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  Subjects -> BIOLOGY (Total: 2541 journals)
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MICROBIOLOGY (200 journals)                  1 2     

Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (6 followers)
Addiction Genetics     Open Access   (2 followers)
Advances in Applied Microbiology     Full-text available via subscription   (11 followers)
Advances in Microbiology     Open Access   (11 followers)
Advances in Molecular Imaging     Open Access   (3 followers)
African Journal of Clinical and Experimental Microbiology     Open Access  
African Journal of Microbiology Research     Open Access  
American Journal of Infectious Diseases and Microbiology     Open Access   (8 followers)
American Journal of Microbiological Research     Open Access  
American Journal of Microbiology     Open Access   (12 followers)
American Journal of Molecular Biology     Open Access   (2 followers)
American Journal of Stem Cell Research     Open Access   (1 follower)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (4 followers)
Annals of Microbiology     Hybrid Journal   (6 followers)
Annual Review of Microbiology     Full-text available via subscription   (18 followers)
Antimicrobial Agents and Chemotherapy     Full-text available via subscription   (8 followers)
Applied and Environmental Microbiology     Full-text available via subscription   (20 followers)
Applied Biochemistry and Microbiology     Hybrid Journal   (6 followers)
Applied Microbiology and Biotechnology     Hybrid Journal   (22 followers)
Archives of Microbiology     Hybrid Journal   (3 followers)
Beneficial Microbes     Full-text available via subscription   (2 followers)
Bio-Research     Full-text available via subscription  
Biomaterials Science     Full-text available via subscription   (3 followers)
Biomedical Research     Open Access   (3 followers)
BioMolecular Concepts     Full-text available via subscription   (2 followers)
Biomolecules     Open Access   (1 follower)
BMC Microbiology     Open Access   (5 followers)
Brazilian Journal of Microbiology     Open Access   (1 follower)
Canadian Journal of Infectious Diseases & Medical Microbiology     Full-text available via subscription  
Canadian Journal of Microbiology     Full-text available via subscription   (3 followers)
Cell Biology : Research & Therapy     Partially Free  
Cell Host & Microbe     Full-text available via subscription   (4 followers)
Cell Medicine     Open Access  
Cell Regeneration     Open Access  
Cells     Open Access  
Cellular & Molecular Immunology     Hybrid Journal   (6 followers)
Cellular Microbiology     Hybrid Journal   (4 followers)
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (1 follower)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (9 followers)
Clinical Microbiology Newsletter     Hybrid Journal   (2 followers)
Clinical Microbiology Reviews     Full-text available via subscription   (9 followers)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (7 followers)
Computational Molecular Bioscience     Open Access  
Continental Journal of Microbiology     Open Access   (3 followers)
Critical Reviews in Microbiology     Hybrid Journal   (4 followers)
Current Microbiology     Hybrid Journal   (2 followers)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (11 followers)
Current Tissue Engineering     Hybrid Journal   (1 follower)
Current Topics in Microbiology and Immunology     Hybrid Journal   (1 follower)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (2 followers)
Disease and Molecular Medicine     Open Access   (1 follower)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (1 follower)
Environmental Microbiology     Hybrid Journal   (5 followers)
Environmental Microbiology Reports     Hybrid Journal   (3 followers)
Enzyme and Microbial Technology     Hybrid Journal   (5 followers)
Epigenetics of Degenerative Diseases     Open Access  
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (7 followers)
European Journal of Microbiology and Immunology     Open Access   (5 followers)
Experimental and Molecular Pathology     Hybrid Journal  
Fems Immunology & Medical Microbiology     Hybrid Journal   (6 followers)
Fems Microbiology Ecology     Hybrid Journal   (6 followers)
Fems Microbiology Letters     Hybrid Journal   (12 followers)
Fems Microbiology Reviews     Hybrid Journal   (15 followers)
Folia Microbiologica     Hybrid Journal   (1 follower)
Food Microbiology     Hybrid Journal   (10 followers)
Frontiers in Cell and Developmental Biology     Open Access   (1 follower)
Frontiers in Cellular and Infection Microbiology     Open Access   (1 follower)
Frontiers in Microbiology     Open Access   (2 followers)
Future Microbiology     Full-text available via subscription  
Future Virology     Full-text available via subscription   (3 followers)
Gene Expression     Full-text available via subscription  
Genetica si Biologie Moleculara     Open Access   (1 follower)
Genetics and Molecular Research     Open Access   (1 follower)
Geomicrobiology Journal     Hybrid Journal   (1 follower)
Gut Microbes     Full-text available via subscription  
Indian Journal of Microbiology     Hybrid Journal   (1 follower)
Indian Journal of Pathology and Microbiology     Open Access   (1 follower)
Infection Ecology & Epidemiology     Open Access   (5 followers)
International Arabic Journal of Antimicrobial Agents     Open Access   (4 followers)
International Journal of Antimicrobial Agents     Hybrid Journal   (1 follower)
International Journal of Bacteriology     Open Access  
International Journal of Bioassays     Open Access   (5 followers)
International Journal of Biotechnology and Molecular Biology Research     Open Access  
International Journal of Food Microbiology     Hybrid Journal   (10 followers)
International Journal of Infection and Microbiology     Open Access   (1 follower)
International Journal of Medical Microbiology     Hybrid Journal   (4 followers)
International Journal of Systematic and Evolutionary Microbiology     Full-text available via subscription   (3 followers)
International Microbiology     Open Access   (1 follower)
Invertebrate Immunity     Open Access  
Iranian Journal of Microbiology     Open Access  
ISRN Cell Biology     Open Access   (2 followers)
ISRN Microbiology     Open Access   (2 followers)
ISRN Molecular Biology     Open Access   (1 follower)
Journal of Microbial & Biochemical Technology     Open Access   (1 follower)
Journal of Applied Microbiology     Hybrid Journal   (5 followers)
Journal of Basic Microbiology     Hybrid Journal   (2 followers)

        1 2     

International Journal of Food Microbiology    [12 followers]  Follow    
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0168-1605
     Published by Elsevier Homepage  [2556 journals]   [SJR: 1.386]   [H-I: 108]
  • Trichothecene genotypes and production profiles of Fusarium graminearum
           isolates obtained from barley cultivated in Argentina
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Eliana Castañares , Diana Ramirez Albuquerque , María Inés Dinolfo , Virginia Fernandez Pinto , Andrea Patriarca , Sebastián Alberto Stenglein
      Fusarium graminearum is one of the most important pathogens isolated from small cereal grains with Fusarium Head Blight symptoms. The presence of this fungus is often linked to the occurrence of several mycotoxins in barley and wheat. The aim of our study was to characterize trichothecene genotypes and production profiles of F. graminearum sensu stricto isolates obtained from barley grains in Argentina. A total of 110 F. graminearum s.s. isolates were analyzed by PCR assays to predict deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON), 3-acetyldeoxynivalenol (3-ADON) and nivalenol (NIV) production, and all isolates were found to belong to the same molecular 15-ADON genotype. Trichothecene production in autoclaved rice was analyzed by using gas chromatography (GC) and confirmed by GC–MS. Of the 110 isolates, 95% were able to produce DON, 71% produced 15-ADON, 63% 3-ADON and 52% NIV. With the exception of a single isolate, all isolates that produced NIV, also produced DON. However, the NIV production was very low, ranging from 0.13 to 0.30μg/g. Six different production profiles of DON and its acetyl-derivatives were detected, the predominant being simultaneous production of DON, 3-ADON and 15-ADON, followed by DON production, and DON and 15-ADON co-production. This work is the first attempt to characterize the trichothecene genotypes and production profiles of F. graminearum s.s. isolates from Argentinean barley.


      PubDate: 2014-04-16T11:06:45Z
       
  • Fate of Vibrio parahaemolyticus on shrimp after acidic electrolyzed water
           treatment
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Jing Jing Wang , Wen Shuo Sun , Meng Tong Jin , Hai Quan Liu , Weijia Zhang , Xiao Hong Sun , Ying Jie Pan , Yong Zhao
      The objective of this study was to investigate the fate of Vibrio parahaemolyticus on shrimp after acidic electrolyzed water (AEW) treatment during storage. Shrimp, inoculated with a cocktail of four strains of V. parahaemolyticus, were stored at different temperatures (4–30°C) after AEW treatment. Experimental data were fitted to modified Gompertz and Log-linear models. The fate of V. parahaemolyticus was determined based on the growth and survival kinetics parameters (lag time, λ; the maximum growth rate, μ max; the maximum growth concentration, D; the inactivation value, K) depending on the respective storage conditions. Moreover, real-time PCR was employed to study the population dynamics of this pathogen during the refrigeration temperature storage (10, 7, 4°C). The results showed that AEW treatment could markedly (p <0.05) decrease the growth rate (μ max) and extend the lag time (λ) during the post-treatment storage at 30, 25, 20 and 15°C, while it did not present a capability to lower the maximum growth concentration (D). AEW treatment increased the sensitivity of V. parahaemolyticus to refrigeration temperatures, indicated by a higher (p <0.05) inactivation value (K) of V. parahaemolyticus, especially for 10°C storage. The results also revealed that AEW treatment could completely suppress the proliferation of V. parahaemolyticus in combination with refrigeration temperature. Based on above analysis, the present study demonstrates the potential of AEW in growth inhibition or death acceleration of V. parahaemolyticus on seafood, hence to greatly reduce the risk of illness caused by this pathogen during post-treatment storage.


      PubDate: 2014-04-16T11:06:45Z
       
  • The prevalence and impact of Fusarium head blight pathogens and mycotoxins
           on malting barley quality in UK
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): L.K. Nielsen , D.J. Cook , S.G. Edwards , R.V. Ray
      Fusarium head blight (FHB) caused by Fusarium and Microdochium species can significantly affect the yield of barley grain as well as the quality and safety of malt and beer. The present study provides new knowledge on the impacts of the FHB pathogen complex on the malting and brewing quality parameters of naturally infected barley. Quantitative real-time PCR and liquid chromatography double mass spectrometry were used to quantify the predominant FHB pathogens and Fusarium mycotoxins, respectively, in commercially grown UK malting barley samples collected between 2007 and 2011. The predominant Fusarium species identified across the years were F. poae, F. tricinctum and F. avenaceum. Microdochium majus was the predominant Microdochium species in 2007, 2008, 2010 and 2011 whilst Microdochium nivale predominated in 2009. Deoxynivalenol and zearalenone quantified in samples collected between 2007 and 2009 were associated with F. graminearum and F. culmorum, whilst HT-2 and T-2, and nivalenol in samples collected between 2010 and 2011 correlated positively with F. langsethiae and F. poae, respectively. Analysis of the regional distribution and yearly variation in samples from 2010 to 2011 showed significant differences in the composition of the FHB species complex. In most regions (Scotland, the South and North of England) the harvest in 2010 had higher concentrations of Fusarium spp. than in 2011, although no significant difference was observed in the Midlands between the two years. Microdochium DNA was significantly higher in 2011 and in the North of England and Scotland compared to the South or Midlands regions. Pathogens of the FHB complex impacted negatively on grain yield and quality parameters. Thousand grain weight of malting barley was affected significantly by M. nivale and M. majus whilst specific weight correlated negatively with F. avenaceum and F. graminearum. To determine the impact of sub-acute infections of the identified Fusarium and Microdochium species on malting and brewing quality of naturally infected samples, selected malting barley cultivars (Optic, Quench and Tipple) were micromalted and subjected to malt and wort analysis of key quality parameters. F. poae and M. nivale decreased germinative energy and increased water sensitivity of barley. The fungal biomass of F. poae and F. langsethiae correlated with increased wort free amino nitrogen and with decreased extract of malt. DNA of M. nivale correlated with increased malt friability as well as decreased wort filtration volume. The findings of this study indicate that the impact of species such as the newly emerging F. langsethiae, as well as F. poae and the two non-toxigenic Microdochium species should be considered when evaluating the quality of malting barley.


