Letters     Hybrid Journal   (Followers: 15)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 19)
Fermentation     Open Access  
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 14)
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: 2)
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: 5)
Geomicrobiology Journal     Hybrid Journal   (Followers: 2)
Gut Microbes     Full-text available via subscription   (Followers: 5)
IAWA Journal     Hybrid Journal  
Indian Journal of Microbiology     Hybrid Journal   (Followers: 1)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 6)
Inside the Cell     Open Access  
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 5)

        1 2 3     

Journal Cover International Journal of Food Microbiology
  [SJR: 1.614]   [H-I: 121]   [13 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0168-1605
   Published by Elsevier Homepage  [2801 journals]
  • Killer toxin from several food-derived Debaryomyces hansenii strains
           effective against pathogenic Candida yeasts
    • Abstract: Publication date: 2 April 2016
      Source:International Journal of Food Microbiology, Volume 222
      Author(s): Nabaraj Banjara, Kenneth W. Nickerson, Mallory J. Suhr, Heather E. Hallen-Adams
      Candida yeasts are the dominant fungi in the healthy human microbiome, but are well-known for causing disease following a variety of perturbations. Evaluation of fungal populations from the healthy human gut revealed a significant negative correlation between the foodborne yeast, Debaryomyces hansenii, and Candida species. D. hansenii is reported to produce killer toxins (mycocins) effective against other yeast species. In order to better understand this phenomenon, a collection of 42 D. hansenii isolates was obtained from 22 cheeses and evaluated for killer activity against Candida albicans and Candida tropicalis over a range of temperatures and pH values. Twenty three strains demonstrated killer activity against both C. albicans and C. tropicalis, which was pH- and temperature-dependent, with no killer activity observed for any strain at pH6.5 or higher, or at ≥35°C (physiological conditions in the human gastrointestinal tract). A cell-free mycocin preparation showed transient killer activity against C. albicans at 35°C and a cheese sample containing a killer D. hansenii strain demonstrated sustained killer activity against both C. albicans and C. tropicalis. Together, these observations raise the possibility that D. hansenii could influence Candida populations in the gut.


      PubDate: 2016-01-30T10:40:53Z
       
  • Prevalence and pathogenic potential of Escherichia coli isolates from raw
           milk and raw milk cheese in Egypt
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Rabee A. Ombarak, Atsushi Hinenoya, Sharda Prasad Awasthi, Atsushi Iguchi, Ayaka Shima, Abdel-Rahman M. Elbagory, Shinji Yamasaki
      The objectives of this study were to investigate prevalence and pathogenic potential of Escherichia coli contaminating raw milk and its products in Egypt. Out of 187 dairy products including 72 raw milk samples, 55 Karish cheese and 60 Ras cheese, 222 E. coli isolates including 111, 89 and 22 were obtained from 55 raw milk samples (76.4%), 41 Karish cheese (74.5%), and 13 Ras cheese (21.7%), respectively. Isolated E. coli strains were examined for 24 representative virulence genes present in diarrheagenic E. coli (DEC) and extraintestinal pathogenic E. coli (ExPEC). Among DEC and ExPEC virulence factors, genes for enteropathogenic E. coli (eaeA, bfpA, EAF), enterohemorrhagic E. coli (stx1, stx2, eaeA), enterotoxigenic E. coli (elt, est), enteroinvasive E. coli (invE), enteroaggregative E. coli (Eagg, astA), diffusely adherent E. coli (daaD), ExPEC (cdt-I to cdt-V, cnf1, cnf2, hlyA) and putative adhesins (efa1, iha, ehaA, saa, and lpfA O113 ) were screened by colony hybridization assay. Out of 222 E. coli strains, 104 (46.8%) isolated from 69 (36.9%) samples carried one or more virulence genes. The most prevalent gene detected was lpfA O113 (40.5%), followed by ehaA (32.4%,), astA (3.15%,), iha (1.80%), hlyA (1.35%), stx1 (0.90%), stx2 (0.90%), eaeA (0.45%), cdt-III (0.45%) and cnf2 (0.45%). Two strains isolated from Karish cheese harbored 5 virulence genes (stx1, stx2, iha, ehaA, lpfA O113 ). Stx subtype was determined to be stx1 (not stx1c or stx1d) and stx2d. Indeed, expression of hemolysin A, CDT-III, CNF-II, Stx1 and Stx2d was confirmed by blood agar plate, cytotoxicity assay and Western blotting, respectively. Among the 222 E. coli strains, 54 (48.6%), 38 (42.6%) and 12 (54.7%) isolated from raw milk, Karish cheese and Ras cheese were potentially virulent, respectively. O-genotyping indicated that most of the potentially virulent E. coli isolates did not belong to clinically important O serogroups except O75, O91 and O166, which have been associated with human diseases. Phylogenetic grouping revealed that 150 (67.6%), 67 (30.2%) and 5 (2.30%) strains were clustered into A, B1 and D groups, respectively, which are considered to be associated with intestinal infection, indicating that these E. coli strains might have a potential to cause gastroenteritis. To the best of our knowledge, this is the first comprehensive study regarding prevalence and pathogenic potential of E. coli in dairy products in Egypt. Raw milk, Karish cheese and Ras cheese in Egypt are highly contaminated with E. coli including potentially pathogenic strains, which may impose a public health threat.


      PubDate: 2016-01-30T10:40:53Z
       
  • Influence of cyclopropane fatty acids on heat, high pressure, acid and
           oxidative resistance in Escherichia coli
    • Abstract: Publication date: 2 April 2016
      Source:International Journal of Food Microbiology, Volume 222
      Author(s): Yuan Yao Chen, Michael G. Gänzle
      Heat and high pressure resistant strains of Escherichia coli are a challenge to food safety. This study investigated effects of cyclopropane fatty acids (CFAs) on stress tolerance in the heat- and pressure-resistant strain E. coli AW1.7 and the sensitive strain E. coli MG1655. The role of CFAs was explored by disruption of cfa coding for CFA synthase with an in-frame, unmarked deletion method. Both wild-type strains consumed all the unsaturated fatty acids (C16:1 and C18:1) that were mostly converted to CFAs and a low proportion to saturated fatty acid (C16:0). Moreover, E. coli AW1.7 contained a higher proportion of membrane C19:0 cyclopropane fatty acid than E. coli MG1655 (P <0.05). The Δcfa mutant strains did not produce CFAs, and the corresponding substrates C16:1 and C18:1 accumulated in membrane lipids. The deletion of cfa did not alter resistance to H2O2 but increased the lethality of heat, high pressure and acid treatments in E. coli AW1.7, and E. coli MG1655. E. coli AW1.7 and its Δcfa mutant were more resistant to pressure and heat but less resistant to acid stress than E. coli MG1655. Heat resistance of wild-type strains and their Δcfa mutant was also assessed in beef patties grilled to an internal temperature of 71°C. After treatment, cell counts of wild type strains were higher than those of the Δcfa mutant strains. In conclusion, CFA synthesis in E. coli increases heat, high pressure and acid resistance, and increases heat resistance in food. This knowledge on mechanisms of stress resistance will facilitate the design of intervention methods for improved pathogen control in food production.


      PubDate: 2016-01-30T10:40:53Z
       
  • Draft genome sequence and chemical profiling of Fusarium langsethiae, an
           emerging producer of type A trichothecenes
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Erik Lysøe, Rasmus J.N. Frandsen, Hege H. Divon, Valeria Terzi, Luigi Orrù, Antonella Lamontanara, Anna-Karin Kolseth, Kristian F. Nielsen, Ulf Thrane
      Fusarium langsethiae is a widespread pathogen of small grain cereals, causing problems with T-2 and HT-2 toxin contamination in grains every year. In an effort to better understand the biology of this fungus, we present a draft genome sequence of F. langsethiae Fl201059 isolated from oats in Norway. The assembly was fragmented, but reveals a genome of approximately 37.5Mb, with a GC content around 48%, and 12,232 predicted protein-coding genes. Focusing on secondary metabolism we identified candidate genes for 12 polyketide synthases, 13 non-ribosomal peptide synthetases, and 22 genes for terpene/isoprenoid biosynthesis. Some of these were found to be unique compared to sequence databases. The identified putative Tri5 cluster was highly syntenic to the cluster reported in F. sporotrichioides. Fusarium langsethiae Fl201059 produces a high number of secondary metabolites on Yeast Extract Sucrose (YES) agar medium, dominated by type A trichothecenes. Interestingly we found production of glucosylated HT-2 toxin (Glu-HT-2), previously suggested to be formed by the host plant and not by the fungus itself. In greenhouse inoculations of F. langsethiae Fl201059 on barley and oats, we detected the type A trichothecenes: neosolaniol, HT-2 toxin, T-2 toxin, Glu-HT-2 and numerous derivatives of these.


      PubDate: 2016-01-24T02:19:15Z
       
  • Comparative proteomic analysis of a potentially probiotic Lactobacillus
           pentosus MP-10 for the identification of key proteins involved in
           antibiotic resistance and biocide tolerance
    • Abstract: Publication date: Available online 22 January 2016
      Source:International Journal of Food Microbiology
      Author(s): María del Carmen Casado Muñoz, Nabil Benomar, Saïd Ennahar, Peter Horvatovich, Leyre Lavilla Lerma, Charles W. Knapp, Antonio Gálvez, Hikmate Abriouel
      Probiotic bacterial cultures require resistance mechanisms to avoid stress-related responses under challenging environmental conditions; however, understanding these traits is required to discern their utility in fermentative food preparations, versus clinical and agricultural risk. Here, we compared the proteomic responses of Lb. pentosus MP-10, a potentially probiotic lactic acid bacteria isolated from brines of naturally fermented Aloreña green table olives, exposed to sub-lethal concentrations of antibiotics (amoxicillin, chloramphenicol and tetracycline) and biocides (benzalkonium chloride and triclosan). Several genes became differentially expressed depending on antimicrobial exposure, such as the up-regulation of protein synthesis, and the down-regulation of carbohydrate metabolism and energy production. The antimicrobials appeared to have altered Lb. pentosus MP-10 physiology to achieve a gain of cellular energy for survival. For example, biocide-adapted Lb. pentosus MP-10 exhibited a down-regulated phosphocarrier protein HPr and an unexpressed oxidoreductase. However, protein synthesis was over-expressed in antibiotic- and biocide-adapted cells (ribosomal proteins and glutamyl-tRNA synthetase), possibly to compensate for damaged proteins targeted by antimicrobials. Furthermore, stress proteins, such as NADH peroxidase (Npx) and a small heat shock protein, were only over-expressed in antibiotic-adapted Lb. pentosus MP-10. Results showed that adaptation to sub-lethal concentrations of antimicrobials could be a good way to achieve desirable robustness of the probiotic Lb. pentosus MP-10 to various environmental and gastrointestinal conditions (e.g., acid and bile stresses).


