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MICROBIOLOGY (210 journals)                  1 2 3     

Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 6)
Addiction Genetics     Open Access   (Followers: 3)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 13)
Advances in Microbiology     Open Access   (Followers: 14)
Advances in Molecular Imaging     Open Access   (Followers: 3)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Microbiology Research     Open Access   (Followers: 1)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 12)
American Journal of Microbiological Research     Open Access  
American Journal of Microbiology     Open Access   (Followers: 14)
American Journal of Molecular Biology     Open Access   (Followers: 3)
American Journal of Stem Cell Research     Open Access   (Followers: 1)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 5)
Annals of Microbiology     Hybrid Journal   (Followers: 7)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 21)
Antimicrobial Agents and Chemotherapy     Full-text available via subscription   (Followers: 14)
Applied and Environmental Microbiology     Full-text available via subscription   (Followers: 23)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 7)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 23)
Archives of Microbiology     Hybrid Journal   (Followers: 3)
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   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Research     Open Access   (Followers: 3)
BioMolecular Concepts     Full-text available via subscription   (Followers: 2)
Biomolecules     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 6)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases & Medical Microbiology     Hybrid Journal   (Followers: 1)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 3)
Cell Biology : Research & Therapy     Partially Free  
Cell Host & Microbe     Full-text available via subscription   (Followers: 6)
Cell Medicine     Open Access  
Cell Regeneration     Open Access  
Cell Stem Cell     Full-text available via subscription   (Followers: 17)
Cells     Open Access  
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 8)
Cellular Microbiology     Hybrid Journal   (Followers: 4)
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: 13)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 3)
Clinical Microbiology Reviews     Full-text available via subscription   (Followers: 10)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 7)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Continental Journal of Microbiology     Open Access   (Followers: 3)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 5)
Current Issues in Molecular Biology     Open Access  
Current Microbiology     Hybrid Journal   (Followers: 5)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 14)
Current Tissue Engineering     Hybrid Journal   (Followers: 1)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 3)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 3)
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: 1)
Environmental Microbiology     Hybrid Journal   (Followers: 7)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 3)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 5)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 1)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 10)
European Journal of Microbiology and Immunology     Open Access   (Followers: 6)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 1)
Fems Immunology & Medical Microbiology     Hybrid Journal   (Followers: 6)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 6)
Fems Microbiology Letters     Hybrid Journal   (Followers: 13)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 16)
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 11)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 1)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 2)
Frontiers in Cellular Neuroscience     Open Access  
Frontiers in Microbiology     Open Access   (Followers: 5)
Frontiers in Molecular Neuroscience     Open Access  
Future Microbiology     Full-text available via subscription   (Followers: 2)
Future Virology     Full-text available via subscription   (Followers: 3)
Gene Expression     Full-text available via subscription  
Genetica si Biologie Moleculara     Open Access   (Followers: 1)
Genetics and Molecular Research     Open Access   (Followers: 2)
Geomicrobiology Journal     Hybrid Journal   (Followers: 1)
Gut Microbes     Full-text available via subscription   (Followers: 1)
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)
International Arabic Journal of Antimicrobial Agents     Open Access   (Followers: 4)
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 1)
International Journal of Bacteriology     Open Access  
International Journal of Bioassays     Open Access   (Followers: 5)
International Journal of Biotechnology and Molecular Biology Research     Open Access  
International Journal of Food Microbiology     Hybrid Journal   (Followers: 11)
International Journal of Infection and Microbiology     Open Access   (Followers: 1)
International Journal of Medical Microbiology     Hybrid Journal   (Followers: 5)
International Journal of Systematic and Evolutionary Microbiology     Full-text available via subscription   (Followers: 2)
International Microbiology     Open Access   (Followers: 2)
Invertebrate Immunity     Open Access  

        1 2 3     

Journal Cover International Journal of Food Microbiology
   Journal TOC RSS feeds Export to Zotero [13 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0168-1605
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.386]   [H-I: 108]
  • Shedding of Salmonella in single age caged commercial layer flock at an
           early stage of lay
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Vaibhav C. Gole , Charles G.B. Caraguel , Margaret Sexton , Chelsea Fowler , Kapil K. Chousalkar
      The shedding of Salmonella in a single age commercial egg layer flock was investigated at the onset of lay (18weeks) followed by two longitudinal samplings at 24 and 30weeks. At the age of 18weeks, when the first sampling was performed, the prevalence of Salmonella in faeces was 82.14% whereas all egg belt and dust samples were Salmonella positive by culture method. In later samplings, at the age of 24 and 30weeks, the prevalence of Salmonella in faeces was significantly reduced (p<0.001) to 38.88% and 12.95% respectively, however all egg belt and dust samples remained positive by culture method. The prevalence of Salmonella in faeces collected from the low tier cages was significantly higher (p=0.009) as compared with samples from the high tier cages. In all types of samples processed by culture method, S. Mbandaka was the most frequently (54.40%) isolated serovar followed by S. Worthington (37.60%), S. Anatum (0.8%), and S. Infantis (0.8%). All samples were also tested by real-time PCR method. The observed agreement between culture method and real-time PCR in detecting Salmonella-positive dust and egg belt samples was 100%. There was almost perfect agreement (observed agreement=99.21%) for the detection of Salmonella-positive eggshells. Observed agreement between culture method and real-time PCR for detecting Salmonella-positive shoe cover and faecal samples was, however, moderate (80%) and low (54.27%) respectively. Real-time PCR results showed that there was a significant increase in the load of Salmonella on egg belt, dust and shoe cover samples at the 24 and 30weeks of lay as compared to the 18weeks of lay. Real-time PCR provided a more rapid and reliable method of detection of Salmonella on all dry sample types whereas the traditional culture method proved much more reliable when trying to detect Salmonella in wet faecal samples.


      PubDate: 2014-08-15T17:50:30Z
       
  • Editorial Board
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188




      PubDate: 2014-08-15T17:50:30Z
       
  • Safety and technological characterization of Staphylococcus equorum
           isolates from jeotgal, a Korean high-salt-fermented seafood, for starter
           development
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Do-Won Jeong , Seulhwa Han , Jong-Hoon Lee
      To select starters for jeotgal, a traditional Korean high-salt-fermented seafood, the safety and technological properties of its predominant bacteria isolates, which were identified as Staphylococcus equorum, were assessed. Among the 185 S. equorum isolates from jeotgal, 126 ampicillin-sensitive strains were subjected to assessments for antibiotic susceptibility and safety hazards. Sixty-six out of the 126 S. equorum strains exhibited phenotypic resistances to at least one antibiotic, and their prevailing resistances were to penicillin G (34.1%), erythromycin (9.5%) and trimethoprim (9.5%). Twenty-four S. equorum strains expressed resistance to at least two antibiotics. The lnuA for lincomycin (four strains) and pbp for β-lactam (three strains) were amplified by PCR. α-Hemolytic activity was not detected from the 126 strains, and 87 strains presented δ-hemolytic activity. Among the 87 strains, three strains exhibited β-hemolytic activity. Thirty-seven strains formed a biofilm. A hemolysin gene homologous to that of Staphylococcus epidermidis was amplified from an S. equorum strain with β-hemolytic activity by PCR; however, no PCR product homologous to the previously known staphylococcal enterotoxin genes was amplified. Thirty-nine S. equorum strains cleared all of the tested safety hazards and were adopted for technological property assessments. Among these strains, 16 strains exhibited protease, lipase and nitrate reductase activities, and seven strains did not produce four types of biogenic amines. Five biogenic amine non-producers exhibited three enzyme activities. Most of the strains could grow on the agar with 20% NaCl, and 13 strains maintained growth at the 25% NaCl condition. S. equorum KS1039, which is the most applicable strain that covers the safety and technological requirements for jeotgal, can grow at the 25% NaCl condition. Through this research study, we reconfirmed the necessity of characterization in the functionality and safety of S. equorum for starter development because all of the tested phenotypic characteristics were expressed in strain-specific manners.


      PubDate: 2014-08-15T17:50:30Z
       
  • Corrigendum to “Identification and quantification of Lactobacillus
           casei strain Shirota in human feces with strain-specific primers derived
           from randomly amplified polymorphic DNA” [Int. J. Food Microbiol.
           126 (2008) 210–215]
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Junji Fujimoto , Takahiro Matsuki , Masae Sasamoto , Yasuaki Tomii , Koichi Watanabe



      PubDate: 2014-08-15T17:50:30Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188




      PubDate: 2014-08-15T17:50:30Z
       
  • Occurrence of the three major Vibrio species pathogenic for human in
           seafood products consumed in France using real-time PCR
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Annick Robert-Pillot , Stéphanie Copin , Charlotte Himber , Mélanie Gay , Marie-Laure Quilici
      Vibrio spp. have emerged as a serious threat to human health worldwide. Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus are of particular concern as they have been linked to gastrointestinal infections and septicemia associated with the consumption of raw or undercooked seafood. We developed hydrolysis probe-based real-time PCR systems with an internal amplification control for the detection of these species. We applied these systems to a total of 167 fresh or frozen crustacean, fish and shellfish samples consumed in France. Of them, 34.7% (n =58) were positive for Vibrio. V. parahaemolyticus was the most common, in 31.1% of samples, followed by V. vulnificus in 12.6% and V. cholerae in 0.6%. Furthermore, V. parahaemolyticus and V. vulnificus were present simultaneously in 9.6% of samples. Virulence genes (tdh and trh sequences) were present in 25% of the V. parahaemolyticus-positive samples. The V. cholerae strain detected was non toxigenic. The densities of V. parahaemolyticus and V. cholerae ranged from <102 to 104 bacteria/g of seafood. All samples positive for V. vulnificus displayed low-level contamination with fewer than 102 bacteria/g. Our findings indicate that seafood consumption presents a potential risk to human health in France and highlight the importance of tools for a preventive consumer protection policy.