      PubDate: 2014-04-16T11:06:45Z
       
  • Automated immunomagnetic separation for the detection of Escherichia coli
           O157:H7 from spinach
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Jing Chen , Xianming Shi , Andrew G. Gehring , George C. Paoli
      Escherichia coli O157:H7 is a major cause of foodborne illness and methods for rapid and sensitive detection of this deadly pathogen are needed to protect consumers. The use of immunomagnetic separation (IMS) for capturing and detecting foodborne pathogens has gained popularity, partially due to the introduction of automated and high throughput IMS instrumentation. Three methods for automated IMS that test different sample volumes, Kingfisher® mL, Pathatrix® Auto, and Pathatrix® Ultra, were compared using microbiological detection of E. coli O157:H7 from buffered peptone water (BPW), in the presence of background microbial flora derived from spinach leaves, and from culture enrichments from artificially contaminated spinach leaves. The average efficiencies of capture of E. coli O157:H7 using the three methods were 32.1%, 3.7%, and 1.3%, respectively, in BPW; 43.4%, 8.8%, 2.9%, respectively, in the presence of spinach microbial flora; and 63.0%, 7.0%, and 6.3%, respectively, from artificially contaminated spinach. Despite the large differences in IMS capture efficiencies between the KingFisher® and two Pathatrix® methods, all three methods allowed the detection of E. coli O157:H7 from spinach that was artificially contaminated with the pathogen at relatively high (25cfu/30g sample) and low (1cfu/30g sample) levels after 4–6h of culture enrichment. The differences in capture efficiency were compensated for by the differences in sample volume used by the KingFisher® mL (1mL), Pathatrix® Auto (50mL) and Pathatrix® Ultra (250mL) instruments. Thus, despite the reduced capture efficiencies observed for the Pathatrix® methods, the large increase in sample volume results in a greater number of captured cells for downstream detection resulting in improved detection sensitivity.


      PubDate: 2014-04-11T10:48:03Z
       
  • Array based detection of antibiotic resistance genes in Gram negative
           bacteria isolated from retail poultry meat in the UK and Ireland
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Grainne McNeece , Violetta Naughton , Martin J. Woodward , James S.G. Dooley , Patrick J. Naughton
      The use of antibiotics in birds and animals intended for human consumption within the European Union (EU) and elsewhere has been subject to regulation prohibiting the use of antimicrobials as growth promoters and the use of last resort antibiotics in an attempt to reduce the spread of multi-resistant Gram negative bacteria. Given the inexorable spread of antibiotic resistance there is an increasing need for improved monitoring of our food. Using selective media, Gram negative bacteria were isolated from retail chicken of UK-Intensively reared (n =27), Irish-Intensively reared (n =19) and UK-Free range (n =30) origin and subjected to an oligonucleotide based array system for the detection of 47 clinically relevant antibiotic resistance genes (ARGs) and two integrase genes. High incidences of β-lactamase genes were noted in all sample types, acc (67%), cmy (80%), fox (55%) and tem (40%) while chloramphenicol resistant determinants were detected in bacteria from the UK poultry portions and were absent in bacteria from the Irish samples. Denaturing Gradient Gel Electrophoresis (DGGE) was used to qualitatively analyse the Gram negative population in the samples and showed the expected diversity based on band stabbing and DNA sequencing. The array system proved to be a quick method for the detection of antibiotic resistance gene (ARG) burden within a mixed Gram negative bacterial population.


      PubDate: 2014-04-11T10:48:03Z
       
  • Whole-head washing, prior to cutting, provides sanitization advantages for
           fresh-cut Iceberg lettuce (Latuca sativa L.)
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Sindy Palma-Salgado , Arne J. Pearlstein , Yaguang Luo , Hee Kyung Park , Hao Feng
      The efficacy of two leafy produce wash methods, the traditional cutting-before-washing process and a new washing-before-cutting method, on reduction of Escherichia coli O157:H7 inoculated on Iceberg lettuce was compared. The washing tests were conducted in a pilot-scale washer using combinations of water, chlorine, peroxyacetic acid, and ultrasound. The washing-before-cutting process recorded an E. coli O157:H7 count reduction 0.79–0.80 log10 CFU/g higher than that achieved with the cutting-before-washing process in treatments involving only a sanitizer. When ultrasound was applied to the washing-before-cutting process, a further improvement of 0.37–0.68 log10 CFU/g in microbial count reduction was obtained, reaching total reductions of 2.43 and 2.24 log10 CFU/g for chlorine and peroxyacetic acid washes, respectively.


      PubDate: 2014-04-06T06:52:37Z
       
  • Editorial Board
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178




      PubDate: 2014-04-06T06:52:37Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178




      PubDate: 2014-04-06T06:52:37Z
       
  • The influence of salt (NaCl) on ochratoxin A biosynthetic genes, growth
           and ochratoxin A production by three strains of Penicillium nordicum on a
           dry-cured ham-based medium
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Alicia Rodríguez , Ángel Medina , Juan J. Córdoba , Naresh Magan
      Iberian dry-cured ham is colonised by moulds during the ripening process. The environmental conditions occurring during the process including the salt content predisposes the surface to colonisation by Penicillium species, including Penicillium nordicum which can contaminate the curing ham with ochratoxin A (OTA). The objective of this study was to examine the effect of NaCl (10% and 22%=0.94 and 0.87 water activity (aw)) on the activation of two genes involved in the biosynthetic pathway for OTA production, otapksPN and otanpsPN, relative growth and phenotypic OTA production by three strains of P. nordicum (CBS 110.769, FHSCC1 and FHSCC2) on a ham-based medium over a period of 12days at 25°C. Growth of the three strains was faster at 0.87 than 0.94 aw on the ham-based media. However, some intra- and inter-strain differences were observed. Of the three strains, only two (CBS 110.789; FHSCC2) were able to express the two genes involved in the biosynthesis of OTA in the two salt treatments. RT-qPCR showed that the temporal expression of the two genes (otapksPN and otanpsPN) was relatively similar for the wild type strain (FHSCC2) at both 0.94 and 0.87 aw over the 12day period. However, in the type strain (CBS 110.769) expression increased rapidly at 0.94 aw but was significantly lower at 0.87 aw. Expression of these two genes occurred after 3day incubation, while phenotypic OTA production was observed only after 6days in the two toxigenic strains. The other strain did not produce any OTA. The OTA concentrations confirmed the results observed with the molecular tools. This suggests that the RT-qPCR gene expression of these two genes may be a good early indicator of potential contamination of dry-cured ham with OTA during dry-cured ham ripening.


      PubDate: 2014-04-01T06:16:51Z
       
  • Simple and rapid method for the detection of Filobasidiella neoformans in
           
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Hiroshi Ishikawa , Kohei Kasahara , Sumie Sato , Yasuhisa Shimakawa , Koichi Watanabe
      Yeast contamination is a serious problem in the food industry and a major cause of food spoilage. Several yeasts, such as Filobasidiella neoformans, which cause cryptococcosis in humans, are also opportunistic pathogens, so a simple and rapid method for monitoring yeast contamination in food is essential. Here, we developed a simple and rapid method that utilizes loop-mediated isothermal amplification (LAMP) for the detection of F. neoformans. A set of five specific LAMP primers was designed that targeted the 5.8S–26S rDNA internal transcribed spacer 2 region of F. neoformans, and the primer set's specificity was confirmed. In a pure culture of F. neoformans, the LAMP assay had a lower sensitivity threshold of 102 cells/mL at a runtime of 60min. In a probiotic dairy product artificially contaminated with F. neoformans, the LAMP assay also had a lower sensitivity threshold of 102 cells/mL, which was comparable to the sensitivity of a quantitative PCR (qPCR) assay. We also developed a simple two-step method for the extraction of DNA from a probiotic dairy product that can be performed within 15min. This method involves initial protease treatment of the test sample at 45°C for 3min followed by boiling at 100°C for 5min under alkaline conditions. In a probiotic dairy product artificially contaminated with F. neoformans, analysis by means of our novel DNA extraction method followed by LAMP with our specific primer set had a lower sensitivity threshold of 103 cells/mL at a runtime of 60min. In contrast, use of our novel method of DNA extraction followed by qPCR assay had a lower sensitivity threshold of only 105 cells/mL at a runtime of 3 to 4h. Therefore, unlike the PCR assay, our LAMP assay can be used to quickly evaluate yeast contamination and is sensitive even for crude samples containing bacteria or background impurities. Our study provides a powerful tool for the primary screening of large numbers of food samples for yeast contamination.


      PubDate: 2014-04-01T06:16:51Z
       
  • Acetic acid bacteria isolated from grapes of South Australian vineyards
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): E. Mateo , M.J. Torija , A. Mas , E.J. Bartowsky
      Acetic acid bacteria (AAB) diversity from healthy, mould-infected and rot-affected grapes collected from three vineyards of Adelaide Hills (South Australia) was analyzed by molecular typing and identification methods. Nine different AAB species were identified from the 624 isolates recovered: Four species from Gluconobacter genus, two from Asaia and one from Acetobacter were identified by the analysis of 16S rRNA gene and 16S–23S rRNA gene internal transcribed spacer. However, the identification of other isolates that were assigned as Asaia sp. and Ameyamaea chiangmaiensis required more analysis for a correct species classification. The species of Gluconobacter cerinus was the main one identified; while one genotype of Asaia siamensis presented the highest number of isolates. The number of colonies recovered and genotypes identified was strongly affected by the infection status of the grapes; the rot-affected with the highest number. However, the species diversity was similar in all the cases. High AAB diversity was detected with a specific genotype distribution for each vineyard.


      PubDate: 2014-04-01T06:16:51Z
       
  • Identification and characterization of the polyketide synthase involved in
           ochratoxin A biosynthesis in Aspergillus carbonarius
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Antonia Gallo , Benjamin P. Knox , Kenneth S. Bruno , Michele Solfrizzo , Scott E. Baker , Giancarlo Perrone
      Ochratoxin A (OTA) is a potent mycotoxin produced by Aspergillus and Penicillium species and is a common contaminant of a wide variety of food commodities, with Aspergillus carbonarius being the main producer of OTA contamination in grapes and wine. The molecular structure of OTA comprises a dihydroisocoumarin ring linked to phenylalanine and, as shown in different producing fungal species, a polyketide synthase (PKS) is a component of the OTA biosynthetic pathway. Similar to observations in other filamentous ascomycetes, the genome sequence of A. carbonarius contains a large number of genes predicted to encode PKSs. In this work a pks gene identified within the putative OTA cluster of A. carbonarius, designated as AcOTApks, was inactivated and the resulting mutant strain was unable to produce OTA, confirming the role of AcOTApks in this biosynthetic pathway. AcOTApks protein is characteristic of the highly reduced (HR)-PKS family, and also contains a putative methyltransferase domain likely responsible for the addition of the methyl group to the OTA polyketide structure. AcOTApks is different from the ACpks protein that we previously described in A. carbonarius, which showed an expression profile compatible with OTA production. We performed phylogenetic analyses of the β-ketosynthase and acyl-transferase domains of the OTA PKSs that had been identified and characterized in different OTA producing fungal species. The phylogenetic results were similar for both domains analyzed and showed that OTA PKS of A. carbonarius, Aspergillus niger and Aspergillus ochraceus clustered in a monophyletic group with 100% bootstrap support suggesting a common origin, while the other OTA PKSs analyzed were phylogenetically distant. A quantitative RT-PCR assay monitored AcOTApks expression during fungal growth and concomitant production of OTA by A. carbonarius in synthetic grape medium. A clear correlation between the expression profile of AcOTApks and kinetics of OTA production was observed, with AcOTApks reaching its maximum level of transcription before OTA accumulation in mycelium reached its highest level, confirming the fact that gene transcription always precedes phenotypic production.