      PubDate: 2016-01-24T02:19:15Z
       
  • Prospecting for the incidence of genes involved in ochratoxin and
           fumonisin biosynthesis in Brazilian strains of Aspergillus niger and
           Aspergillus welwitschiae
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Fernanda Pelisson Massi, Daniele Sartori, Larissa de Souza Ferranti, Beatriz Thie Iamanaka, Marta Hiromi Taniwaki, Maria Lucia Carneiro Vieira, Maria Helena Pelegrinelli Fungaro
      Aspergillus niger “aggregate” is an informal taxonomic rank that represents a group of species from the section Nigri. Among A. niger “aggregate” species Aspergillus niger sensu stricto and its cryptic species Aspergillus welwitschiae (= Aspergillus awamori sensu Perrone) are proven as ochratoxin A and fumonisin B2 producing species. A. niger has been frequently found in tropical and subtropical foods. A. welwitschiae is a new species, which was recently dismembered from the A. niger taxon. These species are morphologically very similar and molecular data are indispensable for their identification. A total of 175 Brazilian isolates previously identified as A. niger collected from dried fruits, Brazil nuts, coffee beans, grapes, cocoa and onions were investigated in this study. Based on partial calmodulin gene sequences about one-half of our isolates were identified as A. welwitschiae. This new species was the predominant species in onions analyzed in Brazil. A. niger and A. welwitschiae differ in their ability to produce ochratoxin A and fumonisin B2. Among A. niger isolates, approximately 32% were OTA producers, but in contrast only 1% of the A. welwitschiae isolates revealed the ability to produce ochratoxin A. Regarding fumonisin B2 production, there was a higher frequency of FB2 producing isolates in A. niger (74%) compared to A. welwitschiae (34%). Because not all A. niger and A. welwitschiae strains produce ochratoxin A and fumonisin B2, in this study a multiplex PCR was developed for detecting the presence of essential genes involved in ochratoxin (polyketide synthase and radHflavin-dependent halogenase) and fumonisin (α-oxoamine synthase) biosynthesis in the genome of A. niger and A. welwitschiae isolates. The frequency of strains harboring the mycotoxin genes was markedly different between A. niger and A. welwitschiae. All OTA producing isolates of A. niger and A. welwitschiae showed in their genome the pks and radH genes, and 95.2% of the nonproducing isolates did not contain these genes. The α-oxoamine synthase gene was detected in 100% and 36% of the A. niger and A. welwitschiae isolates, respectively. The loss of ochratoxin A production in A. niger and A. welwitschiae is highly associated with gene deletions within the ochratoxin biosynthetic gene cluster. The loss of fumonisin production in A. welwitschiae is associated with gene deletions within the fumonisin biosynthetic gene cluster, but this is not the case with A. niger.


      PubDate: 2016-01-24T02:19:15Z
       
  • Improvement of the antifungal activity of lactic acid bacteria by addition
           to the growth medium of phenylpyruvic acid, a precursor of phenyllactic
           acid
    • Abstract: Publication date: Available online 22 January 2016
      Source:International Journal of Food Microbiology
      Author(s): Francesca Valerio, Mariaelena Di Biase, Veronica M.T. Lattanzio, Paola Lavermicocca
      The aim of the current study was to improve the antifungal activity of eight lactic acid bacterial (LAB) strains by the addition of phenylpyruvic acid (PPA), a precursor of the antifungal compound phenyllactic acid (PLA), to a defined growth medium (DM). The effect of PPA addition on the LAB's antifungal activity related to the production of organic acids (PLA, D-lactic, L-lactic, acetic, citric, formic and 4-hydroxy-phenyllactic acids) and of other phenylpyruvic-derived molecules, was investigated. In the presence of PPA the inhibitory activity (expressed as growth inhibition percentage) against fungal bread contaminants Aspergillus niger and Penicillium roqueforti significantly increased and was, even if not completely, associated to PLA increase (from a mean value of 0.44 to 0.93mM). While the inhibitory activity against Endomyces fibuliger was mainly correlated to the low pH and to lactic, acetic and p-OH-PLA acids. When the PCA analysis based on data of growth inhibition percentage and organic acid concentrations was performed, strains grown in DM+PPA separated from those grown in DM and the most active strains Lactobacillus plantarum 21B, Lactobacillus fermentum 18B and Lactobacillus brevis 18F grouped together. The antifungal activity resulted to be strain-related, based on a different mechanism of action for filamentous fungi and the yeast and was not exclusively associated to the increase of PLA. Therefore, a further investigation on the unique unidentified peak in HPLC-UV chromatograms, was performed by LC–MS/MS analysis. Actually, full scan mass spectra (negative ion mode) recorded at the retention time of the unknown compound, showed a main peak of m/z 291.0 which was consistent with the nominal mass of the molecular ion [M-H]− of polyporic acid, a PPA derivative whose antifungal activity has been previously reported (Brewer et al., 1977). In conclusion, the addition of PPA to the growth medium contributed to improve the antifungal activity of LAB strains and resulted in the production of the polyporic acid, here ascertained in LAB strains.


      PubDate: 2016-01-24T02:19:15Z
       
  • The response of foodborne pathogens to osmotic and desiccation stresses in
           the food chain
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Catherine M. Burgess, Andrea Gianotti, Nadia Gruzdev, John Holah, Susanne Knøchel, Angelika Lehner, Edyta Margas, Stephan Schmitz Esser, Shlomo Sela (Saldinger), Odile Tresse
      In combination with other strategies, hyperosmolarity and desiccation are frequently used by the food processing industry as a means to prevent bacterial proliferation, and particularly that of foodborne pathogens, in food products. However, it is increasingly observed that bacteria, including human pathogens, encode mechanisms to survive and withstand these stresses. This review provides an overview of the mechanisms employed by Salmonella spp., Shiga toxin producing E. coli, Cronobacter spp., Listeria monocytogenes and Campylobacter spp. to tolerate osmotic and desiccation stresses and identifies gaps in knowledge which need to be addressed to ensure the safety of low water activity and desiccated food products.


      PubDate: 2016-01-24T02:19:15Z
       
  • Microbial diversity and metabolite composition of Belgian red-brown acidic
           ales
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Isabel Snauwaert, Sanne P. Roels, Filip Van Nieuwerburg, Anita Van Landschoot, Luc De Vuyst, Peter Vandamme
      Belgian red-brown acidic ales are sour and alcoholic fermented beers, which are produced by mixed-culture fermentation and blending. The brews are aged in oak barrels for about two years, after which mature beer is blended with young, non-aged beer to obtain the end-products. The present study evaluated the microbial community diversity of Belgian red-brown acidic ales at the end of the maturation phase of three subsequent brews of three different breweries. The microbial diversity was compared with the metabolite composition of the brews at the end of the maturation phase. Therefore, mature brew samples were subjected to 454 pyrosequencing of the 16S rRNA gene (bacteria) and the internal transcribed spacer region (yeasts) and a broad range of metabolites was quantified. The most important microbial species present in the Belgian red-brown acidic ales investigated were Pediococcus damnosus, Dekkera bruxellensis, and Acetobacter pasteurianus. In addition, this culture-independent analysis revealed operational taxonomic units that were assigned to an unclassified fungal community member, Candida, and Lactobacillus. The main metabolites present in the brew samples were l-lactic acid, d-lactic acid, and ethanol, whereas acetic acid was produced in lower quantities. The most prevailing aroma compounds were ethyl acetate, isoamyl acetate, ethyl hexanoate, and ethyl octanoate, which might be of impact on the aroma of the end-products.


      PubDate: 2016-01-24T02:19:15Z
       
  • Fungal biotransformation of chlorogenic and caffeic acids by Fusarium
           graminearum: New insights in the contribution of phenolic acids to
           resistance to deoxynivalenol accumulation in cereals
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Léa Gauthier, Marie-Noelle Bonnin-Verdal, Gisèle Marchegay, Laetitia Pinson-Gadais, Christine Ducos, Florence Richard-Forget, Vessela Atanasova-Penichon
      Fusarium Head Blight and Gibberella Ear Rot, mainly caused by the fungi Fusarium graminearum and Fusarium culmorum, are two of the most devastating diseases of small-grain cereals and maize. In addition to yield loss, these diseases frequently result in contamination of kernels with toxic type B trichothecenes. The potential involvement of chlorogenic acid in cereal resistance to Fusarium Head Blight and Gibberella Ear Rot and to trichothecene accumulation was the focus of this study. The effects of chlorogenic acid and one of its hydrolyzed products, caffeic acid, on fungal growth and type B trichothecenes biosynthesis were studied using concentrations close to physiological amounts quantified in kernels and a set of F. graminearum and F. culmorum strains. Both chlorogenic and caffeic acids negatively impact fungal growth and mycotoxin production, with caffeic acid being significantly more toxic. Inhibitory efficiencies of both phenolic acids were strain-dependent. To further investigate the antifungal and anti “mycotoxin” effect of chlorogenic and caffeic acids, the metabolic fate of these two phenolic acids was characterized in supplemented F. graminearum broths. For the first time, our results demonstrated the ability of F. graminearum to degrade chlorogenic acid into caffeic, hydroxychlorogenic and protocatechuic acids and caffeic acid into protocatechuic and hydroxycaffeic acids. Some of these metabolic products can contribute to the inhibitory efficiency of chlorogenic acid that, therefore, can be compared as a “pro-drug”. As a whole, our data corroborate the contribution of chlorogenic acid to the chemical defense that cereals employ to counteract F. graminearum and its production of mycotoxins.


