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  Subjects -> BIOLOGY (Total: 2603 journals)
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MICROBIOLOGY (210 journals)                  1 2 3     

Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 6)
Addiction Genetics     Open Access   (Followers: 3)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 14)
Advances in Microbiology     Open Access   (Followers: 15)
Advances in Molecular Imaging     Open Access   (Followers: 3)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Microbiology Research     Open Access   (Followers: 1)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 13)
American Journal of Microbiological Research     Open Access  
American Journal of Microbiology     Open Access   (Followers: 14)
American Journal of Molecular Biology     Open Access   (Followers: 3)
American Journal of Stem Cell Research     Open Access   (Followers: 1)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 5)
Annals of Microbiology     Hybrid Journal   (Followers: 7)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 21)
Antimicrobial Agents and Chemotherapy     Full-text available via subscription   (Followers: 15)
Applied and Environmental Microbiology     Full-text available via subscription   (Followers: 24)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 7)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 23)
Archives of Microbiology     Hybrid Journal   (Followers: 3)
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
Bio-Research     Full-text available via subscription  
BioArchitecture     Full-text available via subscription  
Biocell     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Research     Open Access   (Followers: 3)
BioMolecular Concepts     Full-text available via subscription   (Followers: 2)
Biomolecules     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 6)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases & Medical Microbiology     Hybrid Journal   (Followers: 1)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 3)
Cell Biology : Research & Therapy     Partially Free  
Cell Host & Microbe     Full-text available via subscription   (Followers: 7)
Cell Medicine     Open Access  
Cell Regeneration     Open Access  
Cell Stem Cell     Full-text available via subscription   (Followers: 19)
Cells     Open Access   (Followers: 1)
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 8)
Cellular Microbiology     Hybrid Journal   (Followers: 4)
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (Followers: 2)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (Followers: 13)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 3)
Clinical Microbiology Reviews     Full-text available via subscription   (Followers: 10)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 8)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Continental Journal of Microbiology     Open Access   (Followers: 3)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 6)
Current Issues in Molecular Biology     Open Access  
Current Microbiology     Hybrid Journal   (Followers: 5)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 15)
Current Tissue Engineering     Hybrid Journal   (Followers: 1)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 4)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 3)
Disease and Molecular Medicine     Open Access   (Followers: 1)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (Followers: 2)
Environmental Microbiology     Hybrid Journal   (Followers: 7)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 3)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 5)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 3)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 10)
European Journal of Microbiology and Immunology     Open Access   (Followers: 6)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 1)
Fems Immunology & Medical Microbiology     Hybrid Journal   (Followers: 6)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 6)
Fems Microbiology Letters     Hybrid Journal   (Followers: 13)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 16)
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 11)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 1)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 2)
Frontiers in Cellular Neuroscience     Open Access  
Frontiers in Microbiology     Open Access   (Followers: 5)
Frontiers in Molecular Neuroscience     Open Access  
Future Microbiology     Full-text available via subscription   (Followers: 2)
Future Virology     Full-text available via subscription   (Followers: 3)
Gene Expression     Full-text available via subscription  
Genetica si Biologie Moleculara     Open Access   (Followers: 1)
Genetics and Molecular Research     Open Access   (Followers: 3)
Geomicrobiology Journal     Hybrid Journal   (Followers: 1)
Gut Microbes     Full-text available via subscription   (Followers: 2)
Indian Journal of Microbiology     Hybrid Journal   (Followers: 1)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 6)
International Arabic Journal of Antimicrobial Agents     Open Access   (Followers: 4)
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 2)
International Journal of Bacteriology     Open Access  
International Journal of Bioassays     Open Access   (Followers: 5)
International Journal of Biotechnology and Molecular Biology Research     Open Access  
International Journal of Food Microbiology     Hybrid Journal   (Followers: 11)
International Journal of Infection and Microbiology     Open Access   (Followers: 1)
International Journal of Medical Microbiology     Hybrid Journal   (Followers: 6)
International Journal of Systematic and Evolutionary Microbiology     Full-text available via subscription   (Followers: 2)
International Microbiology     Open Access   (Followers: 2)
Invertebrate Immunity     Open Access  

        1 2 3     

Journal Cover International Journal of Food Microbiology
   Journal TOC RSS feeds Export to Zotero [13 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0168-1605
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.386]   [H-I: 108]
  • Mupirocin-mucin agar for selective enumeration of Bifidobacterium bifidum
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): Radko Pechar , Vojtech Rada , Lucia Parafati , Sarka Musilova , Vera Bunesova , Eva Vlkova , Jiri Killer , Jakub Mrazek , Vladimir Kmet , Roman Svejstil
      Bifidobacterium bifidum is a bacterial species exclusively found in the human intestinal tract. This species is becoming increasingly popular as a probiotic organism added to lyophilized products. In this study, porcine mucin was used as the sole carbon source for the selective enumeration of B. bifidum in probiotic food additives. Thirty-six bifidobacterial strains were cultivated in broth with mucin. Only 13 strains of B. bifidum utilized the mucin to produce acids. B. bifidum was selectively enumerated in eight probiotic food supplements using agar (MM agar) containing mupirocin (100mg/L) and mucin (20g/L) as the sole carbon source. MM agar was fully selective if the B. bifidum species was presented together with Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, and Bifidobacterium longum subsp. longum species and with lactic acid bacteria (lactobacilli, streptococci). Isolated strains of B. bifidum were identified using biochemical, PCR, MALDI-TOF procedures and 16S rRNA gene sequencing. The novel selective medium was also suitable for the isolation of B. bifidum strains from human fecal samples.


      PubDate: 2014-09-16T19:21:42Z
       
  • Editorial Board
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190




      PubDate: 2014-09-16T19:21:42Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190




      PubDate: 2014-09-16T19:21:42Z
       
  • Control of Listeria monocytogenes in fresh cheese using protective lactic
           acid bacteria
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): M.C. Coelho , C.C.G. Silva , S.C. Ribeiro , M.L.N.E. Dapkevicius , H.J.D. Rosa
      In the past years, there has been a particular focus on the application of bacteriocins produced by lactic acid bacteria (LAB) in controlling the growth of pathogenic bacteria in foods. The aim of this study was to select LAB strains with antimicrobial activity, previously isolated from a traditional Azorean artisanal cheese (Pico cheese), in order to identify those with the greatest potential in reducing Listeria monocytogenes in fresh cheese. Eight bacteriocin producer strains identified as Lactococcus lactis (1) and Enterococcus faecalis (7) were tested. In general, the bacteriocin-producing strains presented a moderate growth in fresh cheese at refrigeration temperatures (4°C), increasing one log count in three days. They exhibited slow acidification capacity, despite the increased production of lactic acid displayed by some strains after 24h. Bacteriocin activity was only detected in the whey of fresh cheese inoculated with two Enterococcus strains, but all cheeses made with bacteriocin-producing strains inhibited L. monocytogenes growth in the agar diffusion bioassay. No significant differences were found in overall sensory evaluation made by a non-trained panel of 50–52 tasters using the isolates as adjunct culture in fresh cheese, with the exception of one Enterococcus strain. To test the effect of in situ bacteriocin production against L. monocytogenes, fresh cheese was made from pasteurized cows' milk inoculated with bacteriocin-producing LAB and artificially contaminated with approximately 106 CFU/mL of L. monocytogenes. The numbers of L. monocytogenes were monitored during storage of fresh cheese at refrigeration temperature (4°C) for up to 15days. All strains controlled the growth of L. monocytogenes, although some Enterococcus were more effective in reducing the pathogen counts. After 7days, this reduction was of approximately 4 log units compared to the positive control. In comparison, an increase of 4logCFU/mL in pathogen numbers was detected over the same period, in the absence of bacteriocin-producing LAB. The combination of two bacteriocin producing Enterococcus sp. optimized the reduction of L. monocytogenes counts in fresh cheese, reducing by approximately 5logunits after 7days. The present work demonstrates that using bacteriocin-producing strains in the manufacture of fresh cheese might contribute to preventing the growth of undesirable pathogenic bacteria such as L. monocytogenes. A blend of two strains demonstrated great potential as a protective culture for the cheese making process.