      PubDate: 2014-08-15T17:50:30Z
       
  • Development of a selective agar plate for the detection of Campylobacter
           spp. in fresh produce
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Jin-Hee Yoo , Na-Young Choi , Young-Min Bae , Jung-Su Lee , Sun-Young Lee
      This study was conducted to develop a selective medium for the detection of Campylobacter spp. in fresh produce. Campylobacter spp. (n=4), non-Campylobacter (showing positive results on Campylobacter selective agar) strains (n=49) isolated from fresh produce, indicator bacteria (n=13), and spoilage bacteria isolated from fresh produce (n=15) were plated on four Campylobacter selective media. Bolton agar and modified charcoal cefoperazone deoxycholate agar (mCCDA) exhibited higher sensitivity for Campylobacter spp. than did Preston agar and Hunt agar, although certain non-Campylobacter strains isolated from fresh produce by using a selective agar isolation method, were still able to grow on Bolton agar and mCCDA. To inhibit the growth of non-Campylobacter strains, Bolton agar and mCCDA were supplemented with 5 antibiotics (rifampicin, polymyxin B, sodium metabisulfite, sodium pyruvate, ferrous sulfate) and the growth of Campylobacter spp. (n=7) and non-Campylobacter strains (n=44) was evaluated. Although Bolton agar supplemented with rifampicin (BR agar) exhibited a higher selectivity for Campylobacter spp. than did mCCDA supplemented with antibiotics, certain non-Campylobacter strains were still able to grow on BR agar (18.8%). When BR agar with various concentrations of sulfamethoxazole–trimethoprim were tested with Campylobacter spp. (n=8) and non-Campylobacter (n=7), sulfamethoxazole–trimethoprim was inhibitory against 3 of 7 non-Campylobacter strains. Finally, we validated the use of BR agar containing 50mg/L sulfamethoxazole (BRS agar) or 0.5mg/L ciprofloxacin (BRCS agar) and other selective agars for the detection of Campylobacter spp. in chicken and fresh produce. All chicken samples were positive for Campylobacter spp. when tested on mCCDA, BR agar, and BRS agar. In fresh produce samples, BRS agar exhibited the highest selectivity for Campylobacter spp., demonstrating its suitability for the detection of Campylobacter spp. in fresh produce.


      PubDate: 2014-08-15T17:50:30Z
       
  • Biocontrol activity of four non- and low-fermenting yeast strains against
           Aspergillus carbonarius and their ability to remove ochratoxin A from
           grape juice
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Stefano Fiori , Pietro Paolo Urgeghe , Walid Hammami , Salvatorico Razzu , Samir Jaoua , Quirico Migheli
      Aspergillus spp. infection of grape may lead to ochratoxin A (OTA) contamination in processed beverages such as wine and grape juice. The aim of the current study was to evaluate the biocontrol potential of two non-fermenting (Cyberlindnera jadinii 273 and Candida friedrichii 778) and two low-fermenting (Candida intermedia 235 and Lachancea thermotolerans 751) yeast strains against the pathogenic fungus and OTA-producer Aspergillus carbonarius, and their ability to remove OTA from grape juice. Two strains, 235 and 751, showed a significant ability to inhibit A. carbonarius both on grape berries and in in vitro experiments. Neither their filtrate nor their autoclaved filtrate culture broth was able to prevent consistently pathogen growth. Volatile organic compounds (VOCs) produced by all four selected yeasts were likely able to consistently prevent pathogen sporulation in vitro. VOCs produced by the non-fermenting strain 778 also significantly reduced A. carbonarius vegetative growth. Three yeast strains (235, 751, and 778) efficiently adsorbed artificially spiked OTA from grape juice, while autoclaving treatment improved OTA adsorption capacity by all the four tested strains. Biological control of A. carbonarius and OTA-decontamination using yeast is proposed as an approach to meet the Islamic dietary laws concerning the absence of alcohol in halal beverages.


      PubDate: 2014-08-12T17:38:59Z
       
  • Distribution of aflatoxigenic Aspergillus section Flavi in commercial
           poultry feed in Nigeria
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): C.N. Ezekiel , J. Atehnkeng , A.C. Odebode , R. Bandyopadhyay
      The distribution and aflatoxigenicity of Aspergillus section Flavi isolates in 58 commercial poultry feed samples obtained from 17 states in five agro-ecological zones (AEZs) in Nigeria were determined in order to assess the safety of the feeds with respect to aflatoxin-producing fungi. Correlation was also performed for incidence of species, aflatoxin-producing ability of isolates in vitro, and aflatoxin (AFB1) concentrations in the feed. A total of 1006 Aspergillus section Flavi isolates were obtained from 87.9% of the feed samples and identified as Aspergillus flavus, unnamed taxon SBG, Aspergillus parasiticus and Aspergillus tamarii. A. flavus was the most prevalent (91.8%) of the isolates obtained from the feed in the AEZs while A. parasiticus had the lowest incidence (0.1%) and was isolated only from a layer mash sample collected from the DS zone. About 29% of the Aspergillus isolates produced aflatoxins in maize grains at concentrations up to 440,500μg/kg B and 341,000μg/kgG aflatoxins. The incidence of toxigenic isolates was highest (44.4%) in chick mash and lowest (19.9%) in grower mash. The population of A. flavus in the feed had positive (r =0.50) but non significant (p >0.05) correlations with proportion of toxigenic isolates obtained from the feed while SBG had significant (p <0.001) positive (r =0.99) influence on AFB1 concentrations in the feed. Poultry feed in Nigerian markets are therefore highly contaminated with aflatoxigenic Aspergillus species and consequently, aflatoxins. This is a potential threat to the poultry industry and requires urgent intervention.


      PubDate: 2014-08-12T17:38:59Z
       
  • Sequencing, physical organization and kinetic expression of the patulin
           biosynthetic gene cluster from Penicillium expansum
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Joanna Tannous , Rhoda El Khoury , Selma P. Snini , Yannick Lippi , André El Khoury , Ali Atoui , Roger Lteif , Isabelle P. Oswald , Olivier Puel
      Patulin is a polyketide-derived mycotoxin produced by numerous filamentous fungi. Among them, Penicillium expansum is by far the most problematic species. This fungus is a destructive phytopathogen capable of growing on fruit, provoking the blue mold decay of apples and producing significant amounts of patulin. The biosynthetic pathway of this mycotoxin is chemically well-characterized, but its genetic bases remain largely unknown with only few characterized genes in less economic relevant species. The present study consisted of the identification and positional organization of the patulin gene cluster in P. expansum strain NRRL 35695. Several amplification reactions were performed with degenerative primers that were designed based on sequences from the orthologous genes available in other species. An improved genome Walking approach was used in order to sequence the remaining adjacent genes of the cluster. RACE-PCR was also carried out from mRNAs to determine the start and stop codons of the coding sequences. The patulin gene cluster in P. expansum consists of 15 genes in the following order: patH, patG, patF, patE, patD, patC, patB, patA, patM, patN, patO, patL, patI, patJ, and patK. These genes share 60–70% of identity with orthologous genes grouped differently, within a putative patulin cluster described in a non-producing strain of Aspergillus clavatus. The kinetics of patulin cluster genes expression was studied under patulin-permissive conditions (natural apple-based medium) and patulin-restrictive conditions (Eagle's minimal essential medium), and demonstrated a significant association between gene expression and patulin production. In conclusion, the sequence of the patulin cluster in P. expansum constitutes a key step for a better understanding of the mechanisms leading to patulin production in this fungus. It will allow the role of each gene to be elucidated, and help to define strategies to reduce patulin production in apple-based products.


      PubDate: 2014-08-12T17:38:59Z
       
  • Characterization of integrons and resistance genes in multidrug-resistant
           Salmonella enterica isolated from meat and dairy products in Egypt
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Ashraf M. Ahmed , Toshi Shimamoto , Tadashi Shimamoto
      Foodborne pathogens are a leading cause of illness and death, especially in developing countries. The problem is exacerbated if bacteria attain multidrug resistance. Little is currently known about the extent of antibiotic resistance in foodborne pathogens and the molecular mechanisms underlying this resistance in Africa. Therefore, the current study was carried out to characterize, at the molecular level, the mechanism of multidrug resistance in Salmonella enterica isolated from 1600 food samples (800 meat products and 800 dairy products) collected from different street venders, butchers, retail markets and slaughterhouses in Egypt. Forty-seven out of 69 isolates (68.1%) showed multidrug resistance phenotypes to at least three classes of antimicrobials. The incidence of multidrug-resistant isolates was higher in meat products (37, 69.8%) than in dairy products (10, 62.5%). The multidrug-resistant serovars included, S. enterica serovar Typhimurium (24 isolates, 34.8%), S. enterica serovar Enteritidis, (15 isolates, 21.8%), S. enterica serovar Infantis (7 isolates, 10.1%) and S. enterica non-typable serovar (1 isolate, 1.4%). The highest resistance was to ampicillin (95.7%), then to kanamycin (93.6%), spectinomycin (93.6%), streptomycin (91.5%) and sulfamethoxazole/trimethoprim (91.5%). PCR and DNA sequencing were used to screen and characterize integrons and antibiotic resistance genes and 39.1% and 8.7% of isolates were positive for class 1 and class 2 integrons, respectively. β-lactamase-encoding genes were identified in 75.4% of isolates and plasmid-mediated quinolone resistance genes were identified in 27.5% of isolates. Finally, the florphenicol resistance gene, floR, was identified in 18.8% of isolates. PCR screening identified S. enterica serovar Typhimurium DT104 in both meat and dairy products. This is the first study to report many of these resistance genes in dairy products. This study highlights the high incidence of multidrug-resistant S. enterica in meat and dairy products in Egypt, with the possibility of their transfer to humans leading to therapeutic failure. Therefore, the overuse of antibiotics in animals should be drastically reduced in developing countries.


      PubDate: 2014-08-12T17:38:59Z
       
  • Characterization of an unusual Salmonella phage type DT7a and report of a
           foodborne outbreak of salmonellosis
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): A.A. Lettini , C. Saccardin , E. Ramon , A. Longo , E. Cortini , M.C. Dalla Pozza , L. Barco , B. Guerra , I. Luzzi , A. Ricci
      Salmonella enterica subsp. enterica serovar 4,[5],12,i:− is a monophasic variant of Salmonella Typhimurium and its occurrence has markedly increased in several European countries in the last ten years. In June 2011, an outbreak of Salmonella 4,[5],12,i:− was reported among attendees of a wedding reception in the North-East of Italy. The source of this outbreak was identified as a cooked pork product served during the wedding reception. All Salmonella isolates from humans and the contaminated pork products were identified as Salmonella 4,[5],12,i:− and phage typed as DT7a. Afterwards, the farm where the pigs were raised was identified and sampled, and Salmonella Typhimurium was isolated from swine fecal samples. Despite the difference in serovar, these Salmonella Typhimurium isolates were also phage typed as DT7a. In the present study, Salmonella isolates from animals, humans and pork products during the outbreak investigation were subtyped by pulsed-field gel electrophoresis (PFGE), Multiple-Locus Variable number tandem repeats Analysis (MLVA), and resistance patterns, aiming to identify the most suitable subtyping methods to characterize isolates associated with this outbreak. In addition, a collection of epidemiologically unrelated strains of Salmonella 4,[5],12,i:− and Salmonella Typhimurium sharing the same phage type (DT7a) was similarly characterized in order to investigate their genetic relationship. This study provides a first snapshot of a rare Salmonella phage type, DT7a, associated with both Salmonella 4,[5],12,i:− and Salmonella Typhimurium. Moreover, the study demonstrated that in this specific context MLVA could be a reliable tool to support outbreak investigations as well as to assess the genetic relatedness among Salmonella isolates.