      PubDate: 2016-01-24T02:19:15Z
       
  • Efficacy of salicylic acid to reduce Penicillium expansum inoculum and
           preserve apple fruits
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Argus Cezar da Rocha Neto, Caroline Luiz, Marcelo Maraschin, Robson Marcelo Di Piero
      Apples are among the most commonly consumed fruits worldwide. Blue mold (Penicillium expansum) is one of the major diseases in apples postharvest, leading to wide use of fungicides and the search for alternative products to control the pathogen. In this context, this study aimed to evaluate the potential of salicylic acid (SA) as an alternative product to control blue mold and to preserve the physicochemical characteristics of apple fruit postharvest. The antimicrobial effect of SA was determined both in vitro and in situ, by directly exposing conidia to solutions of different concentrations SA or by inoculating the fruit with P. expansum and treating them curatively, eradicatively, or preventively with a 2.5mM SA solution. The physiological effects of SA on fruit were determined by quantifying the weight loss, total soluble solids content, and titratable acidity. In addition, the accumulation of SA in the fruit was determined by HPLC. SA (2.5mM) inhibited 100% of fungal germination in vitro and also controlled blue mold in situ when applied eradicatively. In addition, HPLC analysis demonstrated that SA did not persist in apple fruit. SA also maintained the physicochemical characteristics of fruit of different quality categories. Thus, SA may be an alternative to the commercial fungicides currently used against P. expansum.


      PubDate: 2016-01-24T02:19:15Z
       
  • Active packaging with antifungal activities
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): N. Nguyen Van Long, Catherine Joly, Philippe Dantigny
      There have been many reviews concerned with antimicrobial food packaging, and with the use of antifungal compounds, but none provided an exhaustive picture of the applications of active packaging to control fungal spoilage. Very recently, many studies have been done in these fields, therefore it is timely to review this topic. This article examines the effects of essential oils, preservatives, natural products, chemical fungicides, nanoparticles coated to different films, and chitosan in vitro on the growth of moulds, but also in vivo on the mould free shelf-life of bread, cheese, and fresh fruits and vegetables. A short section is also dedicated to yeasts. All the applications are described from a microbiological point of view, and these were sorted depending on the name of the species. Methods and results obtained are discussed. Essential oils and preservatives were ranked by increased efficacy on mould growth. For all the tested molecules, Penicillium species were shown more sensitive than Aspergillus species. However, comparison between the results was difficult because it appeared that the efficiency of active packaging depended greatly on the environmental factors of food such as water activity, pH, temperature, NaCl concentration, the nature, the size, and the mode of application of the films, in addition to the fact that the amount of released antifungal compounds was not constant with time.


      PubDate: 2016-01-24T02:19:15Z
       
  • Characterization of antimicrobial lipopeptides produced by Bacillus sp.
           LM7 isolated from chungkookjang, a Korean traditional fermented soybean
           food
    • Abstract: Publication date: 16 March 2016
      Source:International Journal of Food Microbiology, Volume 221
      Author(s): Mi-Hwa Lee, Jiyeon Lee, Young-Do Nam, Jong Suk Lee, Myung-Ji Seo, Sung-Hun Yi
      A wild-type microorganism exhibiting antimicrobial activities was isolated from the Korean traditional fermented soybean food Chungkookjang and identified as Bacillus sp. LM7. During its stationary growth phase, the microorganism secreted an antimicrobial substance, which we partially purified using a simple two-step procedure involving ammonium sulfate precipitation and heat treatment. The partially purified antimicrobial substance, Anti-LM7, was stable over a broad pH range (4.0–9.0) and at temperatures up to 80°C for 30min, and was resistant to most proteolytic enzymes and maintained its activity in 30% (v/v) organic solvents. Anti-LM7 inhibited the growth of a broad range of Gram-positive bacteria, including Bacillus cereus and Listeria monocytogenes, but it did not inhibit lactic acid bacteria such as Lactobacillus plantarum and Lactococcus lactis subsp. Lactis. Moreover, unlike commercially available nisin and polymyxin B, Anti-LM7 inhibited certain fungal strains. Lastly, liquid chromatography-mass spectrometry analysis of Anti-LM7 revealed that it contained eight lipopeptides belonging to two families: four bacillomycin D and four surfactin analogs. These Bacillus sp. LM7-produced heterogeneous lipopeptides exhibiting extremely high stability and a broad antimicrobial spectrum are likely to be closely related to the antimicrobial activity of Chungkookjang, and their identification presents an opportunity for application of the peptides in environmental bioremediation, pharmaceutical, cosmetic, and food industries.


      PubDate: 2016-01-24T02:19:15Z
       
  • Isoepoxydon dehydrogenase (idh) gene expression in relation to patulin
           production by Penicillium expansum under different temperature and
           atmosphere
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): N. De Clercq, G. Vlaemynck, E. Van Pamel, S. Van Weyenberg, L. Herman, F. Devlieghere, B. De Meulenaer, E. Van Coillie
      Penicillium expansum growth and patulin production occur mainly at post-harvest stage during the long-term storage of apples. Low temperature in combination with reduced oxygen concentrations is commonly applied as a control strategy to extend apple shelf life and supply the market throughout the year. Our in vitro study investigated the effect of temperature and atmosphere on expression of the idh gene in relation to the patulin production by P. expansum. The idh gene encodes the isoepoxydon dehydrogenase enzyme, a key enzyme in the patulin biosynthesis pathway. First, a reverse transcription real-time PCR (RT-qPCR) method was optimized to measure accurately the P. expansum idh mRNA levels relative to the mRNA levels of three reference genes (18S, β-tubulin, calmodulin), taking into account important parameters such as PCR inhibition and multiple reference gene stability. Subsequently, two P. expansum field isolates and one reference strain were grown on apple puree agar medium (APAM) under three conditions of temperature and atmosphere: 20°C — air, 4°C — air and 4°C — controlled atmosphere (CA; 3% O2). When P. expansum strains reached a 0.5 and 2.0cm colony diameter, idh expression and patulin concentrations were determined by means of the developed RT-qPCR and an HPLC-UV method, respectively. The in vitro study showed a clear reduction in patulin production and down-regulation of the idh gene expression when P. expansum was grown under 4°C — CA. The results suggest that stress (low temperature and oxygen level) caused a delay of the fungal metabolism rather than a complete inhibition of toxin biosynthesis. A good correlation was found between the idh expression and patulin production, corroborating that temperature and atmosphere affected patulin production by acting at the transcriptional level of the idh gene. Finally, a reliable RT-qPCR can be considered as an alternative tool to investigate the effect of control strategies on the toxin formation in food.


      PubDate: 2016-01-20T01:59:55Z
       
  • PCR-denaturing gradient gel electrophoresis analysis of microbial
           community in soy-daddawa, a Nigerian fermented soybean (Glycine max (L.)
           Merr.) condiment
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Obinna T. Ezeokoli, Arvind K. Gupta, Charlotte Mienie, Temitope O.S. Popoola, Cornelius C. Bezuidenhout
      Soy-daddawa, a fermented soybean (Glycine max (L.) Merr.) condiment, plays a significant role in the culinary practice of West Africa. It is essential to understand the microbial community of soy-daddawa for a successful starter culture application. This study investigated the microbial community structure of soy-daddawa samples collected from Nigerian markets, by PCR-denaturing gradient gel electrophoresis (DGGE) targeting the V3–V5 region of the 16S rRNA gene of bacteria and internal transcribed spacer 2 (ITS2) region of fungi. Six bacterial and 16 fungal (nine yeasts and seven molds) operational taxonomic units (OTUs)/species were obtained at 97% sequence similarity. Taxonomic assignments revealed that bacterial OTUs belonged to the phyla Firmicutes and Actinobacteria, and included species from the genera Atopostipes, Bacillus, Brevibacterium and Nosocomiicoccus. Densitometric analysis of DGGE image/bands revealed that Bacillus spp. were the dominant OTU/species in terms of population numbers. Fungal OTUs belonged to the phyla Ascomycota and Zygomycota, and included species from the genera, Alternaria, Aspergillus, Candida, Cladosporium, Dokmaia, Issatchenkia, Kodamaea, Lecythophora, Phoma, Pichia, Rhizopus, Saccharomyces and Starmerella. The majority of fungal species have not been previously reported in soy-daddawa. Potential opportunistic human pathogens such as Atopostipes suicloacalis, Candida rugosa, Candida tropicalis, and Kodamaea ohmeri were detected. Variation in soy-daddawa microbial communities amongst samples and presence of potential opportunistic pathogens emphasises the need for starter culture employment and good handling practices in soy-daddawa processing.


      PubDate: 2016-01-20T01:59:55Z
       
  • Kombucha tea fermentation: Microbial and biochemical dynamics
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Somnath Chakravorty, Semantee Bhattacharya, Antonis Chatzinotas, Writachit Chakraborty, Debanjana Bhattacharya, Ratan Gachhui
      Kombucha tea, a non-alcoholic beverage, is acquiring significant interest due to its claimed beneficial properties. The microbial community of Kombucha tea consists of bacteria and yeast which thrive in two mutually non-exclusive compartments: the soup or the beverage and the biofilm floating on it. The microbial community and the biochemical properties of the beverage have so far mostly been described in separate studies. This, however, may prevent understanding the causal links between the microbial communities and the beneficial properties of Kombucha tea. Moreover, an extensive study into the microbial and biochemical dynamics has also been missing. In this study, we thus explored the structure and dynamics of the microbial community along with the biochemical properties of Kombucha tea at different time points up to 21days of fermentation. We hypothesized that several biochemical properties will change during the course of fermentation along with the shifts in the yeast and bacterial communities. The yeast community of the biofilm did not show much variation over time and was dominated by Candida sp. (73.5–83%). The soup however, showed a significant shift in dominance from Candida sp. to Lachancea sp. on the 7th day of fermentation. This is the first report showing Candida as the most dominating yeast genus during Kombucha fermentation. Komagateibacter was identified as the single largest bacterial genus present in both the biofilm and the soup (~50%). The bacterial diversity was higher in the soup than in the biofilm with a peak on the seventh day of fermentation. The biochemical properties changed with the progression of the fermentation, i.e., beneficial properties of the beverage such as the radical scavenging ability increased significantly with a maximum increase at day 7. We further observed a significantly higher d-saccharic acid-1,4-lactone content and caffeine degradation property compared to previously described Kombucha tea fermentations. Our data thus indicate that the microbial community structure and dynamics play an important role in the biochemistry of the fermentation of the beverage. We envisage that combined molecular and biochemical analyses like in our study will provide valuable insights for better understanding the role of the microbial community for the beneficial properties of the beverage.