      PubDate: 2014-04-01T06:16:51Z
       
  • Oenological prefermentation practices strongly impact yeast population
           dynamics and alcoholic fermentation kinetics in Chardonnay grape must
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Warren Albertin , Cécile Miot-Sertier , Marina Bely , Philippe Marullo , Joana Coulon , Virginie Moine , Benoit Colonna-Ceccaldi , Isabelle Masneuf-Pomarede
      Yeast species of Hanseniaspora and Candida genus are predominant during the early stages of winemaking, while species of Metschnikowia, Pichia, Zygoascus, Issatchenkia, Torulaspora and other genera are present at lower population levels. The impact of common oenological practices on yeast dynamics during the prefermentative stage and the early stage of alcoholic fermentation (AF) remains elusive. In this work, the effect of four prefermentative oenological practices (clarification degree, temperature, sulphite and starter yeast addition) on yeast dynamics was evaluated in a Chardonnay grape must. The growth curves of four genus or species, namely Saccharomyces spp., Hanseniaspora spp., Candida zemplinina and Torulaspora delbrueckii, were followed by quantitative PCR. The fermentation kinetics were also recorded, as well as the production of acetic acid. Variance analysis allowed determining the effect of each practice and their interaction factors, as well as their relative importance on yeast dynamics and fermentation kinetics. Our experimental design showed that the population dynamics of the four species were differently impacted by the oenological practices, with some species being more sensitive than others to the clarification degree (C. zemplinina), sulphite addition (Saccharomyces spp.), starter yeast inoculation (Hanseniaspora spp.) or prefermentation temperature (T. delbrueckii). Significant interaction effects between practices were revealed, highlighting the interest of experimental design allowing interaction analysis, as some factors may buffer the effect of other ones. Hanseniaspora genus showed atypical behaviour: growth dynamics showed a decrease during AF that we interpreted as early cellular lysis. In conclusion, this study provides new insights on the impact of common oenological practices on the dynamics of non-Saccharomyces yeast that will be useful for a better management of mixed fermentation between S. cerevisiae and non-Saccharomyces yeasts.


      PubDate: 2014-04-01T06:16:51Z
       
  • Optimization of combinations of bactericidal and bacteriostatic treatments
           to control Listeria monocytogenes on cold-smoked salmon
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Jihun Kang , Matthew J. Stasiewicz , Dillon Murray , Kathryn J. Boor , Martin Wiedmann , Teresa M. Bergholz
      Contamination of cold-smoked salmon by Listeria monocytogenes is a major concern for the seafood industry. The objectives of this study were to (i) determine the most effective bactericidal treatment for L. monocytogenes on salmon and (ii) optimize bactericidal and bacteriostatic treatment combinations to identify cost-effective treatments against L. monocytogenes on salmon. L. monocytogenes challenge trials were conducted in brain heart infusion (BHI) and on salmon disks that were supplemented with bactericidal compounds nisin (NIS), lauric arginate (LAE), ε-polylysine (EPL), and chitosan (CHIT). Subsequently, the most effective bactericidal compound was further tested by concurrent application of a blend of organic acid salts containing potassium lactate and sodium diacetate (PLSDA). L. monocytogenes populations were measured at 7°C over 60days, and initial cell density (N 0), maximum initial log reduction (N r), lag phase (λ), maximum growth rate (μmax), and maximum cell density (N max) over 60days storage were estimated. Time to recover to initial cell density (T initial) was also compared for combinations of bactericidal and bacteriostatic treatments. Varying degrees of antimicrobial effects were observed with bactericidal compounds in BHI. However, when tested on salmon, only NIS significantly decreased initial L. monocytogenes populations by approximately 2logCFU/g, and reduced N max by approximately 1.5logCFU/g compared to untreated control (CTRL). N r achieved by the combined treatment of NIS and PLSDA was approximately 2logCFU/g regardless of the presence of PLSDA, and a dose-dependent increase in N r was observed with increasing NIS concentrations. PLSDA alone or in combination with 20ppm NIS was most effective at delaying growth of L. monocytogenes. The greatest reduction in N max was observed with the combination of 20ppm NIS and PLSDA; N max was 3.1logCFU/g lower compared to CTRL. Comparison of T initial indicated that PLSDA with NIS can effectively retard growth of L. monocytogenes to its initial level (following initial reduction) and offers a cost benefit over using high concentrations of NIS alone. In summary, the combined application of NIS (for a bactericidal effect) and PLSDA (for a bacteriostatic effect) proved to be an effective treatment option to reduce initial levels as well as minimize subsequent growth of L. monocytogenes throughout the expected shelf-life of cold-smoked salmon.


      PubDate: 2014-04-01T06:16:51Z
       
  • Spoilage potential of psychrotrophic lactic acid bacteria (LAB) species:
           Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, on sweet
           bell pepper (SBP) simulation medium under different gas compositions
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Vasileios Pothakos , Clarice Nyambi , Bao-Yu Zhang , Antonios Papastergiadis , Bruno De Meulenaer , Frank Devlieghere
      Sweet bell peppers are a significant constituent of retail, chilled-stored and packaged food products like fresh salads, marinades and ready-to-eat (RTE) meals. Previously, through general screening of the Belgian market and by means of source tracking analysis in a plant manufacturing minimally processed, vegetable salads the susceptibility of fresh-cut sweet bell peppers to lactic acid bacterium (LAB) contamination was substantiated. The determination of the metabolic profiles of Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, two major psychrotrophic, spoilage-related LAB species, on sweet bell pepper (SBP) simulation medium under different packaging conditions – 1.) vacuum: 100% N2, 2.) air: 21% O2, 79% N2, 3.) MAP1: 30% CO2, 70% N2 and 4.) MAP2: 50% O2, 50% CO2 – facilitated a better understanding of the spoilage potential of these microbes as well as the presumptive contribution of O2 in the spectrum of produced volatile organic compounds (VOCs) associated with poor organoleptic properties of food products. Generally, none of the applied gas compositions inhibited the growth of the 4 L. gelidum subsp. gasicomitatum isolates, however the presence of O2 resulted in buttery off-odors by inducing primarily the accumulation of diacetyl and pungent “vinegar” smell due to acetic acid. The 3 tested isolates of L. piscium varied greatly among their growth dynamics and inhibition at MAP2. They exhibited either weak spoilage profile or very offensive metabolism confirming significant intraspecies diversity.


      PubDate: 2014-04-01T06:16:51Z
       
  • Acidification of apple and orange hosts by Penicillium digitatum and
           Penicillium expansum
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): L. Vilanova , I. Viñas , R. Torres , J. Usall , G. Buron-Moles , N. Teixidó
      New information about virulence mechanisms of Penicillium digitatum and Penicillium expansum could be an important avenue to control fungal diseases. In this study, the ability of P. digitatum and P. expansum to enhance their virulence by locally modulating the pH of oranges and apples was evaluated. For each host, pH changes with a compatible pathogen and a non-host pathogen were recorded, and the levels of different organic acids were evaluated to establish possible relationships with host pH modifications. Moreover, fruits were harvested at three maturity stages to determine whether fruit maturity could affect the pathogens' virulence. The pH of oranges and apples decreased when the compatible pathogens (P. digitatum and P. expansum, respectively) decayed the fruit. The main organic acid detected in P. digitatum-decayed oranges was galacturonic acid produced as a consequence of host maceration in the rot development process. However, the obtained results showed that this acid was not responsible for the pH decrease in decayed orange tissue. The mixture of malic and citric acids could at least contribute to the acidification of P. digitatum-decayed oranges. The pH decrease in P. expansum decayed apples is related to the accumulation of gluconic and fumaric acids. The pH of oranges and apples was not affected when the non-host pathogen was not able to macerate the tissues. However, different organic acid contents were detected in comparison to healthy tissues. The main organic acids detected in P. expansum–oranges were oxalic and gluconic and in P. digitatum–apples were citric, gluconic and galacturonic. Further research is needed to identify the pathogenicity factors of both fungi because the contribution of organic acids has profound implications.


      PubDate: 2014-03-27T07:27:26Z
       
  • Kefir fermented milk and kefiran promote growth of Bifidobacterium bifidum
           PRL2010 and modulate its gene expression
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Fausta Serafini , Francesca Turroni , Patricia Ruas-Madiedo , Gabriele Andrea Lugli , Christian Milani , Sabrina Duranti , Nicole Zamboni , Francesca Bottacini , Douwe van Sinderen , Abelardo Margolles , Marco Ventura
      Bifidobacteria constitute one of the dominant groups of microorganisms colonizing the human gut of infants. Their ability to utilize various host-derived glycans as well as dietary carbohydrates has received considerable scientific attention. However, very little is known about the role of fermented foods, such as kefir, or their constituent glycans, such as kefiran, as substrates for bifidobacterial growth and for the modulation of the expression of bifidobacterial host-effector molecules. Here, we show that Bifidobacterium bifidum PRL2010 exhibits high growth performance among the bifidobacterial strains tested when cultivated on kefir and/or kefiran polymer. Furthermore, a 16S rRNA metagenomic approach revealed that the microbiota of kefir is modified upon the addition of PRL2010 cells to the kefir matrix. Finally, our results show that kefir and kefiran are able to influence the transcriptome of B. bifidum PRL2010 causing increased transcription of genes involved in the metabolism of dietary glycans as well as genes that act as host–microbe effector molecules such as pili. Altogether, these data support the use of kefir as a valuable means for the delivery of effective microbial cells in probiotic therapy.


      PubDate: 2014-03-27T07:27:26Z
       
  • Fungi and mycotoxins in cocoa: From farm to chocolate
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Marina V. Copetti , Beatriz T. Iamanaka , John I. Pitt , Marta H. Taniwaki
      Cocoa is an important crop, as it is the raw material from which chocolate is manufactured. It is grown mainly in West Africa although significant quantities also come from Asia and Central and South America. Primary processing is carried out on the farm, and the flavour of chocolate starts to develop at that time. Freshly harvested pods are opened, the beans, piled in heaps or wooden boxes, are fermented naturally by yeasts and bacteria, then dried in the sun on wooden platforms or sometimes on cement or on the ground, where a gradual reduction in moisture content inhibits microbial growth. Beans are then bagged and marketed. In processing plants, the dried fermented beans are roasted, shelled and ground, then two distinct processes are used, to produce powdered cocoa or chocolate. Filamentous fungi may contaminate many stages in cocoa processing, and poor practices may have a strong influence on the quality of the beans. Apart from causing spoilage, filamentous fungi may also produce aflatoxins and ochratoxin A. This review deals with the growth of fungal species and formation of mycotoxins during the various steps in cocoa processing, as well as reduction of these contaminants by good processing practices. Methodologies for fungal and mycotoxin detection and quantification are discussed while current data about dietary exposure and regulation are also presented.