      PubDate: 2014-08-12T17:38:59Z
       
  • Comparison of identification systems for psychrotrophic bacteria isolated
           from raw bovine milk
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Nuwan R. Vithanage , Thomas R. Yeager , Snehal R. Jadhav , Enzo A. Palombo , Nivedita Datta
      Psychrotrophic bacteria in raw milk produce heat-resistant extracellular proteases, resulting in spoilage and shelf-life reduction of ultrahigh temperature treated milk and milk products. Controlling of these spoilage microbes requires rapid and reliable identification systems for screening of raw milk. This study aimed to compare commercial bacterial identification systems with a genetic method (considered as the ‘gold standard’ method) for the identification of heat-resistant protease producing bacteria in raw milk. Five bacterial identification systems were compared based on typability, discrimination power (i.e. Simpson's Index of Diversity), reproducibility and speed of analysis. The accuracy of 16S rRNA gene sequencing, Biolog, MALDI-TOF MS, API, and Microbact for the identification of Gram negative bacilli at the species level was 100.0%, 86.8%, 63.2%, 60.5% and 57.9%, respectively. The Gram positive bacilli were identified by 16S rRNA gene sequencing, Biolog, MALDI-TOF MS, and API with accuracies at the species level of 100.0%, 85.0%, 95.0% and 90.0%, respectively. The 16S rRNA gene sequencing and phylogenetic analysis discriminated Pseudomonas fluorescens, Pseudomonas syringae, Hafnia alvei, Bacillus cereus, Bacillus pumilus and Bacillus licheniformis to the subspecies level. The Simpson's Index of Diversity scores were 0.966, 0.711, 0.496, 0.472, and 0.140, for 16S rRNA gene sequencing, Biolog, MALDI-TOF MS, API and Microbact, respectively. Limited reference profiles in the databases of Biolog, MALDI-TOF MS, API and Microbact systems reduced their accuracy in bacterial identification, compared to 16S rRNA gene sequencing. The rapidity of each assay is in the following order; MALDI-TOF MS>16S rRNA gene sequencing>Biolog>Microbact>API. The reproducibility of the assays is in the order of 16S rRNA gene sequencing>API>Microbact>MALDI-TOF MS>Biolog. Thus, 16S rRNA gene sequencing appears to be the most reliable and robust system for the identification of dairy spoilage bacteria. The Biolog system is suitable for the identification of Gram negative spoilage bacteria, while MALDI-TOF MS and API systems are suitable for the identification of Gram positive spoilage bacteria isolated from raw milk. The commercial systems used in this study have been developed and extensively used for the identification of clinical microbes but only a limited number of studies used those systems to identify the environmental microorganisms that often contaminate raw milk. Therefore, comparison of those systems for the identification of spoilage microbes in raw milk would provide better understanding of their suitability for routine dairy microbiology and more extensive dairy research.


      PubDate: 2014-08-12T17:38:59Z
       
  • Buckwheat achenes antioxidant profile modulates Aspergillus flavus growth
           and aflatoxin production
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): G. Chitarrini , C. Nobili , F. Pinzari , A. Antonini , P. De Rossi , A. Del Fiore , S. Procacci , V. Tolaini , V. Scala , M. Scarpari , M. Reverberi
      Buckwheat (Fagopyrum spp.) is a “pseudo-cereal” of great interest in the production of healthy foods since its flour, derived from achenes, is enriched with bioactive compounds and, due to the absence of gluten, may be used in composition of celiac diets. Amongst buckwheat species, F. tataricum achenes possess a larger amount of the antioxidant flavenol rutin than the common buckwheat F. esculentum. Ongoing climate change may favor plant susceptibility to the attack by pathogenic, often mycotoxigenic, fungi with consequent increase of mycotoxins in previously unexploited feeds and foodstuffs. In particular, Aspergillus flavus, under suitable environmental conditions such as those currently occurring in Italy, may produce aflatoxin B1 (AFB1), the most carcinogenic compound of fungal origin which is classified by IARC as Category 1. In this study, the viable achenes of two buckwheat species, F. tataricum (var. Golden) and F. esculentum (var. Aelita) were inoculated with an AFB1-producing A. flavus NRRL 3357 to analyze their relative performances against fungal invasion and toxin contamination. Notably, we sought the existence of a correlation between the amount of tocols/flavonols in the achenes of buckwheat, infected and non-infected with A. flavus, and to analyze the ability of the pathogen to grow and produce toxin during achene infection. Results suggest that achenes of F. tataricum, the best producer of antioxidant compounds in this study, are less susceptible to A. flavus infection and consequently, but not proportionally, to mycotoxin contamination compared with F. esculentum. Moreover, rutin-derived quercetin appears to be more efficient in inhibiting aflatoxin biosynthesis than the parent compound.


      PubDate: 2014-08-12T17:38:59Z
       
  • The impact of water and temperature interactions on lag phase, growth and
           potential ochratoxin A production by two new species, Aspergillus
           aculeatinus and A. sclerotiicarbonarius, on a green coffee-based medium
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Asya Akbar , Naresh Magan
      Two new species of Aspergillus (A. aculeatinus, A. sclerotiicarbonarius) were previously isolated from coffee in Thailand. The objective of this study was to examine the effect of interacting environmental factors of water availability (water activity, a w) and temperature on lag phases prior to growth, growth and potential for ochratoxin A (OTA) production by three strains of each species on a green coffee-based medium for the first time. This showed that overall the growth of the three strains of each species was similar over the 20–37°C and 0.85–0.99 a w ranges. The lag phase prior to growth was <1day at 0.95–0.98 a w and 25–37°C and increased to 2–3 days at marginal temperatures and a w levels. The growth of strains of the uniseriate species A. aculeatinus was optimum at 0.98 a w and 30–35°C. For the biseriate A. sclerotiicarbonarius strains this was 0.99 a w and 30°C. This species was not able to grow at 37°C. None of the strains of the two species grew at 0.85 a w, regardless of temperature. Integrated profiles based on the data from three strains of each species have been developed to show the optimum, maximum and marginal conditions of interacting aw and temperature conditions for growth. None of the strains produced OTA on a green coffee-based medium. This information is important as these species are part of the mycobiota of coffee and may influence OTA contamination by other ochratoxigenic species during coffee processing.


      PubDate: 2014-08-07T17:03:33Z
       
  • Quantitative effects of in-line operations on Campylobacter and
           Escherichia coli through two Australian broiler processing plants
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Lesley L. Duffy , Patrick J. Blackall , Rowland N. Cobbold , Narelle Fegan
      Campylobacter is an important food borne pathogen, mainly associated with poultry. A lack of through-chain quantitative Campylobacter data has been highlighted within quantitative risk assessments. The aim of this study was to quantitatively and qualitatively measure Campylobacter and Escherichia coli concentration on chicken carcasses through poultry slaughter. Chickens (n=240) were sampled from each of four flocks along the processing chain, before scald, after scald, before chill, after chill, after packaging and from individual caeca. The overall prevalence of Campylobacter after packaging was 83% with a median concentration of 0.8log10 CFU/mL. The processing points of scalding and chilling had significant mean reductions of both Campylobacter (1.8 and 2.9log10 CFU/carcase) and E. coli (1.3 and 2.5log10 CFU/carcase). The concentration of E. coli and Campylobacter was significantly correlated throughout processing indicating that E. coli may be a useful indicator organism for reductions in Campylobacter concentration. The carriage of species varied between flocks, with two flocks dominated by Campylobacter coli and two flocks dominated by Campylobacter jejuni. Current processing practices can lead to significant reductions in the concentration of Campylobacter on carcasses. Further understanding of the variable effect of processing on Campylobacter and the survival of specific genotypes may enable more targeted interventions to reduce the concentration of this poultry associated pathogen.


      PubDate: 2014-08-07T17:03:33Z
       
  • Effect of lauric arginate, nisin Z, and a combination against several
           food-related bacteria
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Rinrada Pattanayaiying , Aran H-Kittikun , Catherine N. Cutter
      The effects of lauric arginate (LAE) and nisin Z, alone or in combination, on cell damage were investigated against Escherichia coli O157:H7, Listeria monocytogenes and Brochothrix thermosphacta, by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, efflux of potassium and phosphate ions, and growth inhibition. A combination of LAE with nisin Z caused severe and dramatic changes in the cytoplasmic membrane and cell lysis of both Gram-positive and Gram-negative bacteria. The combination treatment also caused significant potassium and phosphate ion leakage of E. coli O157:H7, L. monocytogenes and B. thermosphacta, when compared with other treatments: 16.62±1.05, 50.35±0.81 and 45.47±1.15mg/L of potassium ion and 122.66±8.81, 97.96±3.31 and 26.47±13.97mg/L of phosphate ion after treatment for 6h, respectively. Bacteria were reduced by approximately 7log10 CFU/mL within the first hour of treatment and then cells were unable to grow for the remainder of the experiment. Treatment with LAE alone resulted in changes in cellular morphology, coagulation of the cytoplasm, and low level leakage of potassium and phosphate ions in all bacteria tested. Treatment of L. monocytogenes and B. thermosphacta with nisin Z (320AU/mL of final concentration) resulted in the formation of membrane channels and leakage of potassium and phosphate ions at rather high levels; but the bacteriocin was not effective against E. coli O157:H7. LAE or nisin Z reduced growth of both L. monocytogenes and B. thermosphacta by approximately 7log10 CFU/mL. Conversely, E. coli O157:H7 was not inhibited by treatments with nisin Z, but decreased by approximately 4.45log10 CFU/mL after treatment with LAE. These findings provide additional information on the mode of action of these compounds on bacterial populations.


      PubDate: 2014-08-07T17:03:33Z
       
  • Colonization of the meat extracellular matrix proteins by O157 and
           non-O157 enterohemorrhagic Escherichia coli
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Caroline Chagnot , Nelly Caccia , Estelle Loukiadis , Sarah Ganet , Alexandra Durand , Yolande Bertin , Régine Talon , Thierry Astruc , Mickaël Desvaux
      Enterohemorrhagic Escherichia coli (EHEC) are anthropozoonotic agents that range third among food-borne pathogens respective to their incidence and dangerousness in the European Union. EHEC are Shiga-toxin producing E. coli (STEC) responsible for foodborne poisoning mainly incriminated to the consumption of contaminated beef meat. Among the hundreds of STEC serotypes identified, EHEC mainly belong to O157:H7 but non-O157 can represent 20 to 70% of EHEC infections per year. Seven of those serogroups are especially of high-risk for human health, i.e. O26, O45, O103, O111, O121, O145 and O104. While meat can be contaminated all along the food processing chain, EHEC contamination essentially occurs at the dehiding stage of slaughtering. Investigating bacterial colonization to the skeletal-muscle extracellular matrix (ECM) proteins, it appeared that environmental factors influenced specific and non-specific bacterial adhesion of O157 and non-O157 EHEC as well as biofilm formation. Importantly, mechanical treatment (i.e. shaking, centrifugation, pipetting and vortexing) inhibited and biased the results of bacterial adhesion assay. Besides stressing the importance of the protocol to investigate bacterial adhesion to ECM proteins, this study demonstrated that the colonization abilities to ECM proteins vary among EHEC serogroups and should ultimately be taken into consideration to evaluate the risk of contamination for different types of food matrices.