      PubDate: 2016-01-20T01:59:55Z
       
  • Stability of active prophages in industrial Lactococcus lactis strains in
           the presence of heat, acid, osmotic, oxidative and antibiotic stressors
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Chun-Hoong Ho, Mitchell Stanton-Cook, Scott A. Beatson, Nidhi Bansal, Mark S. Turner
      Lactococcus lactis is a starter bacterium commonly used in cheese making where it has an important role in acid-mediated curd formation as well as the development of flavour compounds. Industrial L. lactis strains can harbour one or more inducible prophages which when induced can affect cell growth and possibly lead to cell lysis. This is undesirable during growth and fermentation, but can beneficially lead to faster release of enzymes during cheese ripening. Lactococci can encounter multiple stress inducing conditions during the production of cheese, such as low and high temperatures, low pH, high osmotic pressure and long-term incubation. In this study, we tested the effect of these industrial stressors on prophage induction in two cheese making L. lactis subsp. cremoris strains (ASCC890049 and ASCC890310) as well as the laboratory strain L. lactis MG1363. Firstly, in order to identify inducible prophages in these strains we exposed them to the prophage inducing chemical mitomycin C (MMC) for 1 and 2h and then subjected the total genomic DNA to next-generation Illumina sequencing. Mapping of sequence reads back to the genome sequences revealed regions which contained a much higher fold coverage indicating DNA replication. These regions were amplified by up to 332-fold per cell (relative to the control tufA gene) and were identified as having similarities to different subgroups of P335 phages including MG-5, TP901-1, ul36.k1, bIL286, TP712 and BK5-T. Next, quantitative PCR was used to confirm the strong induction of prophages by MMC and then determine the copy number of the inducible prophages following exposure to various growth inhibitory levels of HCl, lactic acid, high temperature, NaCl, hydrogen peroxide and bacitracin. With the exception of a slight induction (2 to 4-fold) with hydrogen peroxide and long-term incubation after 21days in one industrial strain, none of the other stressors induced prophage DNA replication. These findings show that the repression system that maintains prophages in the dormant state in cheese making lactococcal strains is very tight and that several stressors encountered singularly are not predicted to be major inducers of prophage activation.


      PubDate: 2016-01-16T01:51:27Z
       
  • Occurrence and molecular characterisation of Vibrio parahaemolyticus in
           crustaceans commercialised in Venice area, Italy
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Greta Caburlotto, Elisabetta Suffredini, Marica Toson, Luca Fasolato, Paolo Antonetti, Michela Zambon, Amedeo Manfrin
      Infections due to the pathogenic human vibrios, Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus, are mainly associated with consumption of raw or partially cooked bivalve molluscs. At present, little is known about the presence of Vibrio species in crustaceans and the risk of vibriosis associated with the consumption of these products. The aim of the present study was to evaluate the prevalence and concentration of the main pathogenic Vibrio spp. in samples of crustaceans (n =143) commonly eaten in Italy, taking into account the effects of different variables such as crustacean species, storage conditions and geographic origin. Subsequently, the potential pathogenicity of V. parahaemolyticus strains isolated from crustaceans (n =88) was investigated, considering the classic virulence factors (tdh and trh genes) and four genes coding for relevant proteins of the type III secretion systems 2 (T3SS2α and T3SS2β). In this study, the presence of V. cholerae and V. vulnificus was never detected, whereas 40 samples (28%) were positive for V. parahaemolyticus with an overall prevalence of 41% in refrigerated products and 8% in frozen products. The highest prevalence and average contamination levels were detected in Crangon crangon (prevalence 58% and median value 3400MPN/g) and in products from the northern Adriatic Sea (35%), with the samples from the northern Venetian Lagoon reaching a median value of 1375MPN/g. While genetic analysis confirmed absence of the tdh gene, three of the isolates contained the trh gene and, simultaneously, the T3SS2β genes. Moreover three possibly clonal tdh-negative/trh-negative isolates carried the T3SS2α apparatus. The detection of both T3SS2α and T3SS2β apparatuses in V. parahaemolyticus strains isolated from crustaceans emphasised the importance of considering new genetic markers associated with virulence besides the classical factors. Moreover this study represents the first report dealing with Vibrio spp. in crustaceans in Italy, and it may provide useful information for the development of sanitary surveillance plans to prevent the risk of vibriosis in seafood consumers.


      PubDate: 2016-01-16T01:51:27Z
       
  • Virulence gene expression, adhesion and invasion of Campylobacter jejuni
           exposed to oxidative stress (H2O2)
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Leonard Koolman, Paul Whyte, Catherine Burgess, Declan Bolton
      Studies were undertaken to investigate the effect of oxidative stress conditions (exposure to hydrogen peroxide, H2O2) on [1] the expression of 14 Campylobacter jejuni virulence-associated genes associated with motility and/or invasion (flaA, flaB, flhA, flhB, ciaB, iamA), adhesion (cadF), cytotoxin production (cdtA, cdtB, cdtC) as well as some of the regulators of these genes (rpoN, fliA, luxS, cj1000), in 10 C. jejuni strains (5 poultry and 5 human) and [2] the ability of these cells to adhere to and invade Caco-2 cells. Using 16S rRNA as the reference gene (preliminary research demonstrated that this gene was stably expressed), the expression of the 14 virulence associated genes was investigated under normal and oxidative stress conditions using reverse transcription PCR. A Caco-2 cell tissue culture assay was used to examine adhesion and invasion. The response to oxidative stress was strain-dependent. Two strains showed significant (p<0.05) up or down regulation in 7 of the 14 genes tested, while only 1–2 genes were affected in the remaining strains. Expression of cadF was significantly (p<0.05) changed in all strains, cdt B in 4 strains and cj1000 in 3 strains. Expression of the remaining genes was either unaffected or significantly altered in 1–2 strains. NCTC 11168 completely lost the ability to adhere to and invade Caco-2 cells. One other strain also demonstrated reduced adherence while two others were unable to invade Caco-2 cells after exposure to oxidative stress conditions. In contrast strain 7, a poultry isolate, showed increased invasion. It was concluded that oxidative stress affects expression of C. jejuni virulence genes in a strain-dependent manner, CadF may have a secondary survival function and the cdtB gene may have a different promoter than cdtA and cdtC.


      PubDate: 2016-01-16T01:51:27Z
       
  • Effectiveness of superheated steam for inactivation of Escherichia coli
           O157:H7, Salmonella Typhimurium, Salmonella Enteritidis phage type 30, and
           Listeria monocytogenes on almonds and pistachios
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Ga-Hee Ban, Dong-Hyun Kang
      This study was undertaken to evaluate the effectiveness of superheated steam (SHS) on the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, Salmonella Enteritidis phage type (PT) 30 and Listeria monocytogenes on almonds and in-shell pistachios and to determine the effect of superheated steam heating on quality by measuring color and texture changes. Almonds and in-shell pistachios inoculated with four foodborne pathogens were treated with saturated steam (SS) at 100°C and SHS at 125, 150, 175, and 200°C for various times. Exposure of almonds and pistachios to SHS for 15 or 30s at 200°C achieved >5log reductions among all tested pathogens without causing significant changes in color values or texture parameters (P >0.05). For both almonds and pistachios, acid and peroxide values (PV) following SS and SHS treatment for up to 15s and 30s, respectively, were within the acceptable range (PV<1.0meq/kg). These results show that thermal application of 200°C SHS treatment for 15s and 30s did not affect the quality of almonds and pistachios, respectively. Therefore, SHS treatment is a very promising alternative technology for the tree nuts industry by improving inactivation of foodborne pathogens on almonds and pistachios while simultaneously reducing processing time.


      PubDate: 2016-01-12T01:46:32Z
       
  • Effect of single or combined chemical and natural antimicrobial
           interventions on Escherichia coli O157:H7, total microbiota and color of
           packaged spinach and lettuce
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Sofia V. Poimenidou, Vasiliki C. Bikouli, Chryssavgi Gardeli, Christina Mitsi, Petros A. Tarantilis, George-John Nychas, Panagiotis N. Skandamis
      Aqueous extract of Origanum vulgare (oregano), sodium hypochlorite (60 and 300ppm of free chlorine), Citrox® (containing citric acid and phenolic compounds [bioflavonoids] as active ingredients), vinegar, lactic acid, and double combinations of Citrox, lactic acid and oregano were evaluated against Escherichia coli O157:H7 and total mesophilic microbiota on fresh-cut spinach and lettuce and for their impact on color of treated vegetables. Spinach and lettuce leaves were inoculated with E. coli O157:H7 to a level of 5–6logCFU/g and immersed in washing solutions for 2 or 5min at 20°C, followed by rinsing with ice water (30s). Bacterial populations on vegetables were enumerated immediately after washing and after storage of the samples at 5°C for 7days under 20% CO2: 80% N2. No significant post-washing microbial reductions were achieved by chlorinated water, whereas after storage total microbiota was increased by 2.4logCFU/g on lettuce. Vinegar wash was the most effective treatment causing E. coli O157:H7 reductions of 1.8–4.3logCFU/g. During storage, pathogen was further decreased to below the detection limit level (<2logCFU/g) and total microbiota exhibited the highest reductions compared to other treatments. Lactic acid reduced pathogen by 1.6–3.7logCFU/g after washing; however levels of total microbiota increased by up to 2logCFU/g on packaged lettuce during storage. Washing lettuce samples with oregano for 2min resulted in 2.1logCFU/g reduction of E. coli O157:H7. When Citrox was combined with oregano, 3.7–4.0logCFU/g reduction was achieved on spinach and lettuce samples, with no significant effect on color parameters. Additionally, rinsing with ice water after decontamination treatments contributed to maintenance of color of the treated vegetables. In conclusion, the results indicated that vinegar, lactic acid or oregano aqueous extract alone or in combination, as alternative washing solutions to chlorine, may be effectively used to control E. coli O157:H7 and sustain acceptable appearance of fresh cut spinach and lettuce.