      PubDate: 2014-09-16T19:21:42Z
       
  • Genetic diversity of FLO1 and FLO5 genes in wine flocculent Saccharomyces
           cerevisiae strains
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): Rosanna Tofalo , Giorgia Perpetuini , Paola Di Gianvito , Maria Schirone , Aldo Corsetti , Giovanna Suzzi
      Twenty-eight flocculent wine strains were tested for adhesion and flocculation phenotypic variability. Moreover, the expression patterns of the main genes involved in flocculation (FLO1, FLO5 and FLO8) were studied both in synthetic medium and in presence of ethanol stress. Molecular identification and typing were achieved by PCR-RFLP of the 5.8S ITS rRNA region and microsatellite PCR fingerprinting, respectively. All isolates belong to Saccharomyces cerevisiae species. The analysis of microsatellites highlighted the intraspecific genetic diversity of flocculent wine S. cerevisiae strains allowing obtaining strain-specific profiles. Moreover, strains were characterized on the basis of adhesive properties. A wide biodiversity was observed even if none of the tested strains were able to form biofilms (or ‘mats’), or to adhere to polystyrene. Moreover, genetic diversity of FLO1 and FLO5 flocculating genes was determined by PCR. Genetic diversity was detected for both genes, but a relationship with the flocculation degree was not found. So, the expression patterns of FLO1, FLO5 and FLO8 genes was investigated in a synthetic medium and a relationship between the expression of FLO5 gene and the flocculation capacity was established. To study the expression of FLO1, FLO5 and FLO8 genes in floc formation and ethanol stress resistance qRT-PCR was carried out and also in this case strains with flocculent capacity showed higher levels of FLO5 gene expression. This study confirmed the diversity of flocculation phenotype and genotype in wine yeasts. Moreover, the importance of FLO5 gene in development of high flocculent characteristic of wine yeasts was highlighted. The obtained collection of S. cerevisiae flocculent wine strains could be useful to study the relationship between the genetic variation and flocculation phenotype in wine yeasts.


      PubDate: 2014-09-16T19:21:42Z
       
  • Exploring the diversity of extremely halophilic archaea in food-grade
           salts
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): Olivier Henriet , Jeanne Fourmentin , Bruno Delincé , Jacques Mahillon
      Salting is one of the oldest means of food preservation: adding salt decreases water activity and inhibits microbial development. However, salt is also a source of living bacteria and archaea. The occurrence and diversity of viable archaea in this extreme environment were assessed in 26 food-grade salts from worldwide origin by cultivation on four culture media. Additionally, metagenomic analysis of 16S rRNA gene was performed on nine salts. Viable archaea were observed in 14 salts and colony counts reached more than 105 CFU per gram in three salts. All archaeal isolates identified by 16S rRNA gene sequencing belonged to the Halobacteriaceae family and were related to 17 distinct genera among which Haloarcula, Halobacterium and Halorubrum were the most represented. High-throughput sequencing generated extremely different profiles for each salt. Four of them contained a single major genus (Halorubrum, Halonotius or Haloarcula) while the others had three or more genera of similar occurrence. The number of distinct genera per salt ranged from 21 to 27. Halorubrum had a significant contribution to the archaeal diversity in seven salts; this correlates with its frequent occurrence in crystallization ponds. On the contrary, Haloquadratum walsbyi, the halophilic archaea most commonly found in solar salterns, was a minor actor of the food-grade salt diversity. Our results indicate that the occurrence and diversity of viable halophilic archaea in salt can be important, while their fate in the gastrointestinal tract after ingestion remains largely unknown.


      PubDate: 2014-09-16T19:21:42Z
       
  • Membrane lipid composition and stress/virulence related gene expression of
           Salmonella Enteritidis cells adapted to lactic acid and trisodium
           phosphate and their resistance to lethal heat and acid stress
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): Yishan Yang , Mellissa Irlianti Kadim , Wei Jie Khoo , Qianwang Zheng , Magdiel Inggrid Setyawati , Yu-Jin Shin , Seung-Cheol Lee , Hyun-Gyun Yuk
      This study evaluated the acid and heat resistance of Salmonella Enteritidis in simulated gastric fluid (pH2.0) and during thermal treatment (54–60°C), respectively, after adaptation to lactic acid (LA) or trisodium phosphate (TSP) at various pHs (pH5.3–9.0). The changes in membrane lipid composition and expression levels of RpoS and RpoH were examined to elucidate their roles in bacterial stress resistance. Transcriptional profile of several virulence-related genes was also analyzed. Results showed that LA-adapted cells at pH5.3 and 6.3 had higher acid and heat resistance than control cells and cells adapted to TSP at pH8.3 and 9.0. LA-adapted cells had the lowest ratio of unsaturated to saturated fatty acids, indicating that they might possess a less fluid membrane. It was observed that the expression levels of RpoH and RpoS were upregulated in TSP-adapted cells but not in LA-adapted cells. Thus, these results indicate that the increased acid and heat resistance of LA-adapted S. Enteritidis was possibly due to the decreased membrane fluidity instead of the upregulation of RpoS and RpoH. About 6.0, 2.1, and 2.46-fold upregulation of spvR, avrA, and hilA were observed in cells adapted to TSP at pH9.0, except sefA that had its highest expression level in the control cells, indicating that the expression of these virulence genes highly depends on environmental conditions. This is the first study to show that the alteration in the cytoplasmic membrane rather than RpoS and RpoH plays a more crucial role in conferring greater acid and heat resistance on LA-adapted S. Enteritidis, thus providing a better understanding on the bacterial stress response to acidic conditions.


      PubDate: 2014-09-16T19:21:42Z
       
  • Applicability of a Lactobacillus amylovorus strain as co-culture for
           natural folate bio-enrichment of fermented milk
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): Jonathan Emiliano Laiño , Marianela Juarez del Valle , Graciela Savoy de Giori , Jean Guy Joseph LeBlanc
      The ability of 55 strains from different Lactobacillus species to produce folate was investigated. In order to evaluate folic acid productivity, lactobacilli were cultivated in the folate-free culture medium (FACM). Most of the tested strains needed folate for growth. The production and the extent of vitamin accumulation were distinctive features of individual strains. Lactobacillus amylovorus CRL887 was selected for further studies because of its ability to produce significantly higher concentrations of vitamin (81.2±5.4μg/L). The safety of this newly identified folate producing strain was evaluated through healthy experimental mice. No bacterial translocation was detected in liver and spleen after consumption of CRL887 during 7 days and no undesirable side effects were observed in the animals that received this strain. This strain in co-culture with previously selected folate producing starter cultures (Lactobacillus bulgaricus CRL871, and Streptococcus thermophilus CRL803 and CRL415) yielded a yogurt containing high folate concentrations (263.1±2.4μg/L); a single portion of which would provide 15% of the recommended dietary allowance. This is the first report where a Lactobacillus amylovorus strain was successfully used as co-culture for natural folate bio-enrichment of fermented milk.