      PubDate: 2014-08-04T16:53:40Z
       
  • Characterization of novel killer toxins secreted by wine-related
           non-Saccharomyces yeasts and their action on Brettanomyces spp.
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Ngwekazi N. Mehlomakulu , Mathabatha E. Setati , Benoit Divol
      Wine spoilage associated with Brettanomyces bruxellensis is a major concern for winemakers. An effective and reliable method to control the proliferation of this yeast is therefore of utmost importance. To achieve this purpose, sulphur dioxide (SO2) is commonly employed but the efficiency of this chemical compound is subject to wine composition and it can elicit allergic reactions in some consumers. Biological alternatives are therefore actively sought. The current study focused on identifying and characterizing killer toxins which are antimicrobial compounds that show potential in inhibiting B. bruxellensis in wine. Two killer toxins, CpKT1 and CpKT2, from the wine isolated yeast Candida pyralidae were identified and partially characterized. The two proteins had a molecular mass above 50kDa and exhibited killer activity against several B. bruxellensis strains especially in grape juice. They were active and stable at pH3.5–4.5, and temperatures between 15 and 25°C which are compatible with winemaking conditions. Furthermore, the activity of these killer toxins was not affected by the ethanol and sugar concentrations typically found in grape juice and wine. In addition, these killer toxins inhibited neither the Saccharomyces cerevisiae nor the lactic acid bacteria strains tested. These preliminary results indicated that the application of these toxins will have no effect on the main microbial agents that drive alcoholic and malolactic fermentations and further highlight the potential of using these toxins as agents to control the development of B. bruxellensis in grape juice or wine.


      PubDate: 2014-08-04T16:53:40Z
       
  • Comparison of species composition and fumonisin production in Aspergillus
           section Nigri populations in maize kernels from USA and Italy
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Antonia Susca , Antonio Moretti , Gaetano Stea , Alessandra Villani , Miriam Haidukowski , Antonio Logrieco , Gary Munkvold
      Fumonisin contamination of maize is considered a serious problem in most maize-growing regions of the world, due to the widespread occurrence of these mycotoxins and their association with toxicosis in livestock and humans. Fumonisins are produced primarily by species of Fusarium that are common in maize grain, but also by some species of Aspergillus sect. Nigri, which can also occur on maize kernels as opportunistic pathogens. Understanding the origin of fumonisin contamination in maize is a key component in developing effective management strategies. Although some fungi in Aspergillus sect. Nigri are known to produce fumonisins, little is known about the species which are common in maize and whether they make a measurable contribution to fumonisin contamination of maize grain. In this work, we evaluated populations of Aspergillus sect. Nigri isolated from maize in USA and Italy, focusing on analysis of housekeeping genes, the fum8 gene and in vitro capability of producing fumonisins. DNA sequencing was used to identify Aspergillus strains belonging to sect. Nigri, in order to compare species composition between the two populations, which might influence specific mycotoxicological risks. Combined beta-tubulin/calmodulin sequences were used to genetically characterize 300 strains (199 from Italy and 101 from USA) which grouped into 4 clades: Aspergillus welwitschiae (syn. Aspergillus awamori, 14.7%), Aspergillus tubingensis (37.0%) and Aspergillus niger group 1 (6.7%) and group 2 (41.3%). Only one strain was identified as Aspergillus carbonarius. Species composition differed between the two populations; A. niger predominated among the USA isolates (69%), but comprised a smaller percentage (38%) of Italian isolates. Conversely, A. tubingensis and A. welwitschiae occurred at higher frequencies in the Italian population (42% and 20%, respectively) than in the USA population (27% and 5%). The evaluation of FB2 production on CY20S agar revealed 118 FB2 producing and 84 non-producing strains distributed among the clades: A. welwitschiae, A. niger group 1 and A. niger group 2, confirming the potential of Aspergillus sect. Nigri species to contribute to total fumonisin contamination of maize. A higher percentage of A. niger isolates (72.0%) produced FB2 compared to A. welwitschiae (36.6%). The percentage of FB2-producing A. niger strains was similar in the USA and Italian populations; however, the predominance of A. niger in the USA population suggests a higher potential for fumonisin production. Some strains with fum8 present in the genome did not produce FB2 in vitro, confirming the ineffectiveness of fum8 presence as a predictor of FB2 production.


      PubDate: 2014-08-04T16:53:40Z
       
  • Bacterial maximum non-inhibitory and minimum inhibitory concentrations of
           different water activity depressing solutes
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): G. Cebrián , C. Arroyo , P. Mañas , S. Condón
      The NaCl MNICs (maximum non-inhibitory concentrations) and MICs (minimum inhibitory concentrations) for growth of various strains of six bacterial species were determined and then compared with those obtained for seven other solutes. The influence of prior growth conditions on the MNICs and MICs was also evaluated. No significant changes on the MNICs and MICs were found among the strains studied within each species. Among all factors investigated, only growth phase –for Gram-negatives– and growth at high NaCl concentrations led to a change in the NaCl MNICs. Species could be classified depending on its NaCl MNICs and MICs (in decreasing order) as follows: Staphylococcus aureus, Listeria monocytogenes, Cronobacter sakazakii, Enterococcus faecium, Escherichia coli and Salmonella Typhimurium. Similar results were obtained for KCl, LiCl, and sodium acetate, but not for the remaining solutes investigated (sucrose, glycerol, MgCl2 and CaCl2). Results obtained indicate that, in general, Gram-negatives showed lower MNICs and MICs than Gram-positives for all the solutes, S. aureus being the most solute tolerant microorganism. When compared on a molar basis, glycerol showed the highest MNICs and MICs for all the microorganisms –except for S. aureus- and LiCl the lowest ones. NaCl MNICs and MICs were not significantly different from those of KCl when compared on a molar basis. Therefore, the inhibitory action of NaCl could not be linked to the specific action of Na+. Results also showed that the Na+ tolerance of some species was Cl− dependent whereas for others it was not, and that factors others than aw-decrease contribute to the inhibitory action of LiCl, CaCl2 and MgCl2.


      PubDate: 2014-08-04T16:53:40Z
       
  • Isolation, selection and evaluation of yeasts for use in fermentation of
           coffee beans by the wet process
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Gilberto Vinícius de Melo Pereira , Vanete Thomaz Soccol , Ashok Pandey , Adriane Bianchi Pedroni Medeiros , João Marcos Rodrigues Andrade Lara , André Luiz Gollo , Carlos Ricardo Soccol
      During wet processing of coffee, the ripe cherries are pulped, then fermented and dried. This study reports an experimental approach for target identification and selection of indigenous coffee yeasts and their potential use as starter cultures during the fermentation step of wet processing. A total of 144 yeast isolates originating from spontaneously fermenting coffee beans were identified by molecular approaches and screened for their capacity to grow under coffee-associated stress conditions. According to ITS-rRNA gene sequencing, Pichia fermentans and Pichia kluyveri were the most frequent isolates, followed by Candida Candida glabrata, quercitrusa, Saccharomyces sp., Pichia guilliermondii, Pichia caribbica and Hanseniaspora opuntiae. Nine stress-tolerant yeast strains were evaluated for their ability to produce aromatic compounds in a coffee pulp simulation medium and for their pectinolytic activity. P. fermentans YC5.2 produced the highest concentrations of flavor-active ester compounds (viz., ethyl acetate and isoamyl acetate), while Saccharomyces sp. YC9.15 was the best pectinase-producing strain. The potential impact of these selected yeast strains to promote flavor development in coffee beverages was investigated for inoculating coffee beans during wet fermentation trials at laboratory scale. Inoculation of a single culture of P. fermentans YC5.2 and co-culture of P. fermentans YC5.2 and Saccharomyces sp. YC9.15 enhanced significantly the formation of volatile aroma compounds during the fermentation process compared to un-inoculated control. The sensory analysis indicated that the flavor of coffee beverages was influenced by the starter cultures, being rated as having the higher sensory scores for fruity, buttery and fermented aroma. This demonstrates a complementary role of yeasts associated with coffee quality through the synthesis of yeast-specific volatile constituents. The yeast strains P. fermentans YC5.2 and Saccharomyces sp. YC9.15 have a great potential for use as starter cultures in wet processing of coffee and may possibly help to control and standardize the fermentation process and produce coffee beverages with novel and desirable flavor profiles.


      PubDate: 2014-08-04T16:53:40Z
       
  • Antimicrobial packaging of chicken fillets based on the release of
           carvacrol from chitosan/cyclodextrin films
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Laura Higueras , Gracia López-Carballo , Pilar Hernández-Muñoz , Ramón Catalá , Rafael Gavara
      Chitosan/cyclodextrin films (CS:CD) incorporating carvacrol were obtained by casting, and conditioned at 23°C and 75% relative humidity prior to being immersed in liquid carvacrol until they reached sorption equilibrium. In a previous work, the in vitro antimicrobial activity of these films was studied. In this work, active films were used to inhibit microbial growth in packaged chicken breast fillets. Samples of CS:CD films loaded with carvacrol, of different sizes and thus with different quantities of antimicrobial agent, were stuck to the aluminium lid used to seal PP/EVOH/PP cups containing 25g of chicken fillets. These samples were stored for 9days at 4°C. The packages were hermetically sealed and it was confirmed that they provided an infinite barrier to carvacrol. The partition of the antimicrobial agent within the food/packaging system was analysed. The antimicrobial devices rapidly released a large percentage of the agent load, amounts that were gained by the adhesive coating of the lid and especially by the chicken fillets. The latter were the main sorbent phase, with average concentrations ranging between 200 and 5000mg/Kg during the period of storage. The microbiota of the packaged fresh chicken fillets – mesophiles, psychrophiles, Pseudomonas spp., enterobacteria, lactic acid bacteria and yeasts and fungi – were analysed and monitored during storage. A general microbial inhibition was observed, increasing with the size of the active device. Inhibition with a 24cm2 device ranged from 0.3 log reductions against lactic acid bacteria to 1.8logs against yeasts and fungi. However, the large amount of antimicrobial that was sorbed or that reacted with the fillet caused an unacceptable sensory deterioration. These high sorption values are probably due to a great chemical compatibility between chicken proteins and carvacrol.