      PubDate: 2016-01-08T08:53:09Z
       
  • Editorial Board
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219




      PubDate: 2016-01-08T08:53:09Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219




      PubDate: 2016-01-08T08:53:09Z
       
  • Development and evaluation of a RT-LAMP assay for rapid detection of
           hepatitis E virus from shellfish
    • Abstract: Publication date: 2 March 2016
      Source:International Journal of Food Microbiology, Volume 220
      Author(s): Shenyang Gao, Dandan Li, Ying Liu, Enhui Zha, Shen Wang, Yonggang Li, Tiezhong Zhou, Xiqing Yue
      Hepatitis E virus (HEV) has becoming a well known zoonotic enteric pathogen and circulated widely inter human–animal–water–food. Generally, detection of the virus has relied on conventional reverse transcription-PCR (RT-PCR) and TaqMan/SYBR quantitative real-time RT-PCR (RT-qPCR), but these tools are usually disadvantages in time-consuming and expensive instruments required. In the present study, we report here on the development of a one-step single-tube reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for rapid detection of HEV contamination in shellfish. The amplification is completed under the isothermal condition (63°C) for 60min, and can be visually evaluated by staining at a time in about 1h. In addition, a total of 315 shellfish (80 Anadara granosa, 115 Scapharca subcrenata and 120 Ruditapes philippinarum) collected monthly from the Jinzhou coastal estuary of China Bohai gulf were investigated for HEV contamination by the RT-LAMP compared with a standard RT-qPCR. It was found that genotype 4 HEV was detected in all three species of shellfish sampled using the RT-LAMP assay and was in accordance with RT-qPCR detection of HEV in shellfish. Summarily, our results indicate that the RT-LAMP is a rapid, specific, sensitive and reliable method. This method offers a new tool for the routine monitoring of HEV contamination in shellfish or its harvesting waters in field.


      PubDate: 2015-12-30T12:42:44Z
       
  • Evaluation of detection methods for non-O157 Shiga toxin-producing
           Escherichia coli from food
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Bavo Verhaegen, Inge Van Damme, Marc Heyndrickx, Nadine Botteldoorn, Mohamed Elhadidy, Karen Verstraete, Katelijne Dierick, Sarah Denayer, Lieven De Zutter, Koen De Reu
      Shiga toxin-producing Escherichia coli (STEC) remains a major foodborne pathogen of concern across the globe. Rapid detection and isolation of this pathogen is of great importance for public health reasons. In this study the detection and isolation of four non-O157 STEC strains (O26, O103, O111, O145) from different artificially contaminated matrices, namely ground (minced) beef, cattle carcass swab, lettuce mix and sprouted soy beans, were evaluated. Low amounts of STEC were used (0.25–1.40cfu/g) to spike the samples. All samples were enriched in parallel in Buffered Peptone Water (BPW) and Brila broth. After enrichment, detection was performed using real-time PCR (qPCR), and isolation using two chromogenic agar media, CHROMagar™ STEC and ChromID™ EHEC. Inoculation on the agar media was performed either directly after enrichment or after the use of an acid treatment procedure. Furthermore, the use of this procedure was also tested on naturally contaminated food products, using 150 stx-positive samples. Although the qPCR Cycle Threshold (Ct) values were lower after enrichment in Brila broth, no significant differences in recovery were observed between both enrichment broths. Both agar media were equally suitable for the isolation of STEC, although a significantly higher recovery was obtained when using both agar media in parallel. For samples with a Ct value above 25, an acid treatment step prior to isolation ensured a significant improvement in the recovery of STEC due to the reduction in background microbiota. This acid treatment procedure proved especially useful for the isolation of STEC from sprouted soy bean samples.


      PubDate: 2015-12-30T12:42:44Z
       
  • Bacterial diversity of Grenache and Carignan grape surface from different
           vineyards at Priorat wine region (Catalonia, Spain)
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Maria del Carmen Portillo, Judit Franquès, Isabel Araque, Cristina Reguant, Albert Bordons
      Epiphytic bacteria on grape berries play a critical role in grape health and quality, which decisively influence the winemaking process. Despite their importance, the bacteria related with grape berry surface remain understudied and most previous work has been based on culture-dependent methods, which offer a limited view of the actual diversity. Herein, we used high-throughput sequencing to investigate the bacterial diversity on the surface from two grape varieties, Grenache and Carignan, and compared them across five vineyards included within the Priorat region (Spain). We could detect up to 14 bacterial phyla with Firmicutes (37.6% Bacillales and 14% Lactobacillales), Proteobacteria (16.8% Pseudomonadales and 11.6% Enterobacteriales) and Actinobacteria (3.4% Actinomycetales) being the most abundant. Bacterial community was different at each vineyard being grape varietal, geographical situation and orientation related with changes in bacterial populations. The most abundant bacterial taxa and those driving differences between the vineyards and grape varietals were identified. This study indicates that bacterial community heterogeneities can be influenced by geographic factors like orientation.


      PubDate: 2015-12-30T12:42:44Z
       
  • Differential internalin A levels in biofilms of Listeria monocytogenes
           grown on different surfaces and nutrient conditions
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Niamh Gilmartin, Maria S. Gião, Charles W. Keevil, Richard O'Kennedy
      Listeria monoctyogenes is a foodborne pathogen containing the surface protein, internalin A (InlA). The expression of this protein permits the invasion of L. monocytogenes into intestinal epithelial cells expressing the receptor E-cadherin, thus crossing the intestinal barrier and resulting in listerosis. The main aim of this work was to investigate InlA levels in different L. monocytogenes strains in both planktonic and sessile states using an anti-InlA antibody. Biofilms were grown in high and low nutrient environments on glass, stainless steel and polytetrafluoroethylene (PTFE). This study demonstrated that InlA levels varied greatly between strains and serotypes of L. monocytogenes. However, the serotypes 1/2a, 1/2b and 4b, associated with the largest number of outbreaks of listerosis consistently showed the highest InlA levels, regardless of nutrient content or planktonic or sessile state. Differences in InlA levels were also observed in biofilms grown on different surfaces such as glass, stainless steel and PTFE, with a significant reduction in InlA levels observed in biofilms on PTFE. Interestingly, although a large number of the total cells observed in biofilms formed in tap-water were non-cultivable, the virulence factor, InlA, was expressed at levels between 78 and 85%, thus indicating that these cells may still be virulent. A greater understanding of the factors that affect the levels of InlA on the surface of L. monocytogenes, is essential in the appreciation of the role of InlA in the persistence of biofilms containing L. monocytogenes and their potential to cause food borne disease.


      PubDate: 2015-12-26T12:21:49Z
       
  • The effects of orange juice clarification on the physiology of Escherichia
           coli; growth-based and flow cytometric analysis
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Amir H.P. Anvarian, Madeleine P. Smith, Tim W. Overton
      Orange juice (OJ) is a food product available in various forms which can be processed to a greater or lesser extent. Minimally-processed OJ has a high consumer perception but presents a potential microbiological risk due to acid-tolerant bacteria. Clarification of OJ (such as removal of cloud) is a common processing step in many OJ products. However, many of the antimicrobial components of OJ such as essential oils are present in the cloud fraction. Here, the effect of clarification by filtration on the viability and physiology of Escherichia coli K-12 was tested using total viable count (TVC) and flow cytometric (FCM) analysis. The latter technique was also used to monitor intracellular pH during incubation in OJ. Removal of the OJ cloud fraction was shown to have dramatic effects on bacterial viability and physiology during storage at a range of incubation temperatures. For instance, at 4°C, a significantly lower number of healthy cells and a significantly higher number of injured cells were observed in 0.22μm-filtered OJ at 24h post-inoculation, compared to filtered OJ samples containing particles between 0.22μm and 11μm in size. Similarly, there was a significant difference between the number of healthy bacteria in the 0.7μm-filtered OJ and both 0.22μm-filtered and 1.2μm-filtered OJ after 24hour incubation at 22.5°C. This indicated that OJ cloud between 0.7μm and 0.22μm in size might have an adverse effect on the viability of E. coli K-12. Furthermore, FCM allowed the rapid analysis of bacterial physiology without the requirement for growth on agar plates, and revealed the extent of the viable but non-culturable (VBNC) population. For example, at 4°C, while the FCM viable count did not substantially decrease until 48h, decreases in TVC were observed between 0 and 48hour incubation, due to a subset of injured bacteria entering the VBNC state, hence being unable to grow on agar plates. This study highlights the application of FCM in monitoring bacterial physiology in foods, and potential effects of OJ clarification on bacterial physiology.


      PubDate: 2015-12-18T14:46:50Z
       
  • Development of a quantitative fluorescence single primer isothermal
           amplification-based method for the detection of Salmonella
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Jianchang Wang, Rui Li, Lianxia Hu, Xiaoxia Sun, Jinfeng Wang, Jing Li
      Food-borne disease caused by Salmonella has long been, and continues to be, an important global public health problem, necessitating rapid and accurate detection of Salmonella in food. Real time PCR is the most recently developed approach for Salmonella detection. Single primer isothermal amplification (SPIA), a novel gene amplification technique, has emerged as an attractive microbiological testing method. SPIA is performed under a constant temperature, eliminating the need for an expensive thermo-cycler. In addition, SPIA reactions can be accomplished in 30min, faster than real time PCR that usually takes over 2h. We developed a quantitative fluorescence SPIA-based method for the detection of Salmonella. Using Salmonella Typhimurium genomic DNA as template and a primer targeting Salmonella invA gene, we showed the detection limit of SPIA was 2.0×101 fg DNA. Its successful amplification of different serotypic Salmonella genomic DNA but not non-Salmonella bacterial DNA demonstrated the specificity of SPIA. Furthermore, this method was validated with artificially contaminated beef. In conclusion, we showed high sensitivity and specificity of SPIA in the detection of Salmonella, comparable to real time PCR. In addition, SPIA is faster and more cost-effective (non-use of expensive cyclers), making it a potential alternative for field detection of Salmonella in resource-limited settings that are commonly encountered in developing countries.


      PubDate: 2015-12-18T14:46:50Z
       
  • Influence of environmental parameters on mycotoxin production by
           Alternaria arborescens
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Sandra Vaquera, Andrea Patriarca, V. Fernández Pinto
      Alternaria arborescens has been reported as a common fungal species invading tomatoes and is capable of producing several mycotoxins in infected plants, fruits and in agricultural commodities. Alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA) are some of the main Alternaria mycotoxins that can be found as contaminants of food. This species can produce these toxic metabolites together with AAL toxins (Alternaria alternata f. sp. lycopersicum toxins), which can act as inhibitors of sphingolipid biosynthesis. The objective of this study was to determine the effect of water activity (aw, 0.995, 0.975, 0.950) and temperature (6, 15, 20, 25 and 30°C) on mycotoxin production by A. arborescens on a synthetic tomato medium. The optimum production of AOH and AME occurred at 0.975 aw after 40days of incubation at 30°C. The maximum TeA accumulation was observed at 0.975 aw and 25°C and at 0.950 aw and 30°C. AAL TA was produced in higher quantities at 0.995 aw and 30°C. At 6°C no quantifiable levels of AOH or AME were detected, but significant amounts of TeA were produced at 0.975 aw. In general, high aw levels and high temperatures were favorable for mycotoxin production. The greatest accumulation of all four toxins occurred at 0.975 aw and 30°C. The results obtained here could be extrapolated to evaluate the risk of tomato fruits and tomato products contamination caused by these toxins.