      PubDate: 2014-09-16T19:21:42Z
       
  • Combined effects of benomyl and environmental factors on growth and
           expression of the fumonisin biosynthetic genes FUM1 and FUM19 by Fusarium
           verticillioides
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): A. Cruz , P. Marín , N. Magan , M.T. González-Jaén
      Fusarium verticillioides is predominantly responsible of fumonisin contamination of maize and other cereals in Mediterranean climatic regions. This study examined the interaction of the fungicide benomyl, at ED50 and ED90 concentrations (effective doses of benomyl to reduce growth by 50% and 90%, respectively), with a range of temperatures (20–35°C) and water potentials (−0.7, −2.8 and −7.0MPa) compatible with current and foreseen climate change scenarios for these regions on growth and fumonisin biosynthesis in in vitro assays. The expression of fumonisin biosynthetic genes (FUM1 and FUM19) was quantified by real time RT-PCR. FUM1 encodes a polyketide synthase and FUM19 an ABC-type transporter, located both in the fumonisin biosynthetic cluster. The ED50 and ED90 concentrations obtained at 25°C were 0.93mg/L and 3.30mg/L, respectively. Benomyl affected growth and fumonisin gene expression differently but it generally reduced fungal growth and fumonisin biosynthesis and both were significantly affected by temperature and water potential. This indicated that efficacy of benomyl might be compromised at certain conditions, although at similar or lower levels than other fungicides tested. Both fumonisin biosynthetic genes had similar expression patterns in all treatments and their correlation was positive and significant. The results suggested that Mediterranean climatic scenarios might suffer an additional negative impact of climate change by reducing the efficacy of antifungals used to control pathogens and toxigenic fungi.


      PubDate: 2014-09-16T19:21:42Z
       
  • Monitoring of Saccharomyces cerevisiae, Hanseniaspora uvarum, and
           Starmerella bacillaris (synonym Candida zemplinina) populations during
           alcoholic fermentation by fluorescence in situ hybridization
    • Abstract: Publication date: 17 November 2014
      Source:International Journal of Food Microbiology, Volume 191
      Author(s): Chunxiao Wang , Braulio Esteve-Zarzoso , Albert Mas
      Various molecular approaches have been applied as culture-independent techniques to monitor wine fermentations over the last decade. Among them, those based on RNA detection have been widely used for yeast cell detection, assuming that RNA only exists in live cells. Fluorescence in situ hybridization (FISH) targeting intracellular rRNA is considered a promising technique for the investigation of wine ecology. For the present study, we applied the FISH technique in combination with epifluorescence microscopy and flow cytometry to directly quantify populations of Saccharomyces cerevisiae, Hanseniaspora uvarum, and Starmerella bacillaris during alcoholic fermentations. A new specific probe that hybridizes with eight species of Hanseniaspora genus and a second probe specific for Starm. bacillaris were designed, and the conditions for their application to pure cultures, mixed cultures, and wine samples were optimized. Single and mixed fermentations were performed with natural, concentrated must at two different temperatures, 15°C and 25°C. The population dynamics revealed that the Sacch. cerevisiae population increased to 107–108 cells/ml during all fermentations, whereas H. uvarum and Starm. bacillaris tended to increase in single fermentations but remained at levels similar to their inoculations at 106 cells/ml in mixed fermentations. Temperature mainly affected the fermentation duration (slower at the lower temperature) but did not affect the population sizes of the different species. The use of these probes in natural wine fermentations has been validated.


      PubDate: 2014-09-16T19:21:42Z
       
  • Variable flocculation profiles of yeast strains isolated from cachaça
           distilleries
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Florencia Alvarez , Lygia Fátima da Mata Correa , Thalita Macedo Araújo , Bruno Eduardo Fernandes Mota , Luís Eduardo F. Ribeiro da Conceição , Ieso de Miranda Castro , Rogelio Lopes Brandão
      In cachaça production, the use of yeast cells as starters with predictable flocculation behavior facilitates the cell recovery at the end of each fermentation cycle. Therefore, the aim of this work was to explain the behavior of cachaça yeast strains in fermentation vats containing sugarcane through the determination of biochemical and molecular parameters associated with flocculation phenotypes. By analyzing thirteen cachaça yeast strains isolated from different distilleries, our results demonstrated that neither classic biochemical measurements (e.g., percentage of flocculation, EDTA sensitivity, cell surface hydrophobicity, and sugar residues on the cell wall) nor modern molecular approaches, such as polymerase chain reaction (PCR) and real-time PCR (q-PCR), were sufficient to distinctly classify the cachaça yeast strains according to their flocculation behavior. It seems that flocculation is indeed a strain-specific phenomenon that is difficult to explain and/or categorize by the available methodologies.


      PubDate: 2014-09-11T19:18:51Z
       
  • Genetic diversity and dynamics of bacterial and yeast strains associated
           to Spanish-style green table-olive fermentations in large manufacturing
           companies
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Helena Lucena-Padrós , Belén Caballero-Guerrero , Antonio Maldonado-Barragán , José Luis Ruiz-Barba
      We have genotyped a total of 1045 microbial isolates obtained along the fermentation time of Spanish-style green table olives from the fermentation yards (patios) of two large manufacturing companies in the Province of Sevilla, south of Spain. Genotyping was carried out using RAPD-PCR fingerprinting. In general, isolates clustered well into the relevant phylogenetic dendrograms, forming separate groups in accordance to their species adscription. We could identify which bacterial and yeast genotypes (strains) persisted throughout the fermentation at each patio. Also, which of them were more adapted to any of the three stages, i.e. initial, middle and final, described for this food fermentation. A number of genotypes were found to be shared by both patios. Fifty seven of these belonged to five different bacterial species, i.e. Lactobacillus pentosus, Lactobacillus paracollinoides/collinoides, Lactobacillus rapi, Pediococcus ethanolidurans and Staphylococcus sp., although most of them (51) belonged to L. pentosus. Four yeast genotypes were also shared, belonging to the species Candida thaimueangensis, Saccharomyces cerevisiae and Hanseniaspora sp. Two genotypes of L. pentosus were found to be grouped with those of two strains used in commercially available starter cultures, one of them bacteriocinogenic, which were used up to three years before this study in these patios, demonstrating the persistence of selected strains in this environment. Biodiversity was assessed though different indexes, including richness, diversity and dominance. A statistically significant decrease in biodiversity between the initial and final stages of the fermentation was found in both patios. However, values of biodiversity indexes in the fermenters were very similar, and no significant differences were found in the total biodiversity between both patios. This study allowed us to identify a range of well adapted strains (genotypes), especially those belonging to the lactic acid bacteria, which could be useful to improve safety and quality of table olive fermentations.


      PubDate: 2014-09-11T19:18:51Z
       
  • Food safety considerations in relation to Anisakis pegreffii in anchovies
           (Engraulis encrasicolus) and sardines (Sardina pilchardus) fished off the
           Ligurian Coast (Cinque Terre National Park, NW Mediterranean)
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Laura Serracca , Roberta Battistini , Irene Rossini , Annalaura Carducci , Marco Verani , Marino Prearo , Laura Tomei , Gabriella De Montis , Carlo Ercolini
      Engraulis encrasicolus and Sardina pilchardus are pelagic fishes of notable economic and gastronomic importance in the northwest Mediterranean (Ligurian Sea, Italy). The consumption of thermally unprocessed or lightly processed, marinated or salted anchovies and sardines presents a potential risk to acquire anisakiasis, a fish-borne parasitic disease in humans. Prevalence and abundance of Anisakis larvae in Engraulis encrasicolus and Sardina pilchardus from the Monterosso fishing grounds (Cinque Terre National Park, Ligurian Sea, Italy) were assessed, and the larvae were identified by morphological and PCR-RFLP methods. Anisakis larvae, all belonging to Anisakis pegreffii spp. were found in the visceral mass of 1050 anchovies (0.8% overall prevalence), whereas no Anisakis larvae were found in the 750 sardines examined. According to these data, the risk of acquiring anisakiasis from the consumption of raw or undercooked anchovies and sardines caught in the fishing area we investigated is very low.


      PubDate: 2014-09-11T19:18:51Z
       
  • Microbial succession of grass carp (Ctenopharyngodon idellus) filets
           during storage at 4°C and its contribution to biogenic amines'
           formation
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Hang Wang , Yongkang Luo , Heping Huang , Qian Xu
      Investigation on the microbial succession of grass carp filets during storage at 4°C was carried out. For identification, 16S rRNA genes of the isolated pure strains were sequenced and analyzed. Acinetobacter was dominant in fresh grass carp. Species from the genera Brevundimonas, Empedobacter, Pseudomonas, Microbacterium, Flavobacterium, Moraxella, Shewanella and Soonwooa were also detected at the initial day. The communities were dominated by Aeromonas and Acinetobacter after 6days. Aeromonas followed by Pseudomonas was the predominant genera at the end of shelf-life of grass carp, while other genera such as Shewanella, Acinetobacter, Flavobacteriaceae and Psychrobacter were present in smaller numbers. We investigated biogenic amines' (BAs) production by six strains isolated from spoiled grass carp filets. Shewanella putrefaciens showed significantly higher abilities to produce putrescine, than those from other genera. Aeromonas veronii revealed a strong ability to produce putrescine and cadaverine. However, Pseudomonas and Acinetobacter showed little ability to produce BAs.