      PubDate: 2014-08-04T16:53:40Z
       
  • Biodegradation of ochratoxin A by Pediococcus parvulus isolated from Douro
           wines
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Luís Abrunhosa , António Inês , Ana I. Rodrigues , Ana Guimarães , Vânia L. Pereira , Pier Parpot , Arlete Mendes-Faia , Armando Venâncio
      Lactic acid bacteria (LAB) are a promising solution to reduce exposure to dietary mycotoxins because of the unique mycotoxin decontaminating characteristic of some LAB. Ochratoxin A (OTA) is one of the most prominent mycotoxins found in agricultural commodities. The present work reports on the ability of Pediococcus parvulus strains that were isolated from Douro wines that spontaneously underwent malolactic fermentation to detoxify OTA. These strains were identified and characterised using a polyphasic approach that employed both phenotypic and genotypic methods. When cultivated on OTA-supplemented MRS media, OTA was biodegraded into OTα by certain P. parvulus strains. The presence of OTα was confirmed using LC–MS/MS. The conversion of OTA into OTα indicates that the OTA amide bond was hydrolysed by a putative peptidase. The rate of OTA biodegradation was found to be dependent on the inoculum size and on the incubation temperature. Adsorption assays with dead P. parvulus cells showed that approximately 1.3%±1.0 of the OTA was adsorbed onto cells wall, which excludes this mechanism in the elimination of OTA by strains that degrades OTA. Under optimum conditions, 50% and 90% of OTA were degraded in 6 and 19h, respectively. Other LAB strains that belonged to different species were tested but did not degrade OTA. OTA biodegradation by P. parvulus UTAD 473 was observed in grape must. Because some P. parvulus strains have relevant probiotic properties, the strains that were identified could be particularly relevant to food and feed applications to counteract the toxic effects of OTA.


      PubDate: 2014-08-04T16:53:40Z
       
  • Influence of tea extract supplementation on bifidobacteria during soymilk
           fermentation
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Danyue Zhao , Nagendra P. Shah
      In this study, the influence of tea extract (TE) supplementation on the viability and membrane lipid compositions of Bifidobacterium was investigated. Fermented soymilk-tea (SMT) was produced by culturing selected bifidobacteria in soymilk supplemented with green or black TE. Culturability of four bacteria in the presence of various concentrations of TE was examined by plate count method. Bifidobacterium longum CSCC 5089 (BL5089) and B. longum CSCC 5022 (BL5022) were selected for further study based on their sensitivity to TE. The effect of TE supplementation on bacterial cell viability and integrity was assessed by flow cytometry in combination with fluorescence probes. Total lipids of bacterial cell were extracted using an enzyme-assistant extraction method. Fatty acids (FAs) were determined and quantified by GC–MS. Phospholipids (PLs) were separated by high performance thin-layer chromatography (HPTLC) and their relative abundances were determined by densitometry. Total tea phenolic content (TTP) in SMTs with varying concentrations of TE was quantified by HPLC. Among the four Bifidobacterium monitored, TE only significantly inhibited BL5089 (p<0.01) in a dose-dependent manner, with minimum inhibition concentrations (MICs) determined to be 15.45mg/mL TTP for green TE and 7.34mg/mL TTP for black TE. Flow cytometric analysis revealed different staining patterns of cell populations and compromise in cell integrity upon exposure to high concentrations of TE. Results from GC–MS showed that unsaturated to saturated FA ratios significantly decreased (p<0.01) in the membrane of BL5089 cells upon TE exposure. Separation of PLs by HPTLC showed dramatic alterations in phosphatidylcholine and phosphatidylglycerol contents due to TE treatment.


      PubDate: 2014-08-04T16:53:40Z
       
  • Editorial Board
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187




      PubDate: 2014-08-04T16:53:40Z
       
  • Corrigendum to “Isolation of methyl syringate as a specific
           aflatoxin production inhibitor from the essential oil of Betula alba and
           aflatoxin production inhibitory activities of its related
           compounds.”[Int. J. Food Microbiol. 153 (2012) 339–344]
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Usuma Jermnak , Tomoya Yoshinari , Yasumasa Sugiyama , Rie Tsuyuki , Hiromichi Nagasawa , Shohei Sakuda



      PubDate: 2014-08-04T16:53:40Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187




      PubDate: 2014-08-04T16:53:40Z
       
  • Isolation and characterization of bifidobacteria from ovine cheese
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Vera Bunesova , Jiri Killer , Eva Vlkova , Sarka Musilova , Martin Tomaska , Vojtech Rada , Vladimir Kmet
      Animal products are one of the niches of bifidobacteria, a fact probably attributable to secondary contamination. In this study, 2 species of the genus Bifidobacterium were isolated by culture-dependent methods from ovine cheeses that were made from unpasteurized milk without addition of starter cultures. The isolates were identified as Bifidobacterium crudilactis and Bifidobacterium animalis subsp. lactis using matrix-assisted laser desorption/ionization time-of-flight analysis and sequencing of phylogenetic markers (16S rRNA, hsp60, and fusA).


      PubDate: 2014-08-04T16:53:40Z
       
  • Eating oysters without risk of vibriosis: Application of a bacteriophage
           against Vibrio parahaemolyticus in oysters
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Jin Woo Jun , Hyoun Joong Kim , Sae Kil Yun , Ji Young Chai , Se Chang Park
      Vibrio parahaemolyticus is a major cause of foodborne illness and related with the consumption of raw contaminated seafood, especially oysters. To evaluate the effectiveness of various applications of a bacteriophage (phage), pVp-1, against a multiple-antibiotic-resistant V. parahaemolyticus pandemic strain (CRS 09-17), we designed artificial contamination models that are most likely to be encountered during oyster processing. When live oysters were treated with bath immersion with pVp-1 after CRS 09-17 challenge, the growth of bacterial strain was significantly reduced. After 72h of phage application with bath immersion, bacterial growth reduction was observed to be 8.9×106 CFU/ml (control group) to 1.4×10CFU/ml (treatment group). When pVp-1 was surface-applied on the flesh of oysters after CRS 09-17 inoculation, bacterial growth was properly inhibited. After 12h of phage application on the surface of oysters, bacterial growth inhibition was revealed to be 1.44×106 CFU/ml (control group) to 1.94CFU/ml (treatment group). This is the first report, to the best of our knowledge, of oyster surface-application of a phage against a multiple-antibiotic-resistant V. parahaemolyticus pandemic strain, and our successful phage application to various situations emphasizes the potential use of the phage to avoid V. parahaemolyticus infection from aquaculture to consumption.


      PubDate: 2014-08-04T16:53:40Z
       
  • α-Acetolactate synthase of Lactococcus lactis contributes to pH
           homeostasis in acid stress conditions
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Federico A. Zuljan , Guillermo D. Repizo , Sergio H. Alarcon , Christian Magni
      Lactic Acid Bacteria (LAB) are recognized as safe microorganisms with the capacity to improve the quality of dairy products. When the LAB Lactococcus lactis is employed as starter for the production of fermented foods, high quantities of important aroma compounds such as diacetyl are generated by means of the diacetyl/acetoin pathway. Our previous results obtained with L. lactis strains report that this pathway is activated under acidic conditions. In this study, we describe the metabolism of pyruvate, a diacetyl/acetoin precursor, and its contribution to pH homeostasis in this microorganism. L lactis strain IL1403 is able to cometabolize pyruvate and glucose at low pH, producing lactate, acetate as well as diacetyl/acetoin compounds. In contrast, the als defective strain, which is incapable of producing C4 compounds, appeared sensitive to pyruvate under acidic conditions rendering it unable to grow. Accordingly, the als-mutant strain showed a simultaneous inability to alkalinize internal and external media. These results demonstrate that the decarboxylation reactions associated to the diacetyl/acetoin pathway represent a competitive advantage in a condition of intracellular pyruvate accumulation during growth at low pH. Interestingly, a genomic comparative analysis shows that this pathway has been conserved in L. lactis during the domestication of different strains. Also, our analysis shows that the recent acquisition of the cit cluster required for citrate metabolism, which contributes to diacetyl/acetoin production as well, is the specific feature of the biovar. diacetylactis. In this regard, we present for first time genetic evidence supporting the proposal made by Passerini et al. (2013) who postulated that the expression “biovar. citrate” should be more appropriate to define this specific industrial strain.


      PubDate: 2014-08-04T16:53:40Z
       
  • Efficacy of gaseous chlorine dioxide in inactivating Bacillus cereus
           spores attached to and in a biofilm on stainless steel
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Hyegyeong Nam , Hyun-Sun Seo , Jihyun Bang , Hoikyung Kim , Larry R. Beuchat , Jee-Hoon Ryu
      We evaluated the lethal activity of gaseous chlorine dioxide (ClO2) against Bacillus cereus spores attached to and in biofilm formed on a stainless steel surface. Aqueous ClO2 was prepared by mixing sulfuric acid (5% w/v) with sodium chlorite (10mg/mL), and gaseous ClO2 was produced by vaporization of aqueous ClO2 in an air-tight container. The concentration of gaseous ClO2 in the air within the container increased rapidly at first but gradually decreased over time. The lethality of gaseous ClO2 against B. cereus spores attached to stainless steel coupons (SSCs) and in biofilm formed by the pathogen on SSCs was determined. The B. cereus spores attached to SSCs (5.3±0.1logCFU/coupon) were completely inactivated within 1h at 25°C when treated with gaseous ClO2 (peak concentration: 115.3±5.0 parts per million [ppm]). The total number of vegetative cells and spores in biofilm formed by B. cereus on SSCs was 5.9±0.3logCFU/coupon; the spore count was 5.3±0.1logCFU/coupon. The vegetative cells and spores in biofilm were completely inactivated within 6h (peak concentration: 115.3±5.0ppm). Results show that B. cereus spores in biofilms are more resistant to gaseous ClO2 than are attached spores not in biofilms. Gaseous ClO2 was, nevertheless, very effective in killing B. cereus spores in biofilm on the surface of stainless steel. Results show promise for application of gaseous ClO2 to enhance the microbiological safety of foods that may come in contact with stainless steel and possibly other hard surfaces on which B. cereus biofilms have formed.