      PubDate: 2015-12-18T14:46:50Z
       
  • FoodMicrobionet: A database for the visualisation and exploration of food
           bacterial communities based on network analysis
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Eugenio Parente, Luca Cocolin, Francesca De Filippis, Teresa Zotta, Ilario Ferrocino, Orla O'Sullivan, Erasmo Neviani, Maria De Angelis, Paul D. Cotter, Danilo Ercolini
      Amplicon targeted high-throughput sequencing has become a popular tool for the culture-independent analysis of microbial communities. Although the data obtained with this approach are portable and the number of sequences available in public databases is increasing, no tool has been developed yet for the analysis and presentation of data obtained in different studies. This work describes an approach for the development of a database for the rapid exploration and analysis of data on food microbial communities. Data from seventeen studies investigating the structure of bacterial communities in dairy, meat, sourdough and fermented vegetable products, obtained by 16S rRNA gene targeted high-throughput sequencing, were collated and analysed using Gephi, a network analysis software. The resulting database, which we named FoodMicrobionet, was used to analyse nodes and network properties and to build an interactive web-based visualisation. The latter allows the visual exploration of the relationships between Operational Taxonomic Units (OTUs) and samples and the identification of core- and sample-specific bacterial communities. It also provides additional search tools and hyperlinks for the rapid selection of food groups and OTUs and for rapid access to external resources (NCBI taxonomy, digital versions of the original articles). Microbial interaction network analysis was carried out using CoNet on datasets extracted from FoodMicrobionet: the complexity of interaction networks was much lower than that found for other bacterial communities (human microbiome, soil and other environments). This may reflect both a bias in the dataset (which was dominated by fermented foods and starter cultures) and the lower complexity of food bacterial communities. Although some technical challenges exist, and are discussed here, the net result is a valuable tool for the exploration of food bacterial communities by the scientific community and food industry.


      PubDate: 2015-12-18T14:46:50Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218




      PubDate: 2015-12-18T14:46:50Z
       
  • Editorial Board
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218




      PubDate: 2015-12-18T14:46:50Z
       
  • Efficacy of oxidizing disinfectants at inactivating murine norovirus on
           ready-to-eat foods
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): Maryline Girard, Kirsten Mattison, Ismail Fliss, Julie Jean
      Noroviruses are the leading cause of foodborne illness, and ready-to-eat foods are frequent vehicles of their transmission. Studies of the disinfection of fruits and vegetables are becoming numerous. It has been shown that strong oxidizing agents are more effective than other chemical disinfectants for inactivating enteric viruses. The aim of this study was to evaluate the efficacy of oxidizing disinfectants (sodium hypochlorite, chloride dioxide and peracetic acid) at inactivating noroviruses on fruits and vegetables, using a norovirus surrogate, namely murine norovirus 3, which replicates in cell culture. Based on plaque assay, solutions of peracetic acid (85ppm) and chlorine dioxide (20ppm) reduced the infectivity of the virus in suspension by at least 3 log10 units after 1min, while sodium hypochlorite at 50ppm produced a 2-log reduction. On the surface of blueberries, strawberries and lettuce, chlorine dioxide was less effective than peracetic acid and sodium hypochlorite, which reduced viral titers by approximately 4 logs. A surprising increase in the efficacy of sodium hypochlorite on surfaces fouled with artificial feces was noted.


      PubDate: 2015-12-14T08:56:46Z
       
  • Thermal inactivation of Salmonella spp. in pork burger patties
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): P.M. Gurman, T. Ross, G.L. Holds, R.G. Jarrett, A. Kiermeier
      Predictive models, to estimate the reduction in Escherichia coli O157:H7 concentration in beef burgers, have been developed to inform risk management decisions; no analogous model exists for Salmonella spp. in pork burgers. In this study, “Extra Lean” and “Regular” fat pork minces were inoculated with Salmonella spp. (Salmonella 4,[5],12,i:-, Salmonella Senftenberg and Salmonella Typhimurium) and formed into pork burger patties. Patties were cooked on an electric skillet (to imitate home cooking) to one of seven internal temperatures (46, 49, 52, 55, 58, 61, 64°C) and Salmonella enumerated. A generalised linear logistic regression model was used to develop a predictive model for the Salmonella concentration based on the internal endpoint temperature. It was estimated that in pork mince with a fat content of 6.1%, Salmonella survival will be decreased by −0.2407log10 CFU/g for a 1°C increase in internal endpoint temperature, with a 5-log10 reduction in Salmonella concentration estimated to occur when the geometric centre temperature reaches 63°C. The fat content influenced the rate of Salmonella inactivation (P =0.043), with Salmonella survival increasing as fat content increased, though this effect became negligible as the temperature approached 62°C. Fat content increased the time required for patties to achieve a specified internal temperature (P =0.0106 and 0.0309 for linear and quadratic terms respectively), indicating that reduced fat pork mince may reduce the risk of salmonellosis from consumption of pork burgers. Salmonella serovar did not significantly affect the model intercepts (P =0.86) or slopes (P =0.10) of the fitted logistic curve. This predictive model can be applied to estimate the reduction in Salmonella in pork burgers after cooking to a specific endpoint temperature and hence to assess food safety risk.


      PubDate: 2015-12-14T08:56:46Z
       
  • The isolation and identification of Pantoea dispersa strain JFS as a
           non-pathogenic surrogate for Salmonella Typhimurium phage type 42 in flour
           
    • Abstract: Publication date: 16 February 2016
      Source:International Journal of Food Microbiology, Volume 219
      Author(s): James Fudge, Michael Dunn, Oscar Pike, Richard Robison, Frost Steele
      Salmonella is a common pathogen which has been the cause of foodborne illness outbreaks implicating a variety of commodities, including low-moisture foods such as flour. Salmonella costs more than any other pathogen in the United States in terms of health care expenses and time of lost work. Heat treatment can be used to reduce Salmonella and other pathogens in flour to safe levels. However, in low-moisture foods, process times must be increased to achieve adequate lethality, possibly resulting in changes in the flour's functionality such as changes in the gluten quality, vitamin content, and the level of starch gelatinization. There is a need to determine the minimal heat treatment required to achieve desired lethality in flour and other low-moisture foods, with the goal of retaining the flour's functionality. Currently there is no published data about a nonpathogenic bacterial surrogate for Salmonella in flour. In this study, a surrogate, which closely matches the thermal death rate of Salmonella in flour, has been isolated. The surrogate was identified following an evaluation of thermal death curves of ten different strains of bacteria isolated from heat-treated flour and two nonpathogenic surrogates used in other commodities. Flour samples were inoculated with Salmonella or one of the twelve bacterial isolates, and then subjected to heat (70, 75, and 80°C) for 12–60min. The heat tolerance for each organism was determined by plating out at least four different time points for each temperature and comparing the death curve to those from Salmonella. The death curve from Pantoea dispersa was not statistically different (p<0.05) than the death curve of Salmonella. This strain of P. dispersa (strain JFS) can be used as a conservative, slightly more heat resistant, surrogate for Salmonella. It can be used to verify the combination of heat and time necessary to kill Salmonella in flour using a commercial heat-treatment process.


      PubDate: 2015-12-14T08:56:46Z
       
  • Bacterial concentration and diversity in fresh tropical shrimps (Penaeus
           notialis) and the surrounding brackish waters and sediment
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): D. Sylvain Dabadé, Judith C.M. Wolkers-Rooijackers, Paulin Azokpota, D. Joseph Hounhouigan, Marcel H. Zwietering, M.J. Rob Nout, Heidy M.W. den Besten
      This study aimed at determining bacterial concentration and diversity in fresh tropical shrimps (Penaeus notialis) and their surrounding brackish waters and sediment. Freshly caught shrimp, water and sediment samples were collected in Lakes Nokoue and Aheme in Benin (West Africa) during two periods with different water salinity and temperature. We used complementary culture-dependent and culture-independent methods for microbiota analysis. During both sampling periods, total mesophilic aerobic counts in shrimp samples ranged between 4.4 and 5.9logCFU/g and were significantly higher than in water or sediment samples. In contrast, bacterial diversity was higher in sediment or water than in shrimps. The dominant phyla were Firmicutes and Proteobacteria in shrimps, Firmicutes, Proteobacteria, and Actinobacteria in water, and Proteobacteria and Chloroflexi in sediment. At species level, distinct bacterial communities were associated with sediment, water and shrimps sampled at the same site the same day. The study suggests that the bacterial community of tropical brackish water shrimps cannot be predicted from the microbiota of their aquatic environment. Thus, monitoring of microbiological quality of aquatic environments might not reflect shrimp microbiological quality.


      PubDate: 2015-12-09T08:53:37Z
       
  • Interactions between sanitizers and packaging gas compositions and their
           effects on the safety and quality of fresh-cut onions (Allium cepa L.)
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Natalie Page, Jaime González-Buesa, Elliot T. Ryser, Janice Harte, Eva Almenar
      Onions are one of the most widely utilized vegetables worldwide, with demand for fresh-cut onions steadily increasing. Due to heightened safety concerns and consumer demand, the implications of sanitizing and packaging on fresh-cut onion safety and quality need to be better understood. The objective of this study was to investigate the effect of produce sanitizers, in-package atmospheres, and their interactions on the growth of Salmonella Typhimurium, mesophilic aerobic bacteria, yeast and mold, and the physico-chemical quality of diced onions to determine the best sanitizer and in-package atmosphere combination for both safety and quality. Diced onions were inoculated or not with S. Typhimurium, sanitized in sodium hypochlorite, peroxyacetic acid, or liquid chlorine dioxide, and then packaged in either polylactic acid bags containing superatmospheric O2, elevated CO2/reduced O2, or air, or in polyethylene terephthalate snap-fit containers. Throughout 14days of storage at 7°C, packaged diced onions were assessed for their safety (S. Typhimurium), and quality (mesophilic aerobic bacteria, yeasts and molds, physico-chemical analyses, and descriptive and consumer acceptance sensory panels). While sanitizer affected (P <0.05) fewer parameters (S. Typhimurium, mesophiles, yeasts and molds, headspace CO2, weight loss, and pH), in-package atmosphere had a significant (P <0.05) effect on all parameters evaluated. Two-way interactions between sanitizer and atmosphere that affected S. Typhimurium and pH were identified whereas 3-way interactions (sanitizer, atmosphere and time) were only observed for headspace CO2. Sodium hypochlorite and elevated CO2/reduced O2 was the best sanitizer and in-package atmosphere combination for enhancing the safety and quality of packaged diced onions. In addition, this combination led to diced onions acceptable for purchase after 2weeks of storage by trained and consumer panels.