      PubDate: 2014-09-11T19:18:51Z
       
  • African fermented foods and probiotics
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Charles M.A.P. Franz , Melanie Huch , Julius Maina Mathara , Hikmate Abriouel , Nabil Benomar , Gregor Reid , Antonio Galvez , Wilhelm H. Holzapfel
      Africa has an age old history of production of traditional fermented foods and is perhaps the continent with the richest variety of lactic acid fermented foods. These foods have a large impact on the nutrition, health and socio-economy of the people of the continent, often plagued by war, drought, famine and disease. Sub-Saharan Africa is the world's region with the highest percentage of chronically malnourished people and high child mortality. Further developing of traditional fermented foods with added probiotic health features would be an important contribution towards reaching the UN Millennium Development Goals of eradication of poverty and hunger, reduction in child mortality rates and improvement of maternal health. Specific probiotic strains with documented health benefits are sparsely available in Africa and not affordable to the majority of the population. Furthermore, they are not used in food fermentations. If such probiotic products could be developed especially for household food preparation, such as cereal or milk foods, it could make a profound impact on the health and well-being of adults and children. Suitable strains need to be chosen and efforts are needed to produce strains to make products which will be available for clinical studies. This can gauge the impact of probiotics on consumers' nutrition and health, and increase the number of people who can benefit.


      PubDate: 2014-09-11T19:18:51Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189




      PubDate: 2014-09-06T19:11:50Z
       
  • Multilocus variable-number of tandem repeat analysis (MLVA) for
           Clostridium tyrobutyricum strains isolated from cheese production
           environment
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Masaharu Nishihara , Hajime Takahashi , Tomoko Sudo , Daisuke Kyoi , Toshio Kawahara , Yoshihiro Ikeuchi , Takashi Fujita , Takashi Kuda , Bon Kimura , Shuichi Yanahira
      Clostridium tyrobutyricum is a gram-positive spore-forming anaerobe that is considered as the main causative agent for late blowing in cheese due to butyric acid fermentation. In this study, multilocus variable-number of tandem repeat (VNTR) analysis (MLVA) for C. tyrobutyricum was developed to identify the source of contamination by C. tyrobutyricum spores in the cheese production environment. For each contig constructed from the results of a whole genome draft sequence of C. tyrobutyricum JCM11008T based on next-generation sequencing, VNTR loci that were effective for typing were searched using the Tandem Repeat Finder program. Five VNTR loci were amplified by polymerase chain reaction (PCR) to determine their number of repeats by sequencing, and MLVA was conducted. 25 strains of C. tyrobutyricum isolated from the environment, raw milk, and silage were classified into 18 MLVA types (DI=0.963). Of the C. tyrobutyricum strains isolated from raw milk, natural cheese, and blown processed cheese, strains with identical MLVA type were detected, which suggested that these strains might have shifted from natural cheese to blown processed cheese. MLVA could be an effective tool for monitoring contamination of natural cheese with C. tyrobutyricum in the processed cheese production environment because of its high discriminability, thereby allowing the analyst to trace the source of contamination.


      PubDate: 2014-09-06T19:11:50Z
       
  • Editorial Board
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189




      PubDate: 2014-09-06T19:11:50Z
       
  • A long term field study of the effect of fungicides penconazole and sulfur
           on yeasts in the vineyard
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Gustavo Cordero-Bueso , Teresa Arroyo , Eva Valero
      This research deals with how two fungicide treatments against powdery mildew, penconazole as a systematic fungicide and sulfur as an inorganic broad-spectrum fungicide, affect the diversity and density of wine yeasts associated with grape berry surfaces and subsequent spontaneous fermentations. Unlike other studies in this area, this work aims to evaluate this effect on the population dynamics in the environment, the conditions of which are not reproducible in the laboratory. A long term (three year) sampling plan was thus devised. A minimum inhibitory concentration assay was also carried out in the laboratory in order to prove the influence of these antifungals on yeast populations. While both antifungal treatments (penconazole and sulfur) were similarly effective against powdery mildew, each had a very different effect on yeast populations. Penconazole showed the most negative effect on biodiversity in the vineyard and was the fungicide to which the isolated yeasts showed the greatest sensitivity. This study therefore evidences the suitability of treatment with sulfur, in both conventional and organic viticulture, to preserve the yeast population associated with grape berries, in particular the Saccharomyces cerevisiae species.


      PubDate: 2014-09-06T19:11:50Z
       
  • Combination of pulsed electric fields, mild heat and essential oils as an
           alternative to the ultrapasteurization of liquid whole egg
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Laura Espina , Silvia Monfort , Ignacio Álvarez , Diego García-Gonzalo , Rafael Pagán
      The production of microbiologically safe liquid whole egg (LWE) by industrial ultrapasteurization is restricted by the high thermal sensitivity of LWE components. This research proposes an alternative treatment based on the application of pulsed electric fields (PEF) and mild heat, in the presence of natural essential oils (EOs) or their individual components (ICs). The obtained results indicate that the successive application of PEF (25kV/ and 100kJ/kg) followed by heat (60°C during 3.5') to LWE added with 200μL/L of lemon EO would reach 4log10 cycles of inactivation of Salmonella Senftenberg 775W and Listeria monocytogenes, when any of these barriers acting alone inactivated less than 1.5log10 cycles of either bacteria. Therefore, the synergism between lemon EO and the successive application of PEF and heat would provide a safety level similar to that of ultrapasteurization treatment for Salmonella Senftenberg 775W and L. monocytogenes, but at a lower temperature. To a lesser extent, synergism with the successive application of PEF and heat was also observed in the presence of 200μL/L of carvacrol, citral, (+)-limonene, or mandarin EO, reaching about 3.5log10 cycles of inactivation in Salmonella Senftenberg and 3.0log10 cycles in L. monocytogenes, respectively. A sensory test on LWE containing 200μL/L of each additive in the form of omelets and sponge cakes revealed that this concentration of mandarin EO, lemon EO, or (+)-limonene did not decrease the sensory acceptability of the LWE-containing products, and lemon EO and mandarin EO even increased the hedonic acceptability of sponge cakes. In conclusion, this process could be applied in the food industry to obtain microbiologically safe LWE, which could be used to produce egg-based products without decreasing (and even increasing) their sensory appeal.


      PubDate: 2014-09-01T18:44:46Z
       
  • Reduction of an E. coli O157:H7 and Salmonella composite on fresh
           strawberries by varying antimicrobial washes and vacuum perfusion
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Joshua B. Gurtler , Rebecca B. Bailey , Tony Z. Jin , Xuetong Fan
      A 2011 outbreak of hemorrhagic colitis, which resulted in the death of two individuals, was associated with contaminated strawberries. A study was conducted to identify antimicrobial washes effective at reducing E. coli O157:H7 and Salmonella enterica from the surface of fresh whole strawberries during two-minute immersion washes. Twenty-seven antimicrobial treatments were tested. Vacuum perfusion was applied to strawberries during chlorine and peracetic acid treatments to promote infiltration of sanitizer into porous strawberry tissue. Strawberries were inoculated to 7.1logCFU/strawberry with a seven-strain bacterial composite, consisting of three strains of E. coli O157:H7 and four serovars of Salmonella enterica. Berries were air-dried for 2h and immersed in circulating antimicrobial solutions for 120s at 22°C. Four treatments reduced ≥3.0logCFU/strawberry, including (a) 1% acetic acid+1% H2O2, (b) 30% ethanol+1% H2O2, (c) 90ppm peracetic acid, and (d) 1% lactic acid+1% H2O2. Two additional treatments that reduced 2.8logCFU/strawberry were (a) 40% ethanol, and (b) 1% each of phosphoric+fumaric acids. Eight treatments reduced 2.0–2.6logCFU/strawberry. Five treatments reduced <1.45CFU/strawberry, including (a) 1% citric acid, (b) 1% lactic acid, (c) 1% acetic acid, (d) 0.5% each of acetic+citric acids and (e) 0.5% each of acetic+lactic acids. The use of vacuum perfusion with 200ppm chlorine or 90ppm peracetic acid did not reduce greater populations of pathogens than did the same treatments without vacuum perfusion. Fourteen treatments reduced no more pathogens (p<0.05) than did sterile deionized water. Results from this study provide some options for end-point decontamination of strawberries for retail operations just prior to serving to customers.