      PubDate: 2014-08-04T16:53:40Z
       
  • Modelling the effect of lactic acid bacteria from starter- and aroma
           culture on growth of Listeria monocytogenes in cottage cheese
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Nina Bjerre Østergaard , Annelie Eklöw , Paw Dalgaard
      Four mathematical models were developed and validated for simultaneous growth of mesophilic lactic acid bacteria from added cultures and Listeria monocytogenes, during chilled storage of cottage cheese with fresh- or cultured cream dressing. The mathematical models include the effect of temperature, pH, NaCl, lactic- and sorbic acid and the interaction between these environmental factors. Growth models were developed by combining new and existing cardinal parameter values. Subsequently, the reference growth rate parameters (μref at 25°C) were fitted to a total of 52 growth rates from cottage cheese to improve model performance. The inhibiting effect of mesophilic lactic acid bacteria from added cultures on growth of L. monocytogenes was efficiently modelled using the Jameson approach. The new models appropriately predicted the maximum population density of L. monocytogenes in cottage cheese. The developed models were successfully validated by using 25 growth rates for L. monocytogenes, 17 growth rates for lactic acid bacteria and a total of 26 growth curves for simultaneous growth of L. monocytogenes and lactic acid bacteria in cottage cheese. These data were used in combination with bias- and accuracy factors and with the concept of acceptable simulation zone. Evaluation of predicted growth rates of L. monocytogenes in cottage cheese with fresh- or cultured cream dressing resulted in bias-factors (Bf) of 1.07–1.10 with corresponding accuracy factor (Af) values of 1.11 to 1.22. Lactic acid bacteria from added starter culture were on average predicted to grow 16% faster than observed (Bf of 1.16 and Af of 1.32) and growth of the diacetyl producing aroma culture was on average predicted 9% slower than observed (Bf of 0.91 and Af of 1.17). The acceptable simulation zone method showed the new models to successfully predict maximum population density of L. monocytogenes when growing together with lactic acid bacteria in cottage cheese. 11 of 13 simulations of L. monocytogenes growth were within the acceptable simulation zone, which demonstrated good performance of the empirical inter-bacterial interaction model. The new set of models can be used to predict simultaneous growth of mesophilic lactic acid bacteria and L. monocytogenes in cottage cheese during chilled storage at constant and dynamic temperatures. The applied methodology is likely to be applicable for safety prediction of other types of fermented and unripened dairy products where inhibition by lactic acid bacteria is important for growth of pathogenic microorganisms.


      PubDate: 2014-08-04T16:53:40Z
       
  • Development of a colony hybridization method for the enumeration of total
           and potentially enteropathogenic Vibrio parahaemolyticus in shellfish
    • Abstract: Publication date: 1 September 2014
      Source:International Journal of Food Microbiology, Volume 186
      Author(s): Elisabetta Suffredini , Loredana Cozzi , Gianni Ciccaglioni , Luciana Croci
      Vibrio parahaemolyticus is a marine microorganism, recognized as cause of gastroenteritis outbreaks associated with seafood consumption. In this study the development and the in-house validation of a colony hybridization method for the enumeration of total and potentially pathogenic V. parahaemolyticus is reported. The method included a set of three controls (process, hybridization and detection control) for the full monitoring of the analytical procedure. Four digoxigenin-labeled probes were designed for pathogenic strains enumeration (tdh1, tdh2, trh1 and trh2 probes) and one for total V. parahaemolyticus count (toxR probe). Probes were tested on a panel of 70 reference strains and 356 environmental, food and clinical isolates, determining the inclusivity (tdh: 96.7%, trh: 97.8%, toxR: 99.4%) and the exclusivity (100% for all probes). Accuracy and linearity of the enumeration were evaluated on pure and mixed cultures: slopes of the regression lines ranged from 0.957 to 1.058 depending on the target gene and R2 was greater than or equal to 0.989 for all reactions. Evaluation was also carried on using four experimentally contaminated seafood matrices (shellfish, finfish, crustaceans and cephalopods) and the slopes of the curves varied from 0.895 (finfish) to 0.987 (cephalopods) for the counts of potentially pathogenic V. parahaemolyticus (R2 ≥0.965) and from 0.965 to 1.073 for total V. parahaemolyticus enumeration (R2 ≥0.981). Validation was performed on 104 naturally contaminated shellfish samples, analyzed in parallel by colony hybridization, ISO/TS 21872-1 and MPN enumeration. Colony hybridization and ISO method showed a relative accuracy of 86.7%, and a statistically significant correlation was present between colony hybridization enumeration and MPN results (r =0.744, p<0.001). The proposed colony hybridization can be a suitable alternative method for the enumeration of total and potentially pathogenic V. parahaemolyticus in seafood.


      PubDate: 2014-07-27T16:18:03Z
       
  • Brazil nuts are subject to infection with B and G aflatoxin-producing
           fungus, Aspergillus pseudonomius
    • Abstract: Publication date: 1 September 2014
      Source:International Journal of Food Microbiology, Volume 186
      Author(s): Fernanda Pelisson Massi , Maria Lúcia Carneiro Vieira , Daniele Sartori , Rafael Elias Silva Penha , Carla de Freitas Munhoz , Josué Maldonado Ferreira , Beatriz Thie Iamanaka , Marta Hiromi Taniwaki , Jens C. Frisvad , Maria Helena Pelegrinelli Fungaro
      The exploitation of the Brazil nut is one of the most important activities of the extractive communities of the Amazon rainforest. However, its commercialization can be affected by the presence of aflatoxins produced by fungi, namely Aspergillus section Flavi. In the present study, we investigated a collection of Aspergillus nomius strains isolated from Brazil nuts using different approaches, including morphological characters, RAPD and AFLP profiles, partial β-tubulin and calmodulin nucleotide sequences, aflatoxin patterns, as well as tolerance to low water activity in cultured media. Results showed that most of the isolates do belong to A. nomius species, but a few were re-identified as Aspergillus pseudonomius, a very recently described species. The results of the analyses of molecular variance, as well as the high pairwise FST values between A. nomius and A. pseudonomius suggested the isolation between these two species and the inexistence of gene flow. Fixed interspecific nucleotide polymorphisms at β-tubulin and calmodulin loci are presented. All A. pseudonomius strains analyzed produced aflatoxins AFB1, AFB2, AFG1 and AFG2. This study contains the first-ever report on the occurrence in Brazil nuts of A. pseudonomius. The G-type aflatoxins and the mycotoxin tenuazonic acid are reported here for the first time in A. pseudonomius.


      PubDate: 2014-07-27T16:18:03Z
       
  • Editorial Board
    • Abstract: Publication date: 1 September 2014
      Source:International Journal of Food Microbiology, Volume 186




      PubDate: 2014-07-27T16:18:03Z
       
  • Real-time PCR method combined with immunomagnetic separation for detecting
           healthy and heat-injured Salmonella Typhimurium on raw duck wings
    • Abstract: Publication date: 1 September 2014
      Source:International Journal of Food Microbiology, Volume 186
      Author(s): Qianwang Zheng , Marta Mikš-Krajnik , Yishan Yang , Wang Xu , Hyun-Gyun Yuk
      Conventional culture detection methods are time consuming and labor-intensive. For this reason, an alternative rapid method combining real-time PCR and immunomagnetic separation (IMS) was investigated in this study to detect both healthy and heat-injured Salmonella Typhimurium on raw duck wings. Firstly, the IMS method was optimized by determining the capture efficiency of Dynabeads® on Salmonella cells on raw duck wings with different bead incubation (10, 30 and 60min) and magnetic separation (3, 10 and 30min) times. Secondly, three Taqman primer sets, Sal, invA and ttr, were evaluated to optimize the real-time PCR protocol by comparing five parameters: inclusivity, exclusivity, PCR efficiency, detection probability and limit of detection (LOD). Thirdly, the optimized real-time PCR, in combination with IMS (PCR–IMS) assay, was compared with a standard ISO and a real-time PCR (PCR) method by analyzing artificially inoculated raw duck wings with healthy and heat-injured Salmonella cells at 101 and 100 CFU/25g. Finally, the optimized PCR–IMS assay was validated for Salmonella detection in naturally contaminated raw duck wing samples. Under optimal IMS conditions (30min bead incubation and 3min magnetic separation times), approximately 85 and 64% of S. Typhimurium cells were captured by Dynabeads® from pure culture and inoculated raw duck wings, respectively. Although Sal and ttr primers exhibited 100% inclusivity and exclusivity for 16 Salmonella spp. and 36 non-Salmonella strains, the Sal primer showed lower LOD (103 CFU/ml) and higher PCR efficiency (94.1%) than the invA and ttr primers. Moreover, for Sal and invA primers, 100% detection probability on raw duck wings suspension was observed at 103 and 104 CFU/ml with and without IMS, respectively. Thus, the Sal primer was chosen for further experiments. The optimized PCR–IMS method was significantly (P =0.0011) better at detecting healthy Salmonella cells after 7-h enrichment than traditional PCR method. However there was no significant difference between the two methods with longer enrichment time (14h). The diagnostic accuracy of PCR–IMS was shown to be 98.3% through the validation study. These results indicate that the optimized PCR–IMS method in this study could provide a sensitive, specific and rapid detection method for Salmonella on raw duck wings, enabling 10-h detection. However, a longer enrichment time could be needed for resuscitation and reliable detection of heat-injured cells.


      PubDate: 2014-07-27T16:18:03Z
       
  • Detection of qnr, aac(6′)-Ib-cr and qepA genes in Escherichia coli
           isolated from cooked meat products in Henan, China
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Xiaobing Jiang , Tao Yu , Nan Wu , Hecheng Meng , Lei Shi
      Antimicrobial resistance in Escherichia coli has increased in recent years in China. Antimicrobial resistant isolates and resistance genes of E. coli can be transferred to humans through the food chain and this presents a public health risk. However, few studies have investigated the prevalence of antimicrobial resistance-encoding genes in E. coli isolated from food samples in China. The aim of this study was to investigate the presence of quinolone resistance genes (QRGs) and extended-spectrum β-lactamases (ESBLs) in E. coli isolated from cooked meat products in Henan, China. A total of 75 E. coli isolates (12.1%) were detected from 620 samples. High rates of resistance to the following drugs were observed: tetracycline (56.0%), trimethoprim/sulfamethoxazole (41.3%), streptomycin (29.3%), ampicillin (26.7%) and nalidixic acid (14.7%). Of the 75 isolates, QRGs were present in 10 isolates (13.3%), with qnr and aac(6′)-Ib-cr detected alone or in combination in five (6.7%) and eight isolates (10.7%). The qnr genes detected in this study included qnrS (n=3) and qnrA (n=2). The qepA gene was absent among these isolates. Three types of β-lactamase genes were identified in the five ESBL-producing E. coli isolates: bla CTX-M-1, bla CTX-M-9, and bla TEM-1. The qnrS gene was found to be co-transferred with bla CTX-M-1 and bla TEM-1 in one isolate. Our data suggest that cooked meat products may act as reservoirs for multi-resistant bacteria and facilitate the dissemination of antimicrobial resistance genes.