      PubDate: 2014-03-27T07:27:26Z
       
  • Active polymers containing Lactobacillus curvatus CRL705 bacteriocins:
           Effectiveness assessment in Wieners
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): M. Blanco Massani , V. Molina , M. Sanchez , V. Renaud , P. Eisenberg , G. Vignolo
      Bacteriocins from lactic acid bacteria have potential as natural food preservatives. In this study two active (synthetic and gluten) films were obtained by the incorporation of lactocin 705 and lactocin AL705, bacteriocins produced by Lactobacillus curvatus CRL705 with antimicrobial activity against spoilage lactic acid bacteria and Listeria. Antimicrobial film effectiveness was determined in Wieners inoculated with Lactobacillus plantarum CRL691 and Listeria innocua 7 (104 CFU/g) stored at 5°C during 45days. Active and control (absence of bacteriocins) packages were prepared and bacterial counts in selective media were carried out. Visual inspection and pH measurement of Wieners were also performed. Typical growth of both inoculated microorganisms was observed in control packages which reached 106–107 CFU/g at the end of storage period. In the active packages, L. innocua 7 was effectively inhibited (2.5 log cycles reduction at day 45), while L. plantarum CRL691 was only slightly inhibited (0.5 log cycles) up to the second week of storage, then counts around 106–107 CFU/g were reached. Changes in pH values from 6.3 to 5.8 were produced and gas formation was observed in active and control packages. The low inhibitory effectiveness against lactic acid bacteria is in correlation with the low activity observed for lactocin 705 in the presence of fat; Wieners fat content (20–30%) may adversely affect antimicrobial activity. This study supports the feasibility of using polymers activated with L. curvatus CRL705 bacteriocins to control Listeria on the surface of Wieners and highlights the importance of evaluating antimicrobial packaging systems for each particular food application.


      PubDate: 2014-03-27T07:27:26Z
       
  • Acid stress management by Cronobacter sakazakii
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Avelino Alvarez-Ordóñez , Conor Cummins , Thérèse Deasy , Tanya Clifford , Máire Begley , Colin Hill
      Cronobacter sakazakii is a foodborne pathogenic microorganism associated with sporadic cases of neonatal meningitis, necrotising enterocolitis, septicaemia, bloody diarrhoea and brain abscesses acquired through the consumption of contaminated powdered infant formula (PIF). This study aimed to investigate the growth of C. sakazakii DPC6529, a particularly stress tolerant clinical isolate, in acidified laboratory media and PIF. The possibility of a stationary-phase acid tolerance response (ATR) was also investigated. C. sakazakii DPC6529 grew in LB broth acidified to pH4.2 with hydrochloric acid (HCl) and was capable of relatively fast growth in PIF acidified to pH5.0 with HCl, representing the stomach pH reported for newborns and infants. Moreover, bacterial growth in LB broth supplemented with 1% (w/v) glucose gave rise to a stationary-phase ATR which resulted in enhanced survival against a subsequent acid challenge at pH3.0. A transposon mutagenesis approach was used to shed light on some of the molecular mechanisms involved in the response C. sakazakii DPC6529 to normally lethal acid exposures. The data suggests that repairing damage in proteins and nucleic acids, posttranscriptional modification of tRNA molecules and maintenance of the integrity of the cellular envelope are key processes in the defence against acid stress. Clones carrying transposon insertions in genes encoding the envelope stress response regulators CpxR and OmpR were identified as acid-sensitive mutants. Further analyses of the ompR defective mutant and its complemented counterpart evidenced that OmpR is a key player in the response of C. sakazakii to acid stress, although it was not essential to mount an active stationary-phase ATR, at least under the tested conditions. The ability of C. sakazakii DPC6529 to grow in acid environments and to develop an adaptive stationary-phase ATR may allow for its survival or even proliferation within the infant gastrointestinal tract after consumption of contaminated milk formulae.


      PubDate: 2014-03-27T07:27:26Z
       
  • Genetic diversity and antibiotic resistance profiles of Campylobacter
           jejuni isolates from poultry and humans in Turkey
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Secil Abay , Tuba Kayman , Baris Otlu , Harun Hizlisoy , Fuat Aydin , Nurhan Ertas
      In this study, the investigation of clonal relations between human and poultry Campylobacter jejuni isolates and the determination of susceptibilities of isolates to various antibiotics were aimed. A total of 200 C. jejuni isolates concurrently obtained from 100 chicken carcasses and 100 humans were genotyped by the Pulsed-Field Gel Electrophoresis (PFGE) and automated Repetitive Extragenic Palindromic PCR (Rep-PCR, DiversiLab system) methods and were tested for their susceptibility to six antibiotics with disk diffusion method. The minimum inhibitory concentration (MIC) values of ciprofloxacin (CI), enrofloxacin (EF) and erythromycin (EM) were evaluated by E-test. By using PFGE 174 of (87.0%) the isolates were able to be typed. The clonally related strains were placed in 35 different clusters and 115 different genotypes were obtained. All of the two hundred isolates could be typed by using Rep-PCR and were divided into 133 different genotypes. One hundred and fourteen clonally related isolates (57.0%) were included in 47 clusters. In disk diffusion test, while the susceptibility rates of AMC and S to human and chicken derived C. jejuni isolates were 84.0%–96.0% and 96.0%–98.0%, respectively, all isolates were susceptible to gentamicin. The resistance rates of human isolates to AMP, NA and TE were detected as 44.0%, 84.0% and 38.0% of the resistances of chicken isolates to these antibiotics were 34.0%, 95.0% and 56.0%, respectively. The MIC values of human and chicken isolates to CI, EF and EM were detected as 81.0–93.0%, 85.0–88.0% and 6.0–7.0%, respectively. The clonal proximity rates were detected between human and poultry origin C. jejuni isolates. The discriminatory power of PFGE and Rep-PCR was similar, with Simpson's diversity indexes of 0.993 and 0.995, respectively. Concordance of the two methods as determined by Adjusted Rand coefficient was 0.198 which showed the low congruence between Rep-PCR and PFGE. High rates of quinolone resistance were detected in C. jejuni isolates. This study demonstrated that chicken meat played an important role for infections caused by C. jejuni in Turkey and erythromycin, amoxicillin clavulanic acid and gentamicin are recommended for the treatment of Campylobacteriosis in humans.


      PubDate: 2014-03-27T07:27:26Z
       
  • Editorial Board
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177




      PubDate: 2014-03-27T07:27:26Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177




      PubDate: 2014-03-27T07:27:26Z
       
  • Anaerobic organic acid metabolism of Candida zemplinina in comparison with
           Saccharomyces wine yeasts
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Ildikó Magyar , Diána Nyitrai-Sárdy , Annamária Leskó , Andrea Pomázi , Miklós Kállay
      Organic acid production under oxygen-limited conditions has been thoroughly studied in the Saccharomyces species, but practically never investigated in Candida zemplinina, which seems to be an acidogenic species under oxidative laboratory conditions. In this study, several strains of C. zemplinina were tested for organic acid metabolism, in comparison with Saccharomyces cerevisiae, Saccharomyces uvarum and Candida stellata, under fermentative conditions. Only C. stellata produced significantly higher acidity in simple minimal media (SM) with low sugar content and two different nitrogen sources (ammonia or glutamic acid) at low level. However, the acid profile differed largely between the Saccharomyces and Candida species and showed inverse types of N-dependence in some cases. Succinic acid production was strongly enhanced on glutamic acid in Saccharomyces species, but not in Candida species. 2-oxoglutarate production was strongly supported on ammonium nitrogen in Candida species, but remained low in Saccharomyces. Candida species, C. stellata in particular, produced more pyruvic acid regardless of N-sources. From the results, we concluded that the anaerobic organic acid metabolisms of C. zemplinina and C. stellata are different from each other and also from that of the Saccharomyces species. In the formation of succinic acid, the oxidative pathway from glutamic acid seems to play little or no role in C. zemplinina. The reductive branch of the TCA cycle, however, produces acidic intermediates (malic, fumaric, and succinic acid) in a level comparable with the production of the Saccharomyces species. An unidentified organic acid, which was produced on glutamic acid only by the Candida species, needs further investigation.


      PubDate: 2014-03-27T07:27:26Z
       
  • Presence, viral load and characterization of Torque teno sus viruses in
           liver and pork chop samples at retail
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Danielle Leblanc , Alain Houde , Marie-Josée Gagné , Daniel Plante , Pascale Bellon-Gagnon , Tineke H. Jones , Victoria Muehlhauser , Barbara Wilhelm , Brent Avery , Nicol Janecko , Julie Brassard
      Torque teno viruses (TTV) are widespread in humans, swine as well as in several other animal species. In market ready swine, the reported prevalence ranges between 11% and 100%. Through a national retail sampling plan from the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) program, 283 and 599 liver and pork chop samples, respectively, were collected over a 12-month period from commercial establishments in 5 selected geographical regions of Canada to assess the presence of Torque teno sus viruses (TTSuVs) in these products. TTSuVs were detected in 97.9% of pork chops with viral loads ranging between 1×104 and 9.9×105 genomic copies (gc)/g and 98.6% of liver samples with viral loads ranging from 1×105 to 9.9×106 gc/g. A selection of 20 positive samples (10 pork chop and 10 liver) from the 5 geographical regions were further tested for the production, of a 305bp fragment for TTSuV1 and a 253bp fragment for TTSuV2 in the non-coding region. TTSuV1 was present in all 10 liver and 10 pork chops samples while TTSuV2 was detected in 10 liver and 9 pork chop samples. Two different TTSuV1 sequences were simultaneously detected from 5 of 20 samples and 2 different TTSuV2 sequences were detected from 6 of 19 samples. The omnipresence of TTSuVs in commercial pork samples may allow its use as a viral indicator to monitor the effectiveness of cleaning and disinfecting process in slaughtering, cutting, slicing and packaging facilities.


      PubDate: 2014-03-27T07:27:26Z
       
  • Transcription profiling of interactions between Lactococcus lactis subsp.
           cremoris SK11 and Lactobacillus paracasei ATCC 334 during Cheddar cheese
           simulation
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): Émilie Desfossés-Foucault , Gisèle LaPointe , Denis Roy
      The starter cultures (Lactococcus sp.) and non-starter lactic acid bacteria (mostly Lactobacillus spp.) are essential to flavor development of Cheddar cheese. The aim of this study was to elucidate the transcriptional interaction between Lactococcus lactis subsp. cremoris SK11 and Lactobacillus paracasei ATCC 334 in mixed cultures during simulated Cheddar cheese manufacture (Pearce activity test) and ripening (slurry). Reverse transcription quantitative PCR (RT-qPCR) was used to quantify the expression of 34 genes common to both bacteria and for eight genes specific to either L. lactis subsp. cremoris SK11 or L. paracasei ATCC 334. The multifactorial analysis (MFA) performed on fold change results for each gene revealed that the genes linked to stress, protein and peptide degradation as well as carbohydrate metabolism of L. paracasei ATCC 334 were especially overexpressed in mixed culture with L. lactis subsp. cremoris SK11 during the ripening simulation. For L. lactis subsp. cremoris SK11, genes coding for amino acid metabolism were more expressed during the cheese manufacture simulation, especially in single culture. These results show how complementary functions of starter and NSLAB contribute to activities useful for flavor development.