      PubDate: 2014-09-01T18:44:46Z
       
  • The influence of subminimal inhibitory concentrations of benzalkonium
           chloride on biofilm formation by Listeria monocytogenes
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Sagrario Ortiz , Victoria López , Joaquín V. Martínez-Suárez
      Disinfectants, such as benzalkonium chloride (BAC), are commonly used to control Listeria monocytogenes and other pathogens in food processing plants. Prior studies have demonstrated that the resistance to BAC of L. monocytogenes was associated with the prolonged survival of three strains of molecular serotype 1/2a in an Iberian pork processing plant. Because survival in such environments is related to biofilm formation, we hypothesised that the influence of BAC on the biofilm formation potential of L. monocytogenes might differ between BAC-resistant strains (BAC-R, MIC≥10mg/L) and BAC-sensitive strains (BAC-S, MIC≤2.5mg/L). To evaluate this possibility, three BAC-R strains and eight BAC-S strains, which represented all of the molecular serotype 1/2a strains detected in the sampled plant, were compared. Biofilm production was measured using the crystal violet staining method in 96-well microtitre plates. The BAC-R strains produced significantly (p <0.05) less biofilm than the BAC-S in the absence of BAC, independent of the rate of planktonic growth. In contrast, when the biofilm values were measured in the presence of BAC, one BAC-R strain (S10-1) was able to form biofilm at 5mg/L of BAC, which prevented biofilm formation among the rest of the strains. A genetic determinant of BAC resistance recently described in L. monocytogenes (Tn6188) was detected in S10-1. When a BAC-S strain and its spontaneous mutant BAC-R derivative were compared, resistance to BAC led to biofilm formation at 5mg/L of BAC and to a significant (p <0.05) stimulation of biofilm formation at 1.25mg/L of BAC, which significantly (p <0.05) reduced the biofilm level in the parent BAC-S strain. Our results suggest that the effect of subminimal inhibitory concentrations of BAC on biofilm production by L. monocytogenes might differ between strains with different MICs and even between resistant strains with similar MICs but different genetic determinants of BAC resistance. For BAC-R strains similar to S10-1, subminimal inhibitory BAC may represent an advantage, compensating for the weak biofilm formation level that might be associated with resistance. Biofilm formation in the presence of increased subminimal inhibitory concentrations of the disinfectant may represent an important attribute among certain resistant and persistent strains of L. monocytogenes.


      PubDate: 2014-09-01T18:44:46Z
       
  • L. monocytogenes in a cheese processing facility: Learning from
           contamination scenarios over three years of sampling
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): I. Rückerl , M. Muhterem-Uyar , S. Muri-Klinger , K.-H. Wagner , M. Wagner , B. Stessl
      The aim of this study was to analyze the changing patterns of Listeria monocytogenes contamination in a cheese processing facility manufacturing a wide range of ready-to-eat products. Characterization of L. monocytogenes isolates included genotyping by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Disinfectant-susceptibility tests and the assessment of L. monocytogenes survival in fresh cheese were also conducted. During the sampling period between 2010 and 2013, a total of 1284 environmental samples were investigated. Overall occurrence rates of Listeria spp. and L. monocytogenes were 21.9% and 19.5%, respectively. Identical L. monocytogenes genotypes were found in the food processing environment (FPE), raw materials and in products. Interventions after the sampling events changed contamination scenarios substantially. The high diversity of globally, widely distributed L. monocytogenes genotypes was reduced by identifying the major sources of contamination. Although susceptible to a broad range of disinfectants and cleaners, one dominant L. monocytogenes sequence type (ST) 5 could not be eradicated from drains and floors. Significantly, intense humidity and steam could be observed in all rooms and water residues were visible on floors due to increased cleaning strategies. This could explain the high L. monocytogenes contamination of the FPE (drains, shoes and floors) throughout the study (15.8%). The outcome of a challenge experiment in fresh cheese showed that L. monocytogenes could survive after 14days of storage at insufficient cooling temperatures (8 and 16°C). All efforts to reduce L. monocytogenes environmental contamination eventually led to a transition from dynamic to stable contamination scenarios. Consequently, implementation of systematic environmental monitoring via in-house systems should either aim for total avoidance of FPE colonization, or emphasize a first reduction of L. monocytogenes to sites where contamination of the processed product is unlikely. Drying of surfaces after cleaning is highly recommended to facilitate the L. monocytogenes eradication.


      PubDate: 2014-09-01T18:44:46Z
       
  • Development of a rapid capture-cum-detection method for Escherichia coli
           O157 from apple juice comprising nano-immunomagnetic separation in tandem
           with surface enhanced Raman scattering
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Roya Najafi , Shubhasish Mukherjee , Jim Hudson Jr. , Anup Sharma , Pratik Banerjee
      A combined capture and detection method comprising of nano-immunomagnetic separation (NIMS) and surface enhanced Raman spectroscopy (SERS) was developed to detect Escherichia coli O157 from liquid media including apple juice. The capture antibodies (cAbs) were immobilized on magnetite–gold (Fe3O4/Au) magnetic nanoparticles (MNPs) which were used for separation and concentration of the E. coli O157 cells from model liquid food matrix. The capture efficiency (CE) for E. coli O157 using MNP was found to be approximately 84–94%. No cross reactivity was observed with background non-target organisms. There was a significant difference in the mean CE of bacteria captured by MNP and commercially sourced immunomagnetic microbeads (p<0.05). For the detection of target pathogen, SERS labels were prepared by conjugating gold nanoparticles with Raman reporter molecules and the detector antibody (dAb). Au-Raman label-dAb was interacted with gold coated MNP-cAb-E. coli O157 complex. The ability of this immunoassay to detect E. coli O157 in apple juice was investigated. We have successfully applied the synthesized Fe3O4/Au nanoclusters to E. coli O157 detection in apple juice using the SERS method. The lowest detectable bacterial cell concentration in apple juice was 102 CFU/mL with a total analysis time of less than an hour. This method presents a convenient way of preconcentration, separation, and detection of low levels of target pathogen from liquid food matrix.


      PubDate: 2014-09-01T18:44:46Z
       
  • Thermal inactivation parameters of spores from different phylogenetic
           groups of Bacillus cereus
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Hue Luu-Thi , Dambar Bahadur Khadka , Chris W. Michiels
      The thermal inactivation kinetics of spores from 39 Bacillus cereus strains belonging to six different phylogenetic groups (group II to VII) was studied. Fresh spore suspensions in glass capillaries were heated in an oil bath at three or more different temperatures for five different times. Survival curves and thermal death curves were established and the kinetic parameters DT (decimal reduction time at temperature T) and z (temperature dependence of DT) were derived by linear regression. Most strains (38/39) had survival curves without a pronounced shoulder or tail, as reflected by linear regression coefficients R2 generally higher than 0.95. The heat resistance of the strains and groups of strains was then compared by determining the temperature (°C) at which logD=0.8 (TlogD=0.8). Spores from group VI strains showed significantly lower heat resistance than all other groups except group II, with TlogD=0.8 ranging between 82.7°C and 92.8°C. Spores from groups III and VII, on the other hand, were generally most heat resistant, with TlogD=0.8 between 91.9°C and 101.8°C. Further analysis revealed a positive correlation between spore heat resistance and both minimal and maximal growth temperatures of the strains. In contrast, the z value was negatively correlated with the minimal and maximal growth temperatures. The availability of genetic group-specific heat resistance data will contribute to a more accurate risk assessment of B. cereus.