      PubDate: 2015-12-09T08:53:37Z
       
  • A study on the toxigenesis by Clostridium botulinum in nitrate and
           nitrite-reduced dry fermented sausages
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Xavier F. Hospital, Eva Hierro, Sandra Stringer, Manuela Fernández



      PubDate: 2015-11-26T17:03:38Z
       
  • Rapid prediction of ochratoxin A-producing strains of Penicillium on
           dry-cured meat by MOS-based electronic nose
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Vincenzo Lippolis, Massimo Ferrara, Salvatore Cervellieri, Anna Damascelli, Filomena Epifani, Michelangelo Pascale, Giancarlo Perrone
      The availability of rapid diagnostic methods for monitoring ochratoxigenic species during the seasoning processes for dry-cured meats is crucial and constitutes a key stage in order to prevent the risk of ochratoxin A (OTA) contamination. A rapid, easy-to-perform and non-invasive method using an electronic nose (e-nose) based on metal oxide semiconductors (MOS) was developed to discriminate dry-cured meat samples in two classes based on the fungal contamination: class P (samples contaminated by OTA-producing Penicillium strains) and class NP (samples contaminated by OTA non-producing Penicillium strains). Two OTA-producing strains of Penicillium nordicum and two OTA non-producing strains of Penicillium nalgiovense and Penicillium salamii, were tested. The feasibility of this approach was initially evaluated by e-nose analysis of 480 samples of both Yeast extract sucrose (YES) and meat-based agar media inoculated with the tested Penicillium strains and incubated up to 14days. The high recognition percentages (higher than 82%) obtained by Discriminant Function Analysis (DFA), either in calibration and cross-validation (leave-more-out approach), for both YES and meat-based samples demonstrated the validity of the used approach. The e-nose method was subsequently developed and validated for the analysis of dry-cured meat samples. A total of 240 e-nose analyses were carried out using inoculated sausages, seasoned by a laboratory-scale process and sampled at 5, 7, 10 and 14days. DFA provided calibration models that permitted discrimination of dry-cured meat samples after only 5days of seasoning with mean recognition percentages in calibration and cross-validation of 98 and 88%, respectively. A further validation of the developed e-nose method was performed using 60 dry-cured meat samples produced by an industrial-scale seasoning process showing a total recognition percentage of 73%. The pattern of volatile compounds of dry-cured meat samples was identified and characterized by a developed HS-SPME/GC–MS method. Seven volatile compounds (2-methyl-1-butanol, octane, 1R-α-pinene, d-limonene, undecane, tetradecanal, 9-(Z)-octadecenoic acid methyl ester) allowed discrimination between dry-cured meat samples of classes P and NP. These results demonstrate that MOS-based electronic nose can be a useful tool for a rapid screening in preventing OTA contamination in the cured meat supply chain.


      PubDate: 2015-11-26T17:03:38Z
       
  • Volatile organic compounds and Photobacterium phosphoreum associated with
           spoilage of modified-atmosphere-packaged raw pork
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Timo T. Nieminen, Paw Dalgaard, Johanna Björkroth
      Accumulation of volatile organic compounds was monitored in association with sensory quality, bacterial concentrations and culture-independent microbial community analyses in raw pork loin and pork collar during storage under high-oxygen modified atmosphere at +4°C. Of the 48 volatile compounds detected in the pork samples, the levels of acetoin, diacetyl and 3-methyl-1-butanol had the highest correlations with the sensory scores and bacterial concentrations. These compounds accumulated in all of the four monitored lots of non-sterile pork but not in the sterilized pork during chilled storage. According to the culture-dependent and culture-independent characterization of bacterial communities, Brochothrix thermosphacta, lactic acid bacteria (Carnobacterium, Lactobacillus, Lactococcus, Leuconostoc, Weissella) and Photobacterium spp. predominated in pork samples. Photobacterium spp., typically not associated with spoilage of meat, were detected also in 8 of the 11 retail packages of pork investigated subsequently. Eleven isolates from the pork samples were shown to belong to Photobacterium phosphoreum by phenotypic tests and sequencing of the 16S rRNA and gyrB gene fragments. Off-odors in pork samples with high proportion of Photobacterium spp. were associated with accumulation of acetoin, diacetyl and 3-methyl-1-butanol in meat, but these compounds did not explain all the off-odors reported in sensory analyses.


      PubDate: 2015-11-26T17:03:38Z
       
  • Streptomyces strains producing mitochondriotoxic antimycin A found in
           cereal grains
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Stiina Rasimus-Sahari, Raimo Mikkola, Maria A. Andersson, Marika Jestoi, Mirja Salkinoja-Salonen
      Reasons for mammalian cell toxicity observed in barley and spring wheat grains were sought. Streptomyces sp. isolates from wheat and barley produced heat-stable methanol-soluble substances which inhibited the motility of exposed porcine spermatozoa used as a toxicity indicator. Several barley isolates produced antimycin A (2 to 5ng/mg wet wt of biomass), a macrolide antibiotic known to block oxygen utilization in mitochondria. The antimycin-producing isolates were members of the Streptomyces albidoflavus group. In in vitro assays with porcine kidney tubular epithelial cells, the specific toxicity of antimycin A towards mitochondria was higher than that of the mycotoxin enniatin B but lower than that of the mitochondriotoxins cereulide and paenilide, produced by food-related Bacillus cereus and Paenibacillus tundrae, respectively. The toxic wheat isolates, related to Streptomyces sedi, did not produce antimycin A and or any other known toxin. Our results suggest that the presence of toxin-producing streptomycetes in stored cereal grains may pose a thus far unrecognized threat for food and feed safety.


      PubDate: 2015-11-26T17:03:38Z
       
  • Salmonella typhimurium detection using a surface-enhanced Raman
           scattering-based aptasensor
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Nuo Duan, Boya Chang, Hui Zhang, Zhouping Wang, Shijia Wu
      Surface-enhanced Raman spectroscopy (SERS) has been used in a variety of biological applications due to its high sensitivity and specificity. Here, we report a SERS-based aptasensor approach for quantitative detection of pathogenic bacteria. A SERS substrate bearing Au@Ag core/shell nanoparticles (NPs) is functionalized with aptamer 1 (apt 1) for the capture of target molecules. X-rhodamine (ROX)-modified aptamer 2 (apt 2) is used as recognition element and Raman reporter. Salmonella typhimurium specifically interacted with the aptamers to form Au@Ag-apt 1-target-apt 2-ROX sandwich-like complexes. As a result, the concentration of S. typhimurium was determined using this developed aptasensor structure, and a calibration curve is obtained in the range of 15 to 1.5×106 cfu/mL with a limit of detection of 15cfu/mL. Our method was successfully applied to real food samples, and the results are consistent with the results obtained using plate counting methods. We believe that the developed method shows potential for the rapid and sensitive detection of pathogenic bacteria in food safety assurance.


      PubDate: 2015-11-22T20:46:09Z
       
  • Aroma compounds generation in citrate metabolism of Enterococcus faecium:
           Genetic characterization of type I citrate gene cluster
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Gabriela P. Martino, Ingrid M. Quintana, Martín Espariz, Victor S. Blancato, Christian Magni
      Enterococcus is one of the most controversial genera belonging to Lactic Acid Bacteria. Research involving this microorganism reflects its dual behavior as regards its safety. Although it has also been associated to nosocomial infections, natural occurrence of Enterococcus faecium in food contributes to the final quality of cheese. This bacterium is capable of fermenting citrate, which is metabolized to pyruvate and finally derives in the production of the aroma compounds diacetyl, acetoin and 2,3 butanediol. Citrate metabolism was studied in E. faecium but no data about genes related to these pathways have been described. A bioinformatic approach allowed us to differentiate cit − (no citrate metabolism genes) from cit + strains in E. faecium. Furthermore, we could classify them according to genes encoding for the transcriptional regulator, the oxaloacetate decarboxylase and the citrate transporter. Thus we defined type I organization having CitI regulator (DeoR family), CitM cytoplasmic soluble oxaloacetate decarboxylase (Malic Enzyme family) and CitP citrate transporter (2-hydroxy-carboxylate transporter family) and type II organization with CitO regulator (GntR family), OAD membrane oxaloacetate decarboxylase complex (Na+-transport decarboxylase enzyme family) and CitH citrate transporter (CitMHS family). We isolated and identified 17 E. faecium strains from regional cheeses. PCR analyses allowed us to classify them as cit − or cit +. Within the latter classification we could differentiate type I but no type II organization. Remarkably, we came upon E. faecium GM75 strain which carries the insertion sequence IS256, involved in adaptative and evolution processes of bacteria related to Staphylococcus and Enterococcus genera. In this work we describe the differential behavior in citrate transport, metabolism and aroma generation of three strains and we present results that link citrate metabolism and genetic organizations in E. faecium for the first time.


      PubDate: 2015-11-22T20:46:09Z
       
  • Effect of salt types and concentrations on the high-pressure inactivation
           of Listeria monocytogenes in ground chicken
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): S. Balamurugan, Rafath Ahmed, Andrew Chibeu, Anli Gao, Tatiana Koutchma, Phil Strange
      National and international health agencies have recommended a significant reduction in daily intake of sodium by reducing the amount of NaCl in foods, specifically processed meats. However, sodium reduction could increase the risk of survival and growth of spoilage and pathogenic microorganisms on these products. Therefore, alternate processing technologies to improve safety of sodium reduced foods are necessary. This study examined the effects of three different salt types and concentrations on high-pressure inactivation of Listeria monocytogenes in pre-blended ground chicken formulations. Ground chicken formulated with three salt types (NaCl, KCl, CaCl2), at three concentrations (0, 1.5, 2.5%) and inoculated with a four strain cocktail of L. monocytogenes (108 CFUg−1) were subjected to four pressure treatments (0, 100, 300, 600MPa) and two durations (60, 180s) in an experiment with factorial design. Surviving cells were enumerated by plating on Oxford agar and analysed by factorial ANOVA. Pressure treatments at 100 or 300MPa did not significantly (P =0.19–050) reduce L. monocytogenes populations. Neither salt type nor concentration had a significant effect on L. monocytogenes populations at these pressure levels. At 600MPa, salt types, concentrations and duration of pressure treatment all had a significant effect on L. monocytogenes populations. Formulations with increasing concentrations of NaCl or KCl showed significantly lower reduction in L. monocytogenes, while increase in CaCl2 concentration resulted in a significantly higher L. monocytogenes reduction. For instance, increase in NaCl concentration from 0 to 1.5 or 2.5% resulted in a log reduction of 6.16, 2.49 and 1.29, respectively, when exposed to 600MPa for 60s. In the case of CaCl2, increase from 0 to 1.5 or 2.5% resulted in a log reduction of 6.16, 7.28 and 7.47, respectively. These results demonstrate that high-pressure processing is a viable process to improve microbial safety of sodium reduced poultry products.