      PubDate: 2014-03-27T07:27:26Z
       
  • Storage of pork meat under modified atmospheres containing vapors from
           commercial alcoholic beverages
    • Abstract: Publication date: 16 May 2014
      Source:International Journal of Food Microbiology, Volume 178
      Author(s): A.E. Kapetanakou , E.I. Agathaggelou , P.N. Skandamis
      The present study aimed to evaluate the effect of AB vapors on microbial, physicochemical, and sensory profile of pork meat stored in different MAP conditions. Pork pieces (10g) and cotton/cellulose absorbent cloths (2×2cm) were placed into compartmentalized Petri-dishes in two sections. Aliquots (1mL) of water (control), 30% v/v and 40% v/v ethanol, whisky, brandy, tsipouro, raki, and ouzo were added separately to the cotton/cellulose absorbent cloths. Each pork sample was placed in one compartment and cotton/cellulose absorbent cloths supplemented with different ABs were placed in a separate compartment of each Petri-dish. Samples were packaged in 40% CO2: 30% O2: 30% N2 and 80% O2: 20% CO2 and stored at 4 and 10°C. Total viable counts, Pseudomonas sp., Brochothrix thermosphacta, lactic acid bacteria, yeasts and molds, and Enterobacteriaceae, were enumerated during storage. Changes in pH, color (L*, a*, b*), odor, taste, and overall appearance of pork meat were also evaluated along with changes in organic acid levels via HPLC. At 4°C, lactic acid bacteria and B. thermosphacta were the dominant organisms under 40% CO2: 30% N2: 30% O2 and 80% O2: 20% CO2, respectively, while at 10°C, lactic acid bacteria dominated in both MAP conditions. All applied ABs were effective (p<0.05) against lactic acid bacteria, pseudomonads, and B. thermosphacta. The inhibitory effect of ABs was also reflected through lower levels of glucose consumption or accumulation of lactic, acetic, succinic, and formic acid compared to controls. Moreover, packaged samples in 40% CO2: 30% O2: 30% N2 exhibited a significant increase (p<0.05) of acetic acid during storage at 4°C, but the concentrations of acetic acid in samples exposed to AB vapors were lower than those in controls. Both antimicrobial active MAPs extended the shelf-life of pork meat by ca. 2-fold, while samples exposed to alcoholic beverages (especially ouzo) under 80% O2: 20% CO2 resulted in better (p<0.05) sensory properties compared to the respective samples under 40% CO2: 30% O2: 30% N2. Overall, vapor action of ABs in combination with MAP may constitute a promising, antimicrobial packaging technology for extending the shelf-life of pork meat.


      PubDate: 2014-03-27T07:27:26Z
       
  • Traditional cheeses: Rich and diverse microbiota with associated benefits
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Marie-Christine Montel , Solange Buchin , Adrien Mallet , Céline Delbes-Paus , Dominique A. Vuitton , Nathalie Desmasures , Françoise Berthier
      The risks and benefits of traditional cheeses, mainly raw milk cheeses, are rarely set out objectively, whence the recurrent confused debate over their pros and cons. This review starts by emphasizing the particularities of the microbiota in traditional cheeses. It then describes the sensory, hygiene, and possible health benefits associated with traditional cheeses. The microbial diversity underlying the benefits of raw milk cheese depends on both the milk microbiota and on traditional practices, including inoculation practices. Traditional know-how from farming to cheese processing helps to maintain both the richness of the microbiota in individual cheeses and the diversity between cheeses throughout processing. All in all more than 400 species of lactic acid bacteria, Gram and catalase-positive bacteria, Gram-negative bacteria, yeasts and moulds have been detected in raw milk. This biodiversity decreases in cheese cores, where a small number of lactic acid bacteria species are numerically dominant, but persists on the cheese surfaces, which harbour numerous species of bacteria, yeasts and moulds. Diversity between cheeses is due particularly to wide variations in the dynamics of the same species in different cheeses. Flavour is more intense and rich in raw milk cheeses than in processed ones. This is mainly because an abundant native microbiota can express in raw milk cheeses, which is not the case in cheeses made from pasteurized or microfiltered milk. Compared to commercial strains, indigenous lactic acid bacteria isolated from milk/cheese, and surface bacteria and yeasts isolated from traditional brines, were associated with more complex volatile profiles and higher scores for some sensorial attributes. The ability of traditional cheeses to combat pathogens is related more to native antipathogenic strains or microbial consortia than to natural non-microbial inhibitor(s) from milk. Quite different native microbiota can protect against Listeria monocytogenes in cheeses (in both core and surface) and on the wooden surfaces of traditional equipment. The inhibition seems to be associated with their qualitative and quantitative composition rather than with their degree of diversity. The inhibitory mechanisms are not well elucidated. Both cross-sectional and cohort studies have evidenced a strong association of raw-milk consumption with protection against allergic/atopic diseases; further studies are needed to determine whether such association extends to traditional raw-milk cheese consumption. In the future, the use of meta-omics methods should help to decipher how traditional cheese ecosystems form and function, opening the way to new methods of risk–benefit management from farm to ripened cheese.


      PubDate: 2014-03-17T06:41:02Z
       
  • New insights into the advantages of ammonium as a winemaking nutrient
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Rubén Martínez-Moreno , Manuel Quirós , Pilar Morales , Ramon Gonzalez
      Nitrogen limitation is the most common cause for stuck or sluggish fermentation in winemaking, and it is usually dealt with by supplementing grape juice with either ammonium salts or organic nutrients. These practices have a direct impact on both fermentation kinetics and the sensorial features of the final product. The aim of this work is to provide a detailed characterization of yeast physiology in response to ammonium supplementation during alcoholic fermentation. This is done by determining changes in metabolic rates on a high frequency basis, as a sensitive way to detect the impact of fermentation conditions on yeast physiology. Our results indicate that the choice of supplementation strategy has an impact on several enological parameters like fermentation length, volatile acidity, final glycerol content, and aroma profile. Interestingly, a higher proportion of ammonium relates with improved glycerol and volatile acidity, for the same global yeast assimilable nitrogen content. However, ammonium over-supplementation has a negative impact on quality related parameters, notably on volatile acidity and aroma complexity. Production kinetics and final content of several volatile compounds are also differentially influenced by standard or excess ammonium supplementation.


      PubDate: 2014-03-17T06:41:02Z
       
  • Real-time loop-mediated isothermal amplification (LAMP) assay for group
           specific detection of important trichothecene producing Fusarium species
           in wheat
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Carla Denschlag , Johann Rieder , Rudi F. Vogel , Ludwig Niessen
      Trichothecene mycotoxins such as deoxynivaneol (DON), nivalenol (NIV) and T2-Toxin are produced by a variety of Fusarium spp. on cereals in the field and may be ingested by consumption of commodities and products made thereof. The toxins inhibit eukaryotic protein biosynthesis and may thus impair human and animal health. Aimed at rapid and sensitive detection of the most important trichothecene producing Fusarium spp. in a single analysis, a real-time duplex loop-mediated isothermal amplification (LAMP) assay was set up. Two sets of LAMP primers were designed independently to amplify a partial sequence of the tri6 gene in Fusarium (F.) graminearum and of the tri5 gene in Fusarium sporotrichioides, respectively. Each of the two sets detected a limited number of the established trichothecene producing Fusarium-species. However, combination of the two sets in one duplex assay enabled detection of F. graminearum, Fusarium culmorum, Fusarium cerealis, F. sporotrichioides, Fusarium langsethiae and Fusarium poae in a group specific manner. No cross reactions were detected with purified DNA from 127 other fungal species or with cereal DNA. To demonstrate the usefulness of the assay, 100 wheat samples collected from all over the German state of Bavaria were analyzed for the trichothecene mycotoxin DON by HPLC and for the presence of trichothecene producers by the new real-time duplex LAMP assay in parallel analyses. The LAMP assay showed positive results for all samples with a DON concentration exceeding 163ppb. The major advantage of the duplex LAMP assay is that the presence of six of the major trichothecene producing Fusarium spp. can be detected in a rapid and user-friendly manner with only one single assay. To our knowledge this is the first report of the use of a multiplex LAMP assay for fungal organisms.


      PubDate: 2014-03-17T06:41:02Z
       
  • Diversity and activities of yeasts from different parts of a Stilton
           cheese
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Konstantinos Gkatzionis , Dewi Yunita , Robert S.T. Linforth , Matthew Dickinson , Christine E.R. Dodd
      Blue cheeses are very complex food matrices presenting significant spatial differentiation between sections and the Stilton variety also has a hard brown crust making its matrix even more complex. The mycobiota communities in the three sections (blue veins, white core and outer crust) of a Stilton blue cheese were studied by employing culture-independent (TRFLP, DGGE) and culture-dependent analyses. Yeasts isolated from the cheese were studied for aroma production in a dairy model system with and without the starter Lactococcus lactis and filamentous fungus Penicillium roqueforti using SPME GC–MS. Significant qualitative and quantitative differences were observed in the yeast communities between the cheese sections with all the techniques. Yarrowia lipolytica presented strong synergistic activity with P. roqueforti enhancing the production of ketone aroma compounds, characteristic of blue cheeses. Culture techniques allowed the observation of the presence and uneven distribution of two different morphological groups of Debaryomyces hansenii in the different sections and of Trichosporon ovoides but failed to isolate Candida catenulata which dominated some parts of the cheese in the culture-independent analysis. This suggests that this species may be an important early coloniser but fails to survive into the final cheese. The study indicated that the yeast flora in the cheese sections differ including isolates that could affect their aroma profiles.


      PubDate: 2014-03-17T06:41:02Z
       
  • Contributions of σB and PrfA to Listeria monocytogenes salt stress
           under food relevant conditions
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): V.B. Ribeiro , S. Mujahid , R.H. Orsi , T.M. Bergholz , M. Wiedmann , K.J. Boor , M.T. Destro
      Listeria monocytogenes is well known to survive and grow under several stress conditions, including salt stress, which is important for growth in certain foods as well as for host infection. To characterize the contributions, to salt stress response, of transcriptional regulators important for stress response and virulence (i.e., σB and PrfA), we analyzed three L. monocytogenes parent strains and isogenic mutants (ΔsigB, ΔprfA, and ΔsigBΔprfA), representing different serotypes and lineages, for their ability to grow, at 25°C, in BHI with 1.9M NaCl. With regard to growth rate, only the lineage IV strain presented a significant difference between the parent strain and both of its respective mutants lacking prfA (ΔprfA and ΔsigBΔprfA). Conversely, the lineage I and II parent strains showed significantly shorter lag phase in comparison to their respective ΔsigB mutant strains. Intestinal epithelial cell invasion assay and hemolytic activity assays showed a significant role for σB in the former and for PrfA in the latter. To explore the mechanism that may contribute to the extended lag phase in the ΔsigB mutant strain and survival and growth of the parent strain upon salt shock, whole genome transcription profiling was performed to compare transcript levels between the lineage I, serotype 1/2b, parent strain and its isogenic ΔsigB mutant after 30min of lag phase growth at 25°C in the presence of 1.9M NaCl (salt shock) without aeration. Microarray data showed significantly higher transcript levels for 173 genes in the parent strain as compared to the ΔsigB strain. Overall, 102 of the 173 σB up-regulated genes had been identified in previous studies, indicating that 71 genes were newly identified as being up-regulated by σB in this study. We hypothesize that, among these genes newly identified as σB up-regulated, four genes (lmo2174, lmo0530, lmo0527 and lmo0529) may play a major role in response to salt stress. Lmo2174 contains domains that facilitate sensing and producing a transduction signal in the form of cyclic di-GMP, which may activate the enzymes Lmo0527, Lmo0529 and Lmo0530, which encode proteins similar to those responsible for synthesis of exopolysaccharides that may protect the cell by changing the cell wall structure during salt stress. Overall, our data showed that σB, but not PrfA, contributes to growth under salt stress. Moreover, we show that the σB regulon of a L. monocytogenes lineage I strain challenged with salt shock includes salt stress-specific as well as previously unidentified σB up-regulated genes.