      PubDate: 2014-09-01T18:44:46Z
       
  • Genetic approaches to chemotype determination in type B-trichothecene
           producing Fusaria
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Matias Pasquali , Quirico Migheli
      This review summarises the genetic methods used for chemotype determination of the main Fusarium type B-trichothecene producing species. Literature on Fusarium chemotype epidemiology over the last 15 years is reviewed in order to describe temporal and spatial chemotype distribution of these fungi worldwide. Genetic approaches used for chemotype determination are also reviewed and discussed, highlighting successes and potential pitfalls of the technique. Results from both genetic and chemical approaches are summarised to compare reliability, advantages and limitations of the two methods. Potential applications of genetic chemotyping to toxigenic Fusarium species are evaluated in the light of improving food safety of agricultural products. The use of chemotype determination in population studies, toxin prediction as well as for breeding purpose is described.


      PubDate: 2014-09-01T18:44:46Z
       
  • Effect of sporulation medium on wet-heat resistance and structure of
           Alicyclobacillus acidoterrestris DSM 3922-type strain spores and modeling
           of the inactivation kinetics in apple juice
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Celenk Molva , Ayse Handan Baysal
      Alicyclobacillus acidoterrestris is a spoilage bacterium in fruit juices leading to high economic losses. The present study evaluated the effect of sporulation medium on the thermal inactivation kinetics of A. acidoterrestris DSM 3922 spores in apple juice (pH3.82±0.01; 11.3±0.1 °Brix). Bacillus acidocaldarius agar (BAA), Bacillus acidoterrestris agar (BATA), malt extract agar (MEA), potato dextrose agar (PDA) and B. acidoterrestris broth (BATB) were used for sporulation. Inactivation kinetic parameters at 85, 87.5 and 90°C were obtained using the log-linear model. The decimal reduction times at 85°C (D 85°C) were 41.7, 57.6, 76.8, 76.8 and 67.2min; D 87.5°C-values were 22.4, 26.7, 32.9, 31.5, and 32.9min; and D 90°C-values were 11.6, 9.9, 14.7, 11.9 and 14.1min for spores produced on PDA, MEA, BATA, BAA and BATB, respectively. The estimated z-values were 9.05, 6.60, 6.96, 6.15, and 7.46, respectively. The present study suggests that the sporulation medium affects the wet-heat resistance of A. acidoterrestris DSM 3922 spores. Also, the dipicolinic acid content (DPA) was found highest in heat resistant spores formed on mineral containing media. After wet-heat treatment, loss of internal volume due to the release of DPA from spore core was observed by scanning electron microscopy. Since, there is no standardized media for the sporulation of A. acidoterrestris, the results obtained from this study might be useful to determine and compare the thermal resistance characteristics of A. acidoterrestris spores in fruit juices.


      PubDate: 2014-09-01T18:44:46Z
       
  • Phytic acid degrading lactic acid bacteria in tef-injera fermentation
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Maren M. Fischer , Ines M. Egli , Isabelle Aeberli , Richard F. Hurrell , Leo Meile
      Ethiopian injera, a soft pancake, baked from fermented batter, is preferentially prepared from tef (Eragrostis tef) flour. The phytic acid (PA) content of tef is high and is only partly degraded during the fermentation step. PA chelates with iron and zinc in the human digestive tract and strongly inhibits their absorption. With the aim to formulate a starter culture that would substantially degrade PA during injera preparation, we assessed the potential of microorganisms isolated from Ethiopian household-tef fermentations to degrade PA. Lactic acid bacteria (LAB) were found to be among the dominating microorganisms. Seventy-six isolates from thirteen different tef fermentations were analyzed for phytase activity and thirteen different isolates of seven different species were detected to be positive in a phytase screening assay. In 20-mL model tef fermentations, out of these thirteen isolates, the use of Lactobacillus (L.) buchneri strain MF58 and Pediococcus pentosaceus strain MF35 resulted in lowest PA contents in the fermented tef of 41% and 42%, respectively of its initial content. In comparison 59% of PA remained when spontaneously fermented. Full scale tef fermentation (0.6L) and injera production using L. buchneri MF58 as culture additive decreased PA in cooked injera from 1.05 to 0.34±0.02g/100g, representing a degradation of 68% compared to 42% in injera from non-inoculated traditional fermentation. The visual appearance of the pancakes was similar. The final molar ratios of PA to iron of 4 and to zinc of 12 achieved with L. buchneri MF58 were decreased by ca. 50% compared to the traditional fermentation. In conclusion, selected LAB strains in tef fermentations can degrade PA, with L. buchneri MF58 displaying the highest PA degrading potential. The 68% PA degradation achieved by the application of L. buchneri MF58 would be expected to improve human zinc absorption from tef-injera, but further PA degradation is probably necessary if iron absorption has to be increased.


      PubDate: 2014-09-01T18:44:46Z
       
  • Microbiological spoilage and investigation of volatile profile during
           storage of sea bream fillets under various conditions
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Foteini F. Parlapani , Athanasios Mallouchos , Serkos A. Haroutounian , Ioannis S. Boziaris
      Volatile organic compound (VOC) profile was determined during storage of sea bream (Sparus aurata) fillets under air and Modified Atmosphere Packaging (MAP — CO2/O2/N2: 60/10/30) at 0, 5 and 15°C. Microbiological, TVB-N (Total Volatile Base Nitrogen) and sensory changes were also monitored. Shelf-life of sea bream fillets stored under air was 14, 5 and 2days (d) at 0, 5 and 15°C respectively, while under MAP was 18, 8, and 2d at 0, 5 and 15°C respectively. At the end of shelf life, the total microbial population ranged from 7.5 to 8.5logcfu/g. Pseudomonas spp. were among the dominant spoilage microorganisms in all cases, however growth of Brochothrix thermosphacta and Lactic Acid Bacteria (LAB) were favoured under MAP compared to air. TVB-N production was favoured at higher temperatures and under air compared to lower temperatures and MAP. TVB-N increased substantially from the middle of storage and its value never reached concentrations higher than 30–35mgN/100g, which is the legislation limit, making it a poor chemical spoilage index (CSI). A lot of alcohols, aldehydes, ketones and ethyl esters that were detected in the present study have been reported as bacterial metabolites, others as products of chemical oxidation while others as aroma constituents. VOCs such as 3-methylbutanal, acetic acid, ethanol, ethyl esters of isovaleric and 2-methylbutyric acids, 1-penten-3-ol, 1-octen-3-ol and cis-4-heptenal appeared from the early or middle stages and increased until the end of storage. From those only 3-methylbutanal, acetic acid, ethanol and the ethyl esters have been reported as microbial origin, making them potential CSI candidates of sea bream fillets.