      PubDate: 2014-07-27T16:18:03Z
       
  • Inhibition of Campylobacter jejuni on fresh chicken breasts by
           κ-carrageenan/chitosan-based coatings containing allyl isothiocyanate
           or deodorized oriental mustard extract
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Amin N. Olaimat , Yuan Fang , Richard A. Holley
      Campylobacter species are common bacterial pathogens associated with human gastroenteritis worldwide. The objectives of this study were to determine the minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations of allyl isothiocyanate (AITC) against 4 Campylobacter jejuni strains in Mueller–Hinton (MH) broth at 4, 21, 37 and 42°C and to screen the C. jejuni strains for their ability to degrade sinigrin (which forms AITC) in pH7.0 MH broth at 35°C for 21d. Also evaluated was the antimicrobial activity of an edible 0.2% κ-carrageenan/2% chitosan-based coating containing AITC or deodorized oriental mustard extract against a 4 strain C. jejuni cocktail (6.2log10 CFU/g) on vacuum-packaged fresh chicken breasts during 4°C storage. MIC values of AITC were 0.63 to 1.25ppm and 2.5 to 5ppm against tested strains at 37 and 42°C, respectively. However, the MBC was 2.5 and 5ppm at 37 and 42°C, respectively, and increased to a range of 40 to 160ppm at 4°C. κ-Carrageenan/chitosan-based coatings containing 50 or 100μl/g AITC reduced viable C. jejuni to undetectable levels on chicken breast after 5d at 4°C, while 25μl/g AITC or 200 to 300mg/g mustard extract in coatings reduced C. jejuni numbers by 1.75 to 2.78log10 CFU/g more than control coatings without antimicrobial. Both oriental mustard extract (50 to 300mg/g) and AITC (≥25μl/g) reduced aerobic bacteria by 1.72 to 2.75log10 CFU/g and lactic acid bacteria (LAB) by 0.94 to 3.36log10 CFU/g by 21d compared to the control coating. κ-Carrageenan/chitosan coatings containing ≥50μl/g AITC or ≥300mg/g oriental mustard showed excellent potential to control C. jejuni viability on raw chicken.


      PubDate: 2014-07-27T16:18:03Z
       
  • The use of real-time PCR to study Penicillium chrysogenum growth kinetics
           on solid food at different water activities
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): J.M.R. Apollo Arquiza , Jean Hunter
      Fungal growth on solid foods can make them unfit for human consumption, but certain specialty foods require fungi to produce their characteristic properties. In either case, a reliable way of measuring biomass is needed to study how various factors (e.g. water activity) affect fungal growth rates on these substrates. Biochemical markers such as chitin, glucosamine or ergosterol have been used to estimate fungal growth, but they cannot distinguish between individual species in mixed culture. In this study, a real-time polymerase chain reaction (rt-PCR) protocol specific for a target fungal species was used to quantify its DNA while growing on solid food. The measured amount of DNA was then related to the biomass present using an experimentally determined DNA-to-biomass ratio. The highly sensitive rt-PCR biomass assay was found to have a wide range, able to quantify the target DNA within a six orders-of-magnitude difference. The method was used to monitor germination and growth of Penicillium chrysogenum spores on a model porous food (cooked wheat flour) at 25°C and different water activities of 0.973, 0.936, and 0.843. No growth was observed at 0.843, but lag, exponential and stationary phases were identified in the growth curves for the higher water activities. The calculated specific growth rates (μ) during the exponential phase were almost identical, at 0.075/h and 0.076/h for aw=0.973 and 0.936, respectively. The specificity of the method was demonstrated by measuring the biomass of P. chrysogenum while growing together with Aspergillus niger on solid media at aw=0.973.


      PubDate: 2014-07-27T16:18:03Z
       
  • Presence of Helicobacter suis on pork carcasses
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): L. De Cooman , K. Houf , A. Smet , B. Flahou , R. Ducatelle , E. De Bruyne , F. Pasmans , F. Haesebrouck
      Helicobacter (H.) suis is a world-wide spread pathogen which not only colonizes the stomach of pigs, but is also the most prevalent gastric non-H. pylori Helicobacter (NHPH) species in humans. H. suis infections are associated with gastric lesions both in pigs and in humans. Recently, the presence of viable H. suis bacteria has been demonstrated in minced pork, suggesting that manipulation or consumption of contaminated pig meat is a possible route of transmission of this zoonotic agent. The main goal of this study was to determine the extent of pork carcass contamination with H. suis at slaughter. In two consecutive studies, the occurrence of H. suis DNA was assessed in scalding water, head and mouth swabs, mesenteric lymph nodes, palatine tonsils and on the chest, shoulder and ham region of pork carcasses from three slaughterhouses using qPCR with ureA gene based H. suis-specific primers. H. suis DNA was detected on carcasses in all slaughterhouses, in 8.3% of all 1083 samples. It was found in all sampled matrices, except for the palatine tonsils and scalding water samples. Contamination levels of dressed pork samples did not exceed 184 genomic equivalents per 100cm2 (shoulder, ham) or 300cm2 (chest). All positive PCR products were subjected to sequence analysis of the ureA gene to confirm the identification of H. suis bacteria. Using multilocus sequence typing (MLST) on a selection of the positive samples, 5 unique sequence types (STs) could be assigned. Multiple H. suis strains were present on samples derived from one specific pig herd. Since H. suis DNA was detected in 11% (n: 90) of the mesenteric lymph nodes derived at the slaughterhouse, it was determined whether these organisms can colonize the mesenteric lymph nodes after experimental infection. Despite high-level colonization of the porcine stomachs with the H. suis strain, no H. suis DNA was detected in the mesenteric lymph nodes at four weeks after experimental infection. This might indicate that its presence in these tissues of slaughtered pigs is due to contamination during the slaughter process, but further studies are necessary to confirm this. In conclusion, we demonstrate a relatively high prevalence of H. suis on pork carcasses.


      PubDate: 2014-07-27T16:18:03Z
       
  • The predominance, biodiversity and biotechnological properties of
           
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Rosanna Tofalo , Giuseppe Fasoli , Maria Schirone , Giorgia Perpetuini , Alessia Pepe , Aldo Corsetti , Giovanna Suzzi
      Pecorino di Farindola is a handicraft cheese made by farmers on small scale using raw ewes' milk and pig rennet. In this study, yeast consortia were evaluated during Pecorino di Farindola making and ripening. Molecular identification of 156 isolates was achieved by a combination of PCR-RFLP of the 5.8S ITS rRNA region and sequencing of the D1/D2 domain of the 26S rRNA gene. Kluyveromyces marxianus was the predominant species, while other species (Pichia kudriavzevii, Candida parapsilosis, Candida glaebosa and Candida zeylanoides) were present only during the early weeks of ripening. Moreover, the isolates were differentiated both by RAPD-PCR and a sequence alignment of D1/D2 26S rRNA gene, revealing different K. marxianus profiles and variants, and suggesting the role of local selective pressure as the origin of distinctive K. marxianus populations. The strains were characterized also on the basis of different dairy properties such as growth temperature, lactose, galactose, lactate and citrate assimilation at different NaCl concentrations, as well as lipolytic and caseinolytic activities. Moreover, 39 selected K. marxianus strains were inoculated in pasteurized whey to evaluate their growth kinetics, besides lactose, lactate and free amino acids metabolism. The growth kinetics distinguished different biotypes and different metabolic behavior were determined. The general picture of K. marxianus population from Pecorino di Farindola shows a high biodiversity at genetic and phenotypic levels that potentially offers many opportunities for new and advanced knowledge at species level, providing in the meantime a good basis to study the relationship between genetic variability and functional diversities.


      PubDate: 2014-07-27T16:18:03Z
       
  • A multi-approach study of influence of growth temperature and nutrient
           deprivation in a strain of Aeromonas hydrophila
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Francesca Bruscolini , Federica Barbieri , Michela Battistelli , Michele Betti , Sabrina Dominici , Anita Manti , Paola Boi , Francesco Marinelli , Stefano Papa , Anna Pianetti
      In the present study we investigated the behavior of an Aeromonas hydrophila strain in prolonged nutrient deprivation condition analyzing the possible link among survival, cell morphology and adhesive characteristics and correlating them with the expression of the 43kDa outer membrane protein (OMP). The strain was inoculated in mineral and drinking chlorinated water, and in Nutrient Broth as a control with incubation at 4 and 24°C for 176days. Specimens were analyzed at different times during starvation stress. Viability was assessed by flow cytometry and growth by plate count technique; morphology and adhesivity were detected by optical and electron microscopy. The 43kDa OMP expression at different times was determined after immunoblotting assay using a polyclonal antibody produced in rabbit. The results showed a long-term viability as evidenced by cytofluorimetric analysis; however, the prolonged starvation led to the shift from the normal rod shaped cells to spherical forms in the last phases of incubation especially at 24°C. Concomitantly with the appearance of spherical cells we noted a reduction of the 43kDa OMP content and adhesive ability. Therefore, our results suggest a role of the 43kDa OMP as adhesin in A. hydrophila. In conclusion, we demonstrated that the bacterium can long survive under stress conditions, however adopting strategies which can lead to a loss of some cell surface components involved in the interactions with eukaryotic cells, therefore modifying its virulence properties.


      PubDate: 2014-07-27T16:18:03Z
       
  • Survival and death kinetics of Salmonella strains at low relative
           humidity, attached to stainless steel surfaces
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Edyta Margas , Nicolas Meneses , Beatrice Conde-Petit , Christine E.R. Dodd , John Holah
      Salmonella is a major pathogen of concern for low water activity foods and understanding its persistence in dry food processing environments is important for producing safe food. The studies sought to assess the survival of 15 isolates of Salmonella on stainless steel surfaces. Additionally, the aim was to select a suitable model to describe and understand the strains' survival kinetics. Salmonella isolates were dried onto stainless steel surfaces, placed in controlled temperature (25°C) and humidity (33%) conditions and their viability assessed at times from 1h to 30days. The highest survival rate was associated with S. Typhimurium DT104, S. Muenchen, and S. Typhimurium (NCTC 12023), where, after 30days, the reduction ranged from 1.3log10 cfu/surface to 1.6log10 cfu/surface. The lowest survival was linked to a S. Typhimurium strain used in European Standard disinfectant approval tests and S. Typhimurium isolated from whey powder. For most of the strains, following an initial reduction in viability in the first hours (<72h), no further reduction was seen over the 30day period; therefore a 2-population Weibull model was fitted to model the survival kinetics. The overall survival was neither serotype nor time related. All strains had two different subpopulations, one more resistant to desiccation than the other. The results indicate the possibility of the long term survival of Salmonella on environmental surfaces (at least 30days) and suggest the most suitable model to describe and predict survival kinetics. The results also identify strains that may be used to study stress response mechanisms and potential factory control measures in future studies.