      PubDate: 2014-03-17T06:41:02Z
       
  • Quantification of the impact of single and multiple mild stresses on
           outgrowth heterogeneity of Bacillus cereus spores
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): C.C.J. van Melis , H.M.W. den Besten , M.N. Nierop Groot , T. Abee
      Outgrowth heterogeneity of bacterial spore populations complicates both prediction and efficient control of spore outgrowth. In this study, the impact of mild preservation stresses on outgrowth of Bacillus cereus ATCC 14579 spores was quantified during the first stages of outgrowth. Heterogeneity in outgrowth of heat-treated (90°C for 10min) and non-heat-treated germinated single spores to the maximum micro-colony stage of 256 cells was assessed by direct imaging on Anopore strips, placed on BHI plates at pH7 and pH5.5, without and with added NaCl or sorbic acid (HSA). At pH7 non-heated and heat-treated germinated spores required 6h to reach the maximum microcolony stage with limited heterogeneity, and these parameters were only slightly affected with both types of spores when incubated at pH7 with added NaCl. Notably, the most pronounced effects were observed during outgrowth of spores at pH5.5 without and with added NaCl or HSA. Non-heat-treated germinated spores showed again efficient outgrowth with limited heterogeneity reaching the maximum microcolony stage after 6h at pH5.5, which increased to 12h and 16h with added NaCl and HSA, respectively. In contrast, heat-treated spores displayed a strong delay between initial germination and swelling and further outgrowth at pH5.5, resulting in large heterogeneity and low numbers of fastest growers reaching the maximum microcolony stage after 10, 12 and 24h, without and with added NaCl or HSA, respectively. This work shows that Anopore technology provides quantitative information on the impact of combined preservation stresses on outgrowth of single spores, showing that outgrowth of germinated heat-treated spores is significantly affected at pH5.5 with a large fraction of spores arrested in the early outgrowth stage, and with outgrowing cells showing large heterogeneity with only a small fraction committed to relatively fast outgrowth.


      PubDate: 2014-03-12T07:07:29Z
       
  • Response of S. thermophilus LMD-9 to bacitracin: Involvement of a
           BceRS/AB-like module and of the rhamnose–glucose polysaccharide
           synthesis pathway
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): B. Thevenard , C. Besset , S. Choinard , P. Fourcassié , P. Boyaval , V. Monnet , F. Rul
      Streptococcus thermophilus is a lactic acid bacterium of major importance to the dairy industry as it is found in numerous cheeses and is one of the two bacterial species involved in the fermentation of yogurt. Bacterial two-component signal transduction systems (TCSs) play important roles in the process of bacterial environmental adaptation. S. thermophilus LMD-9 possesses eight such TCS systems; however, their functions have thus far been only poorly investigated. Here, we focused on two of the TCSs in LMD-9, TCS06 and TCS07, whose encoding genes are located close to each other on the chromosome, and are associated with those of ABC transporters. TCS06 homologs are frequently found in Lactobacillales, but their function has not yet been determined, while TCS07 and its upstream potential ABC transporter are homologous to the BceRS/AB system, which is involved in bacitracin resistance in Bacillus and Streptococcus species. To investigate the function(s) of TCS06 and TCS07, we constructed and characterized deletion mutants and performed transcriptional analysis in the presence and absence of bacitracin. We show here that both TCS06 and TCS07 regulate the genes in their close vicinity, in particular those encoding ABC transporters. We propose that the response of S. thermophilus to bacitracin includes i) a bacitracin export system, regulated by TCS07 and constituting a BceRS/AB-like detoxification module, and ii) the modification of cell-envelope properties via modulation of rhamnose–glucose polysaccharide synthesis, at least partially regulated by TCS06.


      PubDate: 2014-03-12T07:07:29Z
       
  • Critical environmental and genotypic factors for Fusarium verticillioides
           infection, fungal growth and fumonisin contamination in maize grown in
           northwestern Spain
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Ana Cao , Rogelio Santiago , Antonio J. Ramos , Xosé C. Souto , Olga Aguín , Rosa Ana Malvar , Ana Butrón
      In northwestern Spain, where weather is rainy and mild throughout the year, Fusarium verticillioides is the most prevalent fungus in kernels and a significant risk of fumonisin contamination has been exposed. In this study, detailed information about environmental and maize genotypic factors affecting F. verticillioides infection, fungal growth and fumonisin content in maize kernels was obtained in order to establish control points to reduce fumonisin contamination. Evaluations were conducted in a total of 36 environments and factorial regression analyses were performed to determine the contribution of each factor to variability among environments, genotypes, and genotype×environment interactions for F. verticillioides infection, fungal growth and fumonisin content. Flowering and kernel drying were the most critical periods throughout the growing season for F. verticillioides infection and fumonisin contamination. Around flowering, wetter and cooler conditions limited F. verticillioides infection and growth, and high temperatures increased fumonisin contents. During kernel drying, increased damaged kernels favored fungal growth, and higher ear damage by corn borers and hard rainfall favored fumonisin accumulation. Later planting dates and especially earlier harvest dates reduced the risk of fumonisin contamination, possibly due to reduced incidence of insects and accumulation of rainfall during the kernel drying period. The use of maize varieties resistant to Sitotroga cerealella, with good husk coverage and non-excessive pericarp thickness could also be useful to reduce fumonisin contamination of maize kernels.


      PubDate: 2014-03-12T07:07:29Z
       
  • In vivo application and dynamics of lactic acid bacteria for the
           four-season production of Vastedda-like cheese
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Raimondo Gaglio , Maria Luisa Scatassa , Margherita Cruciata , Viviana Miraglia , Onofrio Corona , Rosalia Di Gerlando , Baldassare Portolano , Giancarlo Moschetti , Luca Settanni
      Twelve lactic acid bacteria (LAB), previously selected in vitro (Gaglio et al., 2014), were evaluated in situ for their potential to act as starter cultures for the continuous four-season production of Vastedda-like cheese, made with raw ewes' milk. The strains belonged to Lactobacillus delbrueckii, Lactococcus lactis subsp. cremoris, Leuconostoc mesenteroides subsp. mesenteroides and Streptococcus thermophilus. LAB were first inoculated in multiple-strain combinations on the basis of their optimal growth temperatures in three process conditions which differed for milk treatment and medium for strain development: process 1, growth of strains in the optimal synthetic media and pasteurised milk; process 2, growth of strains in whey based medium (WBM) and pasteurised milk; and process 3, growth of strains in WBM and raw milk. The strains that acidified the curds in short time, as shown by a pH drop, were all mesophilic and were then tested in a single inoculum through process 3. Randomly amplified polymorphic DNA (RAPD)-PCR analysis applied to the colonies isolated from the highest dilutions of samples confirmed the dominance of the added strains after curd acidification, stretching and storage. After 15days of refrigerated storage, the decrease in pH values showed an activity of the mesophilic strains at low temperatures, but only Lc. lactis subsp. cremoris PON153, Ln. mesenteroides subsp. mesenteroides PON259 and PON559 increased their number during the 15days at 7°C. A sensory evaluation indicated that the cheeses obtained by applying protocol 3 and by inoculation with lactococci are the most similar to the protected denomination of origin (PDO) cheese and received the best scores by the judges. Thus, the experimental cheeses obtained with raw milk and inoculated with single and multiple combinations of lactococci were subjected to the analysis of the volatile organic compounds (VOCs) carried out by a headspace solid phase microextraction (SPME) technique coupled with gas chromatography with mass spectrometric detection (GC/MS). The dominance of lactococci over thermophilic LAB of raw milk was verified during summer production and, based on the combination of VOC profiles and sensory evaluation of the final cheeses, the multi-strain Lactococcus culture resulted in the most suitable starter preparation for the full-year production of Vastedda-like cheese.


      PubDate: 2014-03-07T07:18:18Z
       
  • Validation according to ISO 16140:2003 of a commercial real-time PCR-based
           method for detecting Campylobacter jejuni, C. coli, and C. lari in foods
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): W. Vencia , C. Nogarol , D.M. Bianchi , S. Gallina , F. Zuccon , D. Adriano , M. Gramaglia , L. Decastelli
      Campylobacteriosis was the most frequently reported zoonosis in the European Union (EU) in 2010, with Campylobacter jejuni, Campylobacter coli, and Campylobacter lari as the most frequently reported species in foodborne outbreaks (FBOs). Relatively sensitive to environmental factors, these species may be present in low numbers. In line with EU policy for food control and FBO detection and in view of the need to reduce response time, we validated an alternative molecular method according to ISO 16140:2003 which establishes the general principle and technical protocol for the validation of alternative methods in the microbiological analysis of food. We used a qualitative real-time PCR commercial kit for the detection of C. jejuni, C. coli, and C. lari in two food categories “fruit and vegetable-based products” and “dairy products”. The validation protocol comprises two phases: the first is a method comparison study of the alternative method against the reference method, and the second is an interlaboratory study of each of the two methods. In the first step, ISO 16140:2003 validation examines the following parameters: limit of detection (LOD); relative accuracy, relative specificity and sensitivity; relative detection level (RDL); and inclusivity and exclusivity. Except for LOD, inclusivity and exclusivity, the other steps were performed against the reference method (ISO 10272:2006). The LOD of the real-time PCR method was set at 4CFU/25g or mL for both food categories. Relative accuracy (98.33%), specificity (96.77%), and sensitivity (100%) were recorded for the food category “fruit and vegetable-based products” and 93.3%, 88.24%, 100%, respectively, for “dairy products”. The RDL according to Fisher's exact test was p =1 for both food categories, for each level, and each food/strain combination. The interlaboratory study results showed correct identification of all 24 blind samples with both methods by all the participating laboratories. The results show that this commercial kit is suitable for the rapid detection of C. jejuni, C. coli, and C. lari on fruit, vegetables and dairy products and may aid in official controls. In conclusion, the use of alternative methods is recommended for the rapid identification of positive samples and the identification of the possible bacterial source in a FBO within 48h.