      PubDate: 2014-09-01T18:44:46Z
       
  • An educationally inspired illustration of two-dimensional Quantitative
           Microbiological Risk Assessment (QMRA) and sensitivity analysis
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): G.A. Vásquez , P. Busschaert , L.U. Haberbeck , M. Uyttendaele , A.H. Geeraerd
      Quantitative Microbiological Risk Assessment (QMRA) is a structured methodology used to assess the risk involved by ingestion of a pathogen. It applies mathematical models combined with an accurate exploitation of data sets, represented by distributions and – in the case of two-dimensional Monte Carlo simulations – their hyperparameters. This research aims to highlight background information, assumptions and truncations of a two-dimensional QMRA and advanced sensitivity analysis. We believe that such a detailed listing is not always clearly presented in actual risk assessment studies, while it is essential to ensure reliable and realistic simulations and interpretations. As a case-study, we are considering the occurrence of listeriosis in smoked fish products in Belgium during the period 2008–2009, using two-dimensional Monte Carlo and two sensitivity analysis methods (Spearman correlation and Sobol sensitivity indices) to estimate the most relevant factors of the final risk estimate. A risk estimate of 0.018% per consumption of contaminated smoked fish by an immunocompromised person was obtained. The final estimate of listeriosis cases (23) is within the actual reported result obtained for the same period and for the same population. Variability on the final risk estimate is determined by the variability regarding (i) consumer refrigerator temperatures, (ii) the reference growth rate of L. monocytogenes, (iii) the minimum growth temperature of L. monocytogenes and (iv) consumer portion size. Variability regarding the initial contamination level of L. monocytogenes tends to appear as a determinant of risk variability only when the minimum growth temperature is not included in the sensitivity analysis; when it is included the impact regarding the variability on the initial contamination level of L. monocytogenes is disappearing. Uncertainty determinants of the final risk indicated the need of gathering more information on the reference growth rate and the minimum growth temperature of L. monocytogenes. Uncertainty in the dose–response relationship was not included in the analysis, hence the level of its influence cannot be assessed in the present research. Finally, a baseline global workflow for QMRA and sensitivity analysis is proposed.


      PubDate: 2014-09-01T18:44:46Z
       
  • Microbial communities in air and wine of a winery at two consecutive
           vintages
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Fátima Pérez-Martín , Susana Seseña , Mónica Fernández-González , María Arévalo , María Llanos Palop
      The aim of this study was to assess, both quantitatively and qualitatively, the populations of lactic acid bacteria (LAB) and yeasts in air and wine of a winery, in order to evaluate the possible exchange of microorganisms between them. Samples were taken in a winery located in Castilla-La Mancha (Spain) during the winemaking period of two consecutive vintages (2011 and 2012). The microbial composition was determined by using both a culture-dependent method and a culture-independent method, PCR-denaturing gradient gel electrophoresis (PCR-DGGE). In addition, genetic characterization of isolates from plates was carried out. A high diversity of species was detected in air and wine samples from both vintages. Leuconostoc mesenteroides was the predominant lactic acid bacteria in air from both vintages while Oenococcus oeni was the predominant in wine. Saccharomyces cerevisiae was the most frequently isolated yeast in both air and wine. Typing of O. oeni and S. cerevisiae isolates from air and wine samples showed the presence of coincident genotypes in both samples, that would confirm the exchange of microorganisms between the two environments, air and wine, and furthermore some of these genotypes were also found at samples taken at different vintages, indicating that they would remain in the winery. The results display the influence of the activity taking place in the winery and the moment of fermentation of the wines in tanks, on the microorganisms present in the air and the role of the air for the dispersal of microorganisms within the winery.


      PubDate: 2014-09-01T18:44:46Z
       
  • Wild Saccharomyces cerevisiae strains display biofilm-like morphology in
           contact with polyphenols from grapes and wine
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Rossana Sidari , Andrea Caridi , Kate S. Howell
      Polyphenols are a major component of wine grapes, and contribute to color and flavor, but their influence upon yeast growth forms has not been investigated. In this work we have studied the effect of polyphenols on the ability of natural isolates of wine-related Saccharomyces cerevisiae strains to form biofilms attaching to plastic surfaces, to grow as mat colonies, to invade media, and to display filamentous growth. The use of carbon- and nitrogen-rich or deficient media simulated grape juice fermentation conditions. The addition of wine polyphenols to these media affected biofilm formation, and cells exhibited a wide variety of invasiveness and mat formation ability with associated different growth and footprint patterns. Microscopic observation revealed that some strains switched to filamentous phenotypes which were able to invade media. The wide range of phenotypic expression observed could have a role in selection of strains suitable for inoculated wine fermentations and may explain the persistence of yeast strains in vineyard and winery environments.


      PubDate: 2014-09-01T18:44:46Z
       
  • Potential uptake of Escherichia coli O157:H7 and Listeria monocytogenes
           from growth substrate into leaves of salad plants and basil grown in soil
           irrigated with contaminated water
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Walter Chitarra , Lucia Decastelli , Angelo Garibaldi , Maria Lodovica Gullino
      Outbreaks of foodborne illness, resulting from the consumption of fresh produce contaminated with human pathogens, are increasing. Potential uptake and persistence of human pathogens within edible parts of consumed fresh vegetables become an important issue in food safety. This study was conducted to assess the potential uptake and internalization of Escherichia coli O157:H7 and Listeria monocytogenes from an autoclaved substrate into edible parts of basil and baby salad plants (lettuce, cultivated rocket, wild rocket and corn salad) from 20 to 60–80days after inoculation, when plants are ready to be harvested and commercialized. Plants were grown in mesocosms under different temperature conditions (24°C and 30°C) and the growing substrate was inoculated using contaminated irrigation water (7logCFU/mL). E. coli O157:H7 could be internalized in the leaves of the tested leafy vegetables through the roots and persist up to the harvesting time with negligible differences between 24°C and 30°C. Significant decreases in pathogen titers were observed over time in the growing substrate on which the plants grew, until the last sampling time. In contrast, L. monocytogenes internalized and persisted only in lettuce mesocosms at 24°C. Neither pathogen was observed in basil leaves. Similarly, in basil growing substrates, enteric bacteria were undetectable at the end of the experiments, suggesting that basil plants may produce and release antimicrobial compounds active against both bacteria in root exudates. These results suggest that enteric bacteria are able to persist within baby salad leaves up to market representing a risk for consumer's health.


      PubDate: 2014-09-01T18:44:46Z
       
  • Contribution of endogenous plant myrosinase to the antimicrobial activity
           of deodorized mustard against Escherichia coli O157:H7 in fermented dry
           sausage
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Roniele Peixoto Cordeiro , Chen Wu , Richard Alan Holley
      This work investigated the antimicrobial activity of residual endogenous plant myrosinase in Oriental and yellow mustard powders and a deoiled meal (which contained more glucosinolate than unextracted mustard powder of each type of mustard), against Escherichia coli O15:H7 during dry-fermented sausage ripening. When small amounts of “hot” mustard powder or meal containing endogenous plant myrosinase were added to fully-deodorized powders and a meal of the same type, pathogen reduction rates were enhanced. The higher glucosinolate level in the deoiled mustard meal enabled the use of 50% less mustard in dry sausage to achieve the mandatory ≥5logCFU/g reduction of E. coli O157:H7. The myrosinase-like activity present in E. coli O157:H7 contributed to glucosinolate hydrolysis in sausages with fully-deodorized, deoiled mustard meal, although the period necessary for a 5log pathogen reduction was 14d longer. Yellow mustard derivatives were more potently antimicrobial than Oriental mustard.