      PubDate: 2015-11-22T20:46:09Z
       
  • The effect of NaCl reduction in the microbiological quality of cracked
           green table olives of the Maçanilha Algarvia cultivar
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Tânia Mateus, David Santo, Cíntia Saúde, Paula Pires-Cabral, Célia Quintas



      PubDate: 2015-11-22T20:46:09Z
       
  • Detection of Salmonella enterica in pigs at slaughter and comparison with
           human isolates in Italy
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Silvia Bonardi, Irene Alpigiani, Ilaria Bruini, Elena Barilli, Franco Brindani, Marina Morganti, Pierugo Cavallini, Luca Bolzoni, Stefano Pongolini
      In 2013–2014, 201 pigs belonging to 67 batches were tested for Salmonella in their mesenteric lymph nodes (MLN) in one abattoir of Northern Italy. For each batch, faecal material was collected at lairage by swabbing the pen floor for approximately 1600cm2. The aim of this study was to investigate the prevalence of Salmonella in MLN of pigs at slaughter, to assess Salmonella contamination at lairage and to evaluate the effect of lairage duration on its prevalence. Serotyping, XbaI PFGE typing and antimicrobial testing of the isolates were performed. Pig and human Salmonella isolates of the same region of Italy were compared to evaluate possible correlations. Salmonella enterica was isolated from 19.9% of the MLN and 49.3% of the environmental faecal samples. Nine different serovars were identified among 75 S. enterica isolates. In MLN Salmonella Derby was the most common (52.5%), followed by S. enterica 4,[5],12:i:- (17.5%) and Salmonella Rissen (10.0%). In faecal samples S. Derby was prevalent (51.4%), followed by S. enterica 4,[5], 12:i:- (20.0%) and Salmonella Brandenburg (14.3%). Lairage holding varied between 1 and ≥12h (median value: 2.5h). In pigs held for 1–3h, 14.1% were positive for Salmonella in MLN but the prevalence reached 31.8% when they were held for ≥12h. The contamination of MLN was statistically different (p =0.0045) between the two groups, thus confirming the role of long-lasting lairage in Salmonella contamination of pigs. XbaI PFGE typing detected 36 PFGE types. Twenty-three PFGE types were identified among the 40 MLN isolates and 22 PFGE types among the 35 faecal isolates. A total of 11 PFGE types were shared between the MLN of pigs and the lairage environment. Among S. Derby, 6 shared PFGE types between MLN and faeces were found and among S. enterica 4,[5],12:i:- one PFGE type was common between MLN and the faecal samples. Shared profiles between human and swine isolates of S. Derby, S. enterica 4,[5],12:i:-, S. Rissen, Salmonella Manhattan, S. Brandenburg, Salmonella Livingstone, Salmonella London and Salmonella Muenchen were identified. Among S. Derby and S. enterica 4,[5],12:i:- isolates found in pigs, 6/15 profiles (40.0%) and 8/10 (80.0%) were shared with human isolates. High resistance rates to streptomycin (97.3%), sulphonamide compounds (84.0%) and tetracycline (56.0%) were observed. No resistance was detected to ertapenem and meropenem. High proportions of isolates showed intermediate sensitivity to ciprofloxacin (85.3%) and cefotaxime (66.7%). High sensitivity rates were found to chloramphenicol (96.0%) and trimethoprim/sulfamethoxazole (81.3%).


      PubDate: 2015-11-22T20:46:09Z
       
  • Exoproteome analysis reveals higher abundance of proteins linked to
           alkaline stress in persistent Listeria monocytogenes strains
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Kathrin Rychli, Tom Grunert, Luminita Ciolacu, Andreas Zaiser, Ebrahim Razzazi-Fazeli, Stephan Schmitz-Esser, Monika Ehling-Schulz, Martin Wagner
      The foodborne pathogen Listeria monocytogenes, responsible for listeriosis a rare but severe infection disease, can survive in the food processing environment for month or even years. So-called persistent L. monocytogenes strains greatly increase the risk of (re)contamination of food products, and are therefore a great challenge for food safety. However, our understanding of the mechanism underlying persistence is still fragmented. In this study we compared the exoproteome of three persistent strains with the reference strain EGDe under mild stress conditions using 2D differential gel electrophoresis. Principal component analysis including all differentially abundant protein spots showed that the exoproteome of strain EGDe (sequence type (ST) 35) is distinct from that of the persistent strain R479a (ST8) and the two closely related ST121 strains 4423 and 6179. Phylogenetic analyses based on multilocus ST genes showed similar grouping of the strains. Comparing the exoproteome of strain EGDe and the three persistent strains resulted in identification of 22 differentially expressed protein spots corresponding to 16 proteins. Six proteins were significantly increased in the persistent L. monocytogenes exoproteomes, among them proteins involved in alkaline stress response (e.g. the membrane anchored lipoprotein Lmo2637 and the NADPH dehydrogenase NamA). In parallel the persistent strains showed increased survival under alkaline stress, which is often provided during cleaning and disinfection in the food processing environments. In addition, gene expression of the proteins linked to stress response (Lmo2637, NamA, Fhs and QoxA) was higher in the persistent strain not only at 37°C but also at 10°C. Invasion efficiency of EGDe was higher in intestinal epithelial Caco2 and macrophage-like THP1 cells compared to the persistent strains. Concurrently we found higher expression of proteins involved in virulence in EGDe e.g. the actin-assembly-inducing protein ActA and the surface virulence associated protein SvpA. Furthermore proteins involved in cell wall modification, such as the lipoteichonic acid primase LtaP and the N-acetylmuramoyl-l-alanine amidase (Lmo2591) are more abundant in EGDe than in the persistent strains and could indirectly contribute to virulence. In conclusion this study provides information about a set of proteins that could potentially support survival of L. monocytogenes in abiotic niches in food processing environments. Based on these data, a more detailed analysis of the role of the identified proteins under stresses mimicking conditions in food producing environment is essential for further elucidate the mechanism of the phenomenon of persistence of L. monocytogenes.


      PubDate: 2015-11-22T20:46:09Z
       
  • Survival of spoilage bacteria subjected to sequential eugenol and
           temperature treatments
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Yudith Manrique, Sarisa Suriyarak, Monika Gibis, Herbert Schmidt, Jochen Weiss
      Effects of a sequential application of eugenol and temperature on the survival of two model spoilage organisms, Staphylococcus carnosus LTH1502 and Escherichia coli K12 C600, were studied. To assess effects of a “temperature first–antimicrobial later” treatment, cultures were treated with eugenol at 20, 37 and 42°C at the beginning of the incubation period, and after 3h and 8h. To assess effects of an “antimicrobial first–temperature later” treatment, eugenol was added at the beginning of the incubation period at 37°C and temperature was changed to 20 or 42°C after 3 or 8h. Cell numbers were determined in regular intervals during the incubation period using plate counts. Partitioning of eugenol was measured by HPLC, and cell morphology was assessed by electron microscopy. Combined treatments were more effective against the Gram negative E. coli than against S. carnosus. Order of application influenced the effectiveness of treatments, especially at 42°C. There, the temperature first–eugenol later treatment was less effective than other treatments, likely due to temperature-induced adaptation processes occurring in cellular membranes making them more resistant against a later eugenol treatment. Results are of significance in situations where combinations of sublethal stresses are used to build a hurdle concept for food preservation.


      PubDate: 2015-11-22T20:46:09Z
       
  • Effects of fermentation time and low temperature during the production
           process of Thai pickled fish (pla-som) on the viability and infectivity of
           Opisthorchis viverrini metacercariae
    • Abstract: Publication date: 2 February 2016
      Source:International Journal of Food Microbiology, Volume 218
      Author(s): Sudarat Onsurathum, Porntip Pinlaor, Ornuma Haonon, Apisit Chaidee, Lakhanawan Charoensuk, Kitti Intuyod, Thidarut Boonmars, Porntip Laummaunwai, Somchai Pinlaor
      Contamination of a popular fermented fish dish, pla-som, by Opisthorchis viverrini metacercariae (OVMC) is a possible cause of carcinogenic liver fluke infection in Thailand. Affected individuals are at risk of bile duct cancer, which is a major health problem for people in the Greater Mekong Subregion. In order to investigate concerns about food safety, we studied the effects of fermentation time and low temperature on the viability and infectivity of OVMC during the pla-som production process. Pla-som was prepared at room temperature for up to 1week in duplicate experiments using cyprinid freshwater fish obtained from an O. viverrini-endemic area. OVMC were then isolated and identified under a stereomicroscope. Complete and viable OVMC were found on days 1–4 of fermentation, while their morphology was degenerated thereafter. After OVMC were fed to hamsters, the percentage of the worm recovery after 1 to 2months of infection was 52%, 44.7%, 11.3% and 1% for days 1, 2, 3 and 4, respectively. In order to measure the effect of low temperature on OVMC, fish were kept in a refrigerator (4°C) for up to five days and then subsequently fermented for three days. In fish stored in a refrigerator for 1 and 2days, viable OVMC were clearly observed and were able to infect hamsters, a worm-recovery percentage of 3.3% and 12.7%, respectively. By contrast, in pla-som prepared from fish stored for 3 to 5days, OVMC were degenerated and could not infect the host. In conclusion, pla-som fermentation for more than four days and refrigerating fish for three days before pla-som processing can prevent O. viverrini infection. This study may increase awareness of fermented-fish dish preparation to prevent liver fluke infection.


      PubDate: 2015-11-18T13:46:17Z
       
 
 
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