      PubDate: 2014-03-07T07:18:18Z
       
  • Detection, enumeration and characterization of Yersinia enterocolitica
           4/O:3 in pig tonsils at slaughter in Northern Italy
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Silvia Bonardi , Irene Alpigiani , Stefano Pongolini , Marina Morganti , Silvia Tagliabue , Cristina Bacci , Franco Brindani
      Tonsils from 150 pigs slaughtered at 270days or older were tested for Yersinia enterocolitica with different cultural methods. Samples were collected in three different abattoirs of Northern Italy between April and November 2012 and were analysed by direct plating on cefsulodin–irgasan–novobiocin (CIN) agar and by enrichment procedures following the ISO 10273:2003 reference method. Twenty-three (15.3%) samples were positive: 22 tonsils (14.7%) were positive for human pathogenic Y. enterocolitica bio-serotype 4/O:3 and one tonsil (0.7%) for Y. enterocolitica bio-serotype 1A/7,8-8,8,19. Seventeen samples out of 23 (73.9%) were positive by direct plating method. Among the enrichment procedures, the best recovery rate (8 positives out of 23; 34.8%) was obtained by the two-day enrichment in peptone–sorbitol–bile (PSB) broth followed by plating on CIN agar plates. The two-day enrichment in PSB followed by potassium hydroxide (KOH) treatment before plating onto CIN agar gave 7 positives out of 23 (30.4%), decreasing to 3 positives (13.0%) without KOH treatment. The worst results were obtained by prolonged (five days) enrichment in PSB, with or without KOH treatment, followed by plating on CIN agar: 4.3% (1 out of 23) and 0.0% recovery rates, respectively. The mean concentration was 1.9×104 CFU/g, with a minimum of 1.0×102 CFU/g and a maximum of 5.8×104 CFU/g, thus demonstrating that tonsils may play an important role in contamination of pluck sets, carcasses, and slaughterhouse environment. Prevalence of virulence genes among the Y. enterocolitica 4/O:3 isolates was as follows: 12/22 (54.5%) for yadA, 21/22 (95.5%) for ail, 21/22 (95.5%) for inv and 22/22 (100%) for ystA. All Y. enterocolitica 4/O:3 isolates were sensitive to amoxicillin/clavulanic acid, ciprofloxacin and ceftazidime and resistant to ampicillin and cephalotin. High proportions of 4/O:3 isolates (95%) were sensitive to cefotaxime, gentamicin, kanamicin and nalidixic acid. High levels of resistance were observed to sulphonamide compounds (91%), streptomycin (64%) and chloramphenicol (55%). Multi-resistant isolates were very common; resistance to three or more antimicrobials was observed in 91% (20/22) of 4/O:3 isolates. High level of resistance to chloramphenicol was possibly due to coresistance to tiamphenicol, which was detected in 100% of the isolates. XbaI-PFGE detected four clusters among the 22 Y. enterocolitica 4/O:3 isolates. The most represented accounted for 77% (17/22) of the isolates, the second most common was found in 14% (3/22) of the isolates and the two other profiles were observed in single isolates. The comparison with a selection of human isolates supported the role of the pig as reservoir of 4/O:3 Y. enterocolitica.


      PubDate: 2014-03-07T07:18:18Z
       
  • Leuconostoc bacteriophages from blue cheese manufacture: long-term
           survival, resistance to thermal treatments, high pressure homogenization
           and chemical biocides of industrial application
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Silvina A. Pujato , Daniela M. Guglielmotti , Hans-W. Ackermann , Francesca Patrignani , Rosalba Lanciotti , Jorge A. Reinheimer , Andrea Quiberoni
      Nine Leuconostoc mesenteroides phages were isolated during blue cheese manufacture yielding faulty products with reduced eye formation. Their morphologies, restriction profiles, host ranges and long-term survival rates (25°C, 8°C, −20°C and −80°C) were analysed. Based on restriction analysis, six of them were further examined regarding resistance to physical (heat and high pressure homogenization, HPH) and chemical treatments (ethanol, sodium hypochlorite, peracetic acid, biocides A, C, E and F). According to their morphology, L. mesenteroides phages studied in the present work belonged to the Caudovirales order and Siphoviridae family. Six distinct restriction patterns were obtained with EcoRV, HindIII, ClaI and XhoI enzymes, revealing interesting phage diversity in the dairy environment. No significant reductions in phage counts were observed after ten months of storage at –20°C and −80°C, while slightly and moderate decrease in phage numbers were noticed at 8°C and 25°C, respectively. The phages subjected to heat treatments generally showed high resistance at 63°C and moderate resistance at 72°C. However, 80°C for 30min and 90°C for 2min led to complete inactivation of viral particles. In general, the best ethanol concentration tested was 75%, as complete inactivation for most Leuconostoc phages within 30min of incubation was achieved. Peracetic acid, and biocides A, C, E and F were highly effective when used at the same or at a moderately lower concentration as recommended by the producer. Usually, moderate or high concentrations (600–1600ppm) of sodium hypochlorite were necessary to completely inactivate phage particles. Leuconostoc phages were partially inactivated by HPH treatments as remaining viral particles were found even after 8 passes at 100MPa. This is the first report of L. mesenteroides phages isolated from an Argentinean dairy cheese plant. The results of this work could be useful for establishing the most effective physical and chemical treatments for inactivating phages in industrial plants and laboratory environments.


      PubDate: 2014-03-07T07:18:18Z
       
  • Enterobacteriaceae resistant to third-generation cephalosporins and
           quinolones in fresh culinary herbs imported from Southeast Asia
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Kees Veldman , Arie Kant , Cindy Dierikx , Alieda van Essen-Zandbergen , Ben Wit , Dik Mevius
      Since multidrug resistant bacteria are frequently reported from Southeast Asia, our study focused on the occurrence of ESBL-producing Enterobacteriaceae in fresh imported herbs from Thailand, Vietnam and Malaysia. Samples were collected from fresh culinary herbs imported from Southeast Asia in which ESBL-suspected isolates were obtained by selective culturing. Analysis included identification by MALDI-TOF mass spectrometry, susceptibility testing, XbaI-PFGE, microarray, PCR and sequencing of specific ESBL genes, PCR based replicon typing (PBRT) of plasmids and Southern blot hybridization. In addition, the quinolone resistance genotype was characterized by screening for plasmid mediated quinolone resistance (PMQR) genes and mutations in the quinolone resistance determining region (QRDR) of gyrA and parC. The study encompassed fifty samples of ten batches of culinary herbs (5 samples per batch) comprising nine different herb variants. The herbs originated from Thailand (Water morning glory, Acacia and Betel leaf), Vietnam (Parsley, Asian pennywort, Houttuynia leaf and Mint) and Malaysia (Holy basil and Parsley). By selective culturing 21 cefotaxime resistant Enterobacteriaceae were retrieved. Array analysis revealed 18 isolates with ESBL genes and one isolate with solely non-ESBL beta-lactamase genes. Mutations in the ampC promoter region were determined in two isolates with PCR and sequencing. The isolates were identified as Klebsiella pneumoniae (n=9), Escherichia coli (n=6), Enterobacter cloacae complex (n=5) and Enterobacter spp. (n=1). All isolates tested were multidrug resistant. Variants of CTX-M enzymes were predominantly found followed by SHV enzymes. PMQR genes (including aac(6′)-1b-cr, qnrB and qnrS) were also frequently detected. In almost all cases ESBL and quinolone resistance genes were located on the same plasmid. Imported fresh culinary herbs from Southeast Asia are a potential source for contamination of food with multidrug resistant bacteria. Because these herbs are consumed without appropriate heating, transfer to human bacteria cannot be excluded.


      PubDate: 2014-03-07T07:18:18Z
       
  • Influence of different proteolytic strains of Streptococcus thermophilus
           in co-culture with Lactobacillus delbrueckii subsp. bulgaricus on the
           metabolite profile of set-yoghurt
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Sarn Settachaimongkon , M.J. Robert Nout , Elsa C. Antunes Fernandes , Kasper A. Hettinga , Jacques M. Vervoort , Toon C.M. van Hooijdonk , Marcel H. Zwietering , Eddy J. Smid , Hein J.F. van Valenberg
      Proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus is one of the key factors that determine the fermentation process and final quality of yoghurt. In this study, the interaction between different proteolytic strains of S. thermophilus and L. delbrueckii subsp. bulgaricus was investigated in terms of microbial growth, acidification and changes in the biochemical composition of milk during set-yoghurt fermentation. A complementary metabolomics approach was applied for global characterization of volatile and non-volatile polar metabolite profiles of yoghurt associated with proteolytic activity of the individual strains in the starter cultures. The results demonstrated that only non-proteolytic S. thermophilus (Prt−) strain performed proto-cooperation with L. delbrueckii subsp. bulgaricus. The proto-cooperation resulted in significant higher populations of the two species, faster milk acidification, significant abundance of aroma volatiles and non-volatile metabolites desirable for a good organoleptic quality of yoghurt. Headspace SPME-GC/MS and 1H NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Furthermore, multivariate statistical analysis allows discriminating set-yoghurts fermented by different types of starter cultures according to their metabolite profiles. Our finding underlines that selection of suitable strain combinations in yoghurt starters is important for achieving the best technological performance regarding the quality of product.


      PubDate: 2014-03-07T07:18:18Z
       
  • Shiga toxin and beta-lactamases genes in Escherichia coli phylotypes
           isolated from carcasses of broiler chickens slaughtered in Iran
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Mahboube Bagheri , Reza Ghanbarpour , Hesam Alizade
      Two hundred and four Escherichia coli strains were isolated from external and visceral cavity surfaces of 102 slaughtered broiler carcasses. The isolates were screened to determine the phylogenetic background and presence of Shiga toxins (stx1 , stx2 ), intimin (eae) and beta-lactamase (bla TEM, blaSHV ) genes. Phylotyping results revealed that the E. coli isolates segregated in four phylogenetic groups A (56.86%), B1 (19.12%), B2 (4.90%) and D (19.12%). PCR assays revealed that 13 isolates (6.37%) from 12 carcasses were positive for eae (12 isolates) and/or stx2 (2) genes. The eae positive isolates belonged to phylogenetic groups A (A0, A1), B1, B2 (B22) and D (D2). Two stx2 positive and seven eae positive isolates were recovered from visceral cavity surface, whereas only 5 eae positive isolates were from the external surface of the carcasses. On the other hand, thirty one E. coli strains isolated from visceral cavity and external surface of 26 carcasses carried the blaTEM (27) and blaSHV (4) genes and belonged to different phylo-groups. This study suggests that broiler carcasses could be considered as an important source of EPEC and STEC pathotypes in southeast of Iran; as well as the examined antibiotic resistance genes, which were carried by some isolates and could be transferred to pathogens through the food chain.


      PubDate: 2014-03-07T07:18:18Z
       
  • Influence of the farming system on the epiphytic yeasts and yeast-like
           fungi colonizing grape berries during the ripening process
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Guilherme Martins , Jessica Vallance , Anne Mercier , Warren Albertin , Panagiotis Stamatopoulos , Patrice Rey , Aline Lonvaud , Isabelle Masneuf-Pomarède
      Grape berries are colonized by a wide array of epiphytic microorganisms such as yeast and filamentous fungi. This microbiota plays a major role in crop health and also interferes with the winemaking process. In this study, culture-dependent and -independent methods were used to investigate the dynamics and diversity of the yeast and yeast-like microorganisms on the grape berry surface during maturation and the influence of cropping systems in this microflora. The results showed a significant impact of both the farming system and the maturity stage on the epiphytic yeast and yeast-like community. A quantitative approach based on counting cultivable populations indicated an increase in the yeast and yeast-like population during the grape ripening process, reaching a maximum when the berries became overripe. The cultivable yeast and yeast-like population also varied significantly depending on the farming system. Microorganism counts were significantly higher for organically- than conventionally-farmed grapes. The yeast and yeast-like community structures were analysed by culture independent methods, using CE-SSCP. The results revealed changes in the genetic structure of the yeast and yeast-like community throughout the ripening process, as well as the impact of the farming system. Copper-based fungicide treatments were revealed as the main factor responsible for the differences in microbial population densities between samples of different farming systems. The results showed a negative correlation between copper levels and yeast and yeast-like populations, providing evidence that copper inhibited this epiphytic community. Taken together, our results showed that shifts in the microbial community were related to changes in the composition of the grape–berry surface, particularly sugar exudation and the occurrence of copper residues from pesticide treatments.