      PubDate: 2014-07-27T16:18:03Z
       
  • Effectiveness of a novel spontaneous carvacrol nanoemulsion against
           Salmonella enterica Enteritidis and Escherichia coli O157:H7 on
           contaminated mung bean and alfalfa seeds
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Kyle S. Landry , Yuhua Chang , David Julian McClements , Lynne McLandsborough
      Outbreaks of foodborne illness from consumption of sprouts have been linked to contaminated seeds prior to germination. Due to the long sprouting period at ambient temperatures and high humidity, germinating seeds contaminated with low pathogen levels (0.1logCFU/g) can result in sprouts with high numbers (≥108 CFU/g) of pathogens. Currently, the recommended treatment method involves soaking seeds in 20,000ppm (2%) calcium hypochlorite prior to germination. In this study, an alternative treatment involving soaking seeds in a carvacrol nanoemulsion was tested for its efficacy against Salmonella enterica subspecies enterica serovar Enteritidis (ATCC BAA-1045) or EGFP expressing E. coli O157:H7 (ATCC 42895) contaminated mung bean and alfalfa seeds. The antimicrobial treatment was performed by soaking inoculated seed batches in the spontaneous nanoemulsion (4000 or 8000ppm) for 30 or 60min. The spontaneous nanoemulsion was formed by titrating the oil phase (carvacrol and medium chain triglycerides) and water-soluble surfactant (Tween 80®) into sodium citrate buffer. Following treatment, the numbers of surviving cells were determined by suspending the seeds in TSB and performing plate counts and/or Most Probable Number (MPN) enumeration. Treated seeds were sprouted and tested for the presence of the appropriate pathogen. This treatment successfully inactivated low levels (2 and 3logCFU/g) of S. Enteritidis and E. coli on either seed types when soaked for either 30 or 60min at nanoemulsion concentrations corresponding to 4000 (0.4%) or 8000 (0.8%) ppm carvacrol. Inoculated alfalfa seeds treated with 4000ppm nanoemulsion, required a 60min treatment time to show a similar 2–3 log reduction. Complete inactivation was confirmed by germinating treated seeds and performing microbiological testing. Total sprout yield was not compromised by any of the tested treatments. These results show that carvacrol nanoemulsions may be an alternative antimicrobial treatment method for mung bean and alfalfa seeds.


      PubDate: 2014-07-27T16:18:03Z
       
  • DNase I and proteinase K impair Listeria monocytogenes biofilm formation
           and induce dispersal of pre-existing biofilms
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Uyen T. Nguyen , Lori L. Burrows
      Current sanitation methods in the food industry are not always sufficient for prevention or dispersal of Listeria monocytogenes biofilms. Here, we determined if prevention of adherence or dispersal of existing biofilms could occur if biofilm matrix components were disrupted enzymatically. Addition of DNase during biofilm formation reduced attachment (<50% of control) to polystyrene. Treatment of established 72h biofilms with 100μg/ml of DNase for 24h induced incomplete biofilm dispersal, with <25% biofilm remaining compared to control. In contrast, addition of proteinase K completely inhibited biofilm formation, and 72h biofilms—including those grown under stimulatory conditions—were completely dispersed with 100μg/ml proteinase K. Generally-regarded-as-safe proteases bromelain and papain were less effective dispersants than proteinase K. In a time course assay, complete dispersal of L. monocytogenes biofilms from both polystyrene and type 304H food-grade stainless steel occurred within 5min at proteinase K concentrations above 25μg/ml. These data confirm that both DNA and proteins are required for L. monocytogenes biofilm development and maintenance, and that these components of the biofilm matrix can be targeted for effective prevention and removal of biofilms.


      PubDate: 2014-07-27T16:18:03Z
       
  • Rapid identification of the genus Dekkera/Brettanomyces, the Dekkera
           subgroup and all individual species
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): M. Hulin , E. Harrison , M. Stratford , A.E. Wheals
      The genus Dekkera/Brettanomyces comprises five described species: Dekkera bruxellensis, D. anomala, Brettanomyces custersianus, B. naardenensis and B. nanus. Some of them, especially D. bruxellensis, are important spoilage organisms, particularly in the wine and beverage industries. Because of their economic importance many different methods have been developed to identify members of the genus in general and D. bruxellensis in particular. These methods vary in their rapidity, complexity and cost but, partly because of confidentiality issues, it is unclear which methods are used, or how widely, in the relevant industries. Building on previous work with the genera Saccharomyces and Zygosaccharomyces, a suite of eight PCR primer pairs has been designed either on the D1–D2 region of the 26S rRNA gene or translation elongation factor TEF1-α. These primers can specifically identify the genus as a whole, only Dekkera species, each one of the five recognised species as well as a significant subgroup of D. bruxellensis represented by NCYC 3426. Multiplexing has also been tried and it has been shown to be possible with some combinations of genus or Dekkera-level and species-specific primers. Using direct colony PCR amplification followed by gel electrophoresis, a clear positive result can be obtained in less than 3h, thus providing a quick, reliable and inexpensive way to identify target species.


      PubDate: 2014-07-27T16:18:03Z
       
  • Staphylococcus aureus food-poisoning outbreak associated with the
           consumption of ice-cream
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): A. Fetsch , M. Contzen , K. Hartelt , A. Kleiser , S. Maassen , J. Rau , B. Kraushaar , F. Layer , B. Strommenger
      In April 2013, a food poisoning outbreak caused by staphylococcal enterotoxins (SEs) in ice-cream occurred in Freiburg, Germany, among the 31 participants of a christening party. Of the 13 cases, seven were hospitalized or obtained ambulatory treatment. Different types of ice-cream, which was freshly produced at the hotel where the party took place, were found to contain SE and high amounts of coagulase positive staphylococci. Enterotoxigenic Staphylococcus aureus strains isolated from ice-cream and human cases were of the same spa-type (t127), harboured the sea gene and displayed identical phenotypic resistance-, Fourier transform infrared spectroscopy- (FT-IR) and microarray-profiles. Despite the strong microbiological and epidemiological evidence of ice-cream being the incriminated food vehicle of the outbreak, a common source of S. aureus from the ice-cream could not be deduced. As none of the employees carried the outbreak strain, either the equipment used for the production of the ice-cream or a contaminated ingredient is the most likely introduction source.


      PubDate: 2014-07-27T16:18:03Z
       
  • Exploiting the explosion of information associated with whole genome
           sequencing to tackle Shiga toxin-producing Escherichia coli (STEC) in
           global food production systems
    • Abstract: Publication date: 18 September 2014
      Source:International Journal of Food Microbiology, Volume 187
      Author(s): Eelco Franz , Pascal Delaquis , Stefano Morabito , Lothar Beutin , Kari Gobius , David A. Rasko , Jim Bono , Nigel French , Jacek Osek , Bjørn-Arne Lindstedt , Maite Muniesa , Shannon Manning , Jeff LeJeune , Todd Callaway , Scott Beatson , Mark Eppinger , Tim Dallman , Ken J. Forbes , Henk Aarts , David L. Pearl , Victor P.J. Gannon , Chad R. Laing , Norval J.C. Strachan
      The rates of foodborne disease caused by gastrointestinal pathogens continue to be a concern in both the developed and developing worlds. The growing world population, the increasing complexity of agri-food networks and the wide range of foods now associated with STEC are potential drivers for increased risk of human disease. It is vital that new developments in technology, such as whole genome sequencing (WGS), are effectively utilized to help address the issues associated with these pathogenic microorganisms. This position paper, arising from an OECD funded workshop, provides a brief overview of next generation sequencing technologies and software. It then uses the agent–host–environment paradigm as a basis to investigate the potential benefits and pitfalls of WGS in the examination of (1) the evolution and virulence of STEC, (2) epidemiology from bedside diagnostics to investigations of outbreaks and sporadic cases and (3) food protection from routine analysis of foodstuffs to global food networks. A number of key recommendations are made that include: validation and standardization of acquisition, processing and storage of sequence data including the development of an open access “WGSNET”; building up of sequence databases from both prospective and retrospective isolates; development of a suite of open-access software specific for STEC accessible to non-bioinformaticians that promotes understanding of both the computational and biological aspects of the problems at hand; prioritization of research funding to both produce and integrate genotypic and phenotypic information suitable for risk assessment; training to develop a supply of individuals working in bioinformatics/software development; training for clinicians, epidemiologists, the food industry and other stakeholders to ensure uptake of the technology and finally review of progress of implementation of WGS. Currently the benefits of WGS are being slowly teased out by academic, government, and industry or private sector researchers around the world. The next phase will require a coordinated international approach to ensure that it's potential to contribute to the challenge of STEC disease can be realized in a cost effective and timely manner.


      PubDate: 2014-07-27T16:18:03Z
       
  • Prevalence and antimicrobial susceptibility of Arcobacter species in cow
           milk, water buffalo milk and fresh village cheese
    • Abstract: Publication date: 1 October 2014
      Source:International Journal of Food Microbiology, Volume 188
      Author(s): Simten Yesilmen , Aydin Vural , Mehmet Emin Erkan , Ibrahim Halil Yildirim
      In this study, the presence of Arcobacter spp. was examined in cow milk (n =50), water buffalo (WB) milk (n =50) and fresh village cheese (n =50) samples. The 16S rDNA-RFLP method was used for the identification of Arcobacter spp. The disc diffusion method was used to investigate the susceptibility of all strains identified to 18 different antimicrobial substances. The most commonly isolated Arcobacter species were found to be Arcobacter butzleri (38.89%), Arcobacter cryaerophilus (22.23%) and Arcobacter skirrowii (11.12%) in cow milk; A. cryaerophilus (33.33%), Arcobacter cibarius (20.83%) and A. butzleri (12.50%) in WB milk; and A. skirrowii (28.57%), A. butzleri (21.43%) and A. cryaerophilus (14.29%) in fresh village cheese. This is the first study to identify the presence of Arcobacter nitrofigilis, Arcobacter cloacae, Arcobacter halophilus, Arcobacter bivalviorum and A. cibarius species in analyzed samples. It was found that all of the A. cryaerophilus (n:16) isolates were resistant to cefoperazone, cloxacillin and penicillin G; all of the A. skirrowii (n:12) and A. butzleri (n:10) isolates were resistant to cefoperazone, tetracycline, ampicillin, erythromycin, cloxacillin and penicillin G. It was concluded that cow milk, WB milk and fresh village cheese samples are an important source of Arcobacter species and pose a risk to public health.


      PubDate: 2014-07-27T16:18:03Z
       
 
 
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