      PubDate: 2014-03-07T07:18:18Z
       
  • Characterization of Extraintestinal Pathogenic Escherichia coli isolated
           from retail poultry meats from Alberta, Canada
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Mueen Aslam , Mehdi Toufeer , Claudia Narvaez Bravo , Vita Lai , Heidi Rempel , Amee Manges , Moussa Sory Diarra
      Extraintestinal Pathogenic Escherichia coli (ExPEC) have the potential to spread through fecal waste resulting in the contamination of both farm workers and retail poultry meat in the processing plants or environment. The objective of this study was to characterize ExPEC from retail poultry meats purchased from Alberta, Canada and to compare them with 12 human ExPEC representatives from major ExPEC lineages. Fifty-four virulence genes were screened by a set of multiplex PCRs in 700 E. coli from retail poultry meat samples. ExPEC was defined as the detection of at least two of the following virulence genes: papA/papC, sfa, kpsMT II and iutA. Genetic relationships between isolates were determined using pulsed field gel electrophoresis (PFGE). Fifty-nine (8.4%) of the 700 poultry meat isolates were identified as ExPEC and were equally distributed among the phylogenetic groups A, B1, B2 and D. Isolates of phylogenetic group A possessed up to 12 virulence genes compared to 24 and 18 genes in phylogenetic groups B2 and D, respectively. E. coli identified as ExPEC and recovered from poultry harbored as many virulence genes as those of human isolates. In addition to the iutA gene, siderophore-related iroN and fyuA were detected in combination with other virulence genes including those genes encoding for adhesion, protectin and toxin while the fimH, ompT, traT, uidA and vat were commonly detected in poultry ExPEC. The hemF, iss and cvaC genes were found in 40% of poultry ExPEC. All human ExPEC isolates harbored concnf (cytotoxic necrotizing factor 1 altering cytoskeleton and causing necrosis) and hlyD (hemolysin transport) genes which were not found in poultry ExPEC. PFGE analysis showed that a few poultry ExPEC isolates clustered with human ExPEC isolates at 55–70% similarity level. Comparing ExPEC isolated from retail poultry meats provides insight into their virulence potential and suggests that poultry associated ExPEC may be important for retail meat safety. Investigations into the ability of our poultry ExPEC to cause human infections are warranted.


      PubDate: 2014-03-07T07:18:18Z
       
  • Modeling growth of Escherichia coli O157:H7 in fresh-cut lettuce treated
           with neutral electrolyzed water and under modified atmosphere packaging
    • Abstract: Publication date: 2 May 2014
      Source:International Journal of Food Microbiology, Volume 177
      Author(s): Guiomar D. Posada-Izquierdo , Fernando Pérez-Rodríguez , Francisco López-Gálvez , Ana Allende , María I. Gil , Gonzalo Zurera
      The purpose of this study was to evaluate and model the growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to a neutral electrolyzed water (NEW) treatment, packaged in passive modified atmosphere and subsequently stored at different temperatures (4, 8, 13, 16°C) for a maximum of 27days. Results indicated that E. coli O157:H7 was able to grow at 8, 13, and 16°C, and declined at 4°C. However at 8°C, the lag time lasted 19days, above the typical shelf-life time for this type of products. A secondary model predicting growth rate as a function of temperature was developed based on a square-root function. A comparison with literature data indicated that the growth predicted by the model for E. coli O157:H7 was again lower than those observed with other disinfection treatments or packaging conditions (chlorinated water, untreated product, NEW, etc.). The specific models here developed might be applied to predict growth in products treated with NEW and to improve existing quantitative risk assessments.


      PubDate: 2014-03-02T07:10:01Z
       
  • Editorial Board
    • Abstract: Publication date: 17 April 2014
      Source:International Journal of Food Microbiology, Volume 176




      PubDate: 2014-03-02T07:10:01Z
       
  • Influence of moisture content on inactivation of Escherichia coli O157:H7
           and Salmonella enterica serovar Typhimurium in powdered red and black
           pepper spices by radio-frequency heating
    • Abstract: Publication date: 17 April 2014
      Source:International Journal of Food Microbiology, Volume 176
      Author(s): Seul-Gi Jeong , Dong-Hyun Kang
      The influence of moisture content during radio-frequency (RF) heating on heating rate, dielectric properties, and inactivation of foodborne pathogens was investigated. The effect of RF heating on the quality of powdered red and black pepper spices with different moisture ranges was also investigated. Red pepper (12.6%, 15.2%, 19.1%, and 23.3% dry basis, db) and black pepper (10.1%, 17.2%, 23.7%, and 30.5% db) inoculated with Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium were treated in a RF heating system with 27.12MHz. The heating rate of the sample was dependent on moisture content up to 19.1% (db) of red pepper and 17.2% (db) of black pepper, but there was a significant decrease in the heating rate when the moisture content was increased beyond these levels. The dielectric properties of both samples increased with a rise in moisture content. As the moisture content increased, treatment time required to reduce E. coli O157:H7 and S. Typhimurium by more than 7logCFU/g (below the detection limit, 1logCFU/g) decreased and then increased again without affecting product quality when the moisture content exceeded a level corresponding to the peak heating rate. RF treatment significantly (P <0.05) reduced moisture content of both spices. These results suggest that RF heating can be effectively used to not only control pathogens but also reduce moisture levels in spices and that the effect of inactivation is dependent on moisture content.


      PubDate: 2014-02-20T07:06:03Z
       
  • Method for HEV detection in raw pig liver products and its implementation
           for naturally contaminated food
    • Abstract: Publication date: 17 April 2014
      Source:International Journal of Food Microbiology, Volume 176
      Author(s): Sandra Martin-Latil , Catherine Hennechart-Collette , Laurent Guillier , Sylvie Perelle
      It is now recognized that Hepatitis E virus (HEV) infection is not confined to developing countries. HEV infection is a growing public health concern in industrialized countries where the disease is mainly autochthonous, caused by HEV genotypes 3 and 4 and is today considered to be zoonotic. HEV causes acute hepatitis in humans, predominantly through contamination of food and water. Due to the low concentrations found in food and water samples, an efficient and rapid virus concentration method is required for routine control. Because of the absence of a reliable cell culture method for the main enteric viruses most commonly involved in the outbreaks, reverse transcription quantitative real time PCR (RT-qPCR) is now widely used for the detection of RNA viruses in all types of samples. The aim of this study was to provide a rapid and sensitive method for detecting HEV in pig liver products. A method which includes a virus concentration step by PEG has been chosen from 9 protocols to be further validated. We used a one-step duplex RT-qPCR for detecting HEV and the murine norovirus (MNV-1) used as a process control for monitoring the quality of the whole extraction procedure. The mean recovery rates of the HEV and MNV-1 obtained from pig liver sausages were respectively 3.94% and 2.92%, increasing in figatelli to 18.38% and 13.11% respectively. This method also proved to be effective for HEV detection in naturally contaminated foodstuffs containing raw pig liver.


      PubDate: 2014-02-20T07:06:03Z
       
  • Sequence and comparative analysis of Leuconostoc dairy bacteriophages
    • Abstract: Publication date: 17 April 2014
      Source:International Journal of Food Microbiology, Volume 176
      Author(s): Witold Kot , Lars H. Hansen , Horst Neve , Karin Hammer , Susanne Jacobsen , Per D. Pedersen , Søren J. Sørensen , Knut J. Heller , Finn K. Vogensen
      Bacteriophages attacking Leuconostoc species may significantly influence the quality of the final product. There is however limited knowledge of this group of phages in the literature. We have determined the complete genome sequences of nine Leuconostoc bacteriophages virulent to either Leuconostoc mesenteroides or Leuconostoc pseudomesenteroides strains. The phages have dsDNA genomes with sizes ranging from 25.7 to 28.4kb. Comparative genomics analysis helped classify the 9 phages into two classes, which correlates with the host species. High percentage of similarity within the classes on both nucleotide and protein levels was observed. Genome comparison also revealed very high conservation of the overall genomic organization between the classes. The genes were organized in functional modules responsible for replication, packaging, head and tail morphogenesis, cell lysis and regulation and modification, respectively. No lysogeny modules were detected. To our knowledge this report provides the first comparative genomic work done on Leuconostoc dairy phages.


      PubDate: 2014-02-20T07:06:03Z
       
  • Combined steam and ultrasound treatment of broilers at slaughter: A
           promising intervention to significantly reduce numbers of naturally
           occurring campylobacters on carcasses
    • Abstract: Publication date: 17 April 2014
      Source:International Journal of Food Microbiology, Volume 176
      Author(s): Hanieh S. Musavian , Niels H. Krebs , Ulf Nonboe , Janet E.L. Corry , Graham Purnell
      Steam or hot water decontamination treatment of broiler carcasses is hampered by process limitations due to prolonged treatment times and adverse changes to the epidermis. In this study, a combination of steam with ultrasound (SonoSteam®) was investigated on naturally contaminated broilers that were processed at conventional slaughter speeds of 8,500 birds per hour in a Danish broiler plant. Industrial-scale SonoSteam equipment was installed in the evisceration room, before the inside/outside carcass washer. The SonoSteam treatment was evaluated in two separate trials performed on two different dates. Numbers of naturally occurring Campylobacter spp. and TVC were determined from paired samples of skin excised from opposite sides of the breast of the same carcass, before and after treatments. Sampling was performed at two different points on the line: i) before and after the SonoSteam treatment and ii) before the SonoSteam treatment and after 80min of air chilling. A total of 44 carcasses were examined in the two trials. Results from the first trial showed that the mean initial Campylobacter contamination level of 2.35 log10 CFU was significantly reduced (n =12, p <0.001) to 1.40 log10 CFU after treatment. A significant reduction (n =11, p <0.001) was also observed with samples analyzed before SonoSteam treatment (2.64 log10 CFU) and after air chilling (1.44 log10 CFU). In the second trial, significant reductions (n =10, p <0.05) were obtained for carcasses analyzed before (mean level of 2.23 log10 CFU) and after the treatment (mean level of 1.36 log10 CFU). Significant reductions (n =11, p <0.01) were also found for Campylobacter numbers analyzed before the SonoSteam treatment (2.02 log10 CFU) and after the air chilling treatment (1.37 log10 CFU). The effect of air chilling without SonoSteam treatment was determined using 12 carcasses pre- and postchill. Results showed insignificant reductions of 0.09 log10 from a mean initial level of 2.19 log10 CFU. Numbers of TVC before treatments ranged between 3.47 and 4.79 log10 CFU. In all cases, TVC was significantly (p <0.001, n =45 in each trial) reduced by approximately 0.7 log10 CFU. An authorized sensory panel at the Danish Veterinary and Food Administration concluded that broiler carcasses treated with SonoSteam were acceptable for purchase. These conclusions were based on organoleptic differences (smell, skin/meat consistency, texture and color) of treated vs. untreated carcasses. Results obtained from this study suggest that steam–ultrasound treatment of carcasses at broiler processing plants can significantly reduce numbers of Campylobacter on naturally contaminated broilers.


      PubDate: 2014-02-20T07:06:03Z
       
 
 
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