      PubDate: 2014-09-01T18:44:46Z
       
  • Oxygenated monoterpenes citral and carvacrol cause oxidative damage in
           Escherichia coli without the involvement of tricarboxylic acid cycle and
           Fenton reaction
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Beatriz Chueca , Rafael Pagán , Diego García-Gonzalo
      Oxygenated monoterpenes citral and carvacrol are common constituents of many essential oils (EOs) that have been extensively studied as antimicrobial agents but whose mechanisms of microbial inactivation have not been totally elucidated. A recent study described a mechanism of Escherichia coli death for (+)-limonene, a hydrocarbon monoterpene also frequently present in EOs, similar to the common mechanism proposed for bactericidal antibiotics. This mechanism involves the formation of Fenton-mediated hydroxyl radical, a reactive oxygen species (ROS), via tricarboxylic acid (TCA) cycle, which would ultimately inactivate cells. Our objective was to determine whether E. coli MG1655 inactivation by citral and carvacrol follows a similar mechanism of cell death. Challenging experiments with 300μL/L citral and 100μL/L carvacrol inactivated at least 2.5log10 cycles of exponentially growing cells in 3h under aerobic conditions. The presence of thiourea (an ROS scavenger) reduced cell inactivation in 2log10 cycles, demonstrating the role of ROS in cell death. Decreased resistance of a ΔrecA mutant (deficient in an enzyme involved in SOS response to DNA damage) indicated that citral and carvacrol caused oxidative damage to DNA. Although the mechanism of E. coli inactivation by carvacrol and citral was similarly mediated by ROS, their formation did not follow the same pathways described for (+)-limonene and bactericidal drugs because neither Fenton reaction nor NADH production via the TCA cycle was involved in cell death. Moreover, further experiments demonstrated antimicrobial activity of citral and carvacrol in anaerobic environments without the involvement of ROS. As a consequence, cell death by carvacrol and citral in anaerobiosis follows a different mechanism than that observed under aerobic conditions. These results demonstrated a different mechanism of inactivation by citral and carvacrol with regard to (+)-limonene and bactericidal antibiotics, indicating the complexity of the mechanisms of bacterial inactivation among EO constituents. Advancements in the description of these mechanisms will help in extending and improving the use of these compounds as natural antimicrobials.


      PubDate: 2014-09-01T18:44:46Z
       
  • Bovicin HC5 and nisin reduce Staphylococcus aureus adhesion to polystyrene
           and change the hydrophobicity profile and Gibbs free energy of adhesion
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Natan de Jesus Pimentel-Filho , Mayra Carla de Freitas Martins , Guilherme Bicalho Nogueira , Hilário Cuquetto Mantovani , Maria Cristina Dantas Vanetti
      Staphylococcus aureus is an opportunistic pathogen often multidrug-resistant that not only causes a variety of human diseases, but also is able to survive on biotic and abiotic surfaces through biofilm communities. The best way to inhibit biofilm establishment is to prevent cell adhesion. In the present study, subinhibitory concentrations of the bacteriocins bovicin HC5 and nisin were tested for their capability to interfere with the adhesion of S. aureus to polystyrene. Subinhibitory dosages of the bacteriocins reduced cell adhesion and this occurred probably due to changes in the hydrophobicity of the bacterial cell and polystyrene surfaces. After treatment with bovicin HC5 and nisin, the surfaces became more hydrophilic and the free energy of adhesion (∆G adhesion) between bacteria and the polystyrene surface was unfavorable. The transcriptional level of selected genes was assessed by RT-qPCR approach, revealing that the bacteriocins affected the expression of some important biofilm associated genes (icaD, fnbA, and clfB) and rnaIII, which is involved in the quorum sensing mechanism. The conditioning of food-contact surfaces with bacteriocins can be an innovative and powerful strategy to prevent biofilms in the food industry. The results are relevant for food safety as they indicate that bovicin HC5 and nisin can inhibit bacterial adhesion and consequent biofilm establishment, since cell adhesion precedes biofilm formation.


      PubDate: 2014-09-01T18:44:46Z
       
  • Benzalkonium chloride and heavy-metal tolerance in Listeria monocytogenes
           from retail foods
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Dongyang Xu , Yanli Li , M. Shamim Hasan Zahid , Shinji Yamasaki , Lei Shi , Jian-rong Li , He Yan
      Phenotypic and genotypic tolerance in 71 Listeria monocytogenes isolates from different varieties of foods to benzalkonium chloride (BC) and cadmium were investigated by susceptibility test and molecular methods. To investigate the role of efflux pumps in BC tolerance, reserpine, an efflux pump inhibitor, was added to the BC tolerant strains. Tolerance to BC and cadmium were 26.8% (19/71) and 49.3% (35/71) respectively. Strains with BC tolerance were significantly more frequent among those of serotype 4b (100%, 6/6) than among those of serotype 1/2a (or 3a) (13.5%, 5/37), which represent the predominant number of strains (52.1%, 37/71). Tolerance to cadmium was encountered among 62.2% (23/37) and 50.0% (3/6) of the serotype 1/2a (or 3a) and 4b strains, respectively, and among 19.0% (4/21) of the strains of the serotype 1/2c. All of the 10 (14.1%) isolates found to be BC and cadmium co-tolerance were isolated from raw meat or quick-frozen food made of wheat flour and rice. Five multi-drug resistant strains were tolerant to cadmium as well. Among 71 isolates examined, one contained qacA and three contained qacEΔ1-sul. To the best of our knowledge, this is the first detection of qacA and qacEΔ1-sul in L. monocytogenes, an indication of the possible horizontal transfer of the two genes. Addition of reserpine to the tolerant strains resulted in the loss of tolerance among seven out of 19 BC strains, suggesting a certain role the efflux pump played in mediating BC tolerance. Of the three distinct cadA types known to date in L. monocytogenes, the cadA1 and cadA2 genes were detected among 24 (33.8%) and three (4.2%) isolates respectively. The presence of cadA1 and cadA2 largely corresponded to the susceptibility phenotype. A subset (9/35 [25.7%]) of the cadmium-tolerant isolates lacked the known cadmium resistance determinants. These findings suggest that food products could act as a reservoir for L. monocytogenes harboring tolerance to BC and cadmium and will further our understanding of the adaptations of this organism to these two compounds.


      PubDate: 2014-09-01T18:44:46Z
       
  • Control of tyramine and histamine accumulation by lactic acid bacteria
           using bacteriocin forming lactococci
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Giulia Tabanelli , Chiara Montanari , Eleonora Bargossi , Rosalba Lanciotti , Veronica Gatto , Giovanna Felis , Sandra Torriani , Fausto Gardini
      The aim of this study was to evaluate the competitive effects of three bacteriocin producing strains of Lactococcus lactis subsp. lactis against two aminobiogenic lactic acid bacteria, i.e. the tyramine producing strain Enterococcus faecalis EF37 and the histamine producing strain Streptococcus thermophilus PRI60, inoculated at different initial concentrations (from 2 to 6logcfu/ml). The results showed that the three L. lactis subsp. lactis strains were able to produce bacteriocins: in particular, L. lactis subsp. lactis VR84 and EG46 produced, respectively, nisin Z and lacticin 481, while for the strains CG27 the bacteriocin has not been yet identified, even if its peptidic nature has been demonstrated. The co-culture of E. faecalis EF37 in combination with lactococci significantly reduced the growth potential of this aminobiogenic strain, both in terms of growth rate and maximum cell concentration, depending on the initial inoculum level of E. faecalis. Tyramine accumulation was strongly reduced when E. faecalis EF37 was inoculated at 2logcfu/ml and, to a lesser extent, at 3logcfu/ml, as a result of a lower cell load of the aminobiogenic strain. All the lactococci were more efficient in inhibiting streptococci in comparison with E. faecalis EF37; in particular, L. lactis subsp. lactis VR84 induced the death of S. thermophilus PRI60 and allowed the detection of histamine traces only at higher streptococci inoculum levels (5–6logcfu/ml). The other two lactococcal strains did not show a lethal action against S. thermophilus PRI60, but were able to reduce its growth extent and histamine accumulation, even if L. lactis subsp. lactis EG46 was less effective when the initial streptococci concentration was 5 and 6logcfu/ml. This preliminary study has clarified some aspects regarding the ratio between bacteriocinogenic strains and aminobiogenic strains with respect to the possibility to accumulate BA and has also showed that different bacteriocins can have different effects on BA production on the same strain. This knowledge is essentially aimed to use bacteriocinogenic lactococci as a predictable strategy against aminobiogenic bacteria present in cheese or other fermented foods.


      PubDate: 2014-09-01T18:44:46Z
       
  • Removal of Salmonella enterica Enteritidis and Escherichia coli from green
           peppers and melons by ultrasound and organic acids
    • Abstract: Publication date: 3 November 2014
      Source:International Journal of Food Microbiology, Volume 190
      Author(s): Jackline Freitas Brilhante de São José , Hiasmyne Silva de Medeiros , Patrícia Campos Bernardes , Nélio José de Andrade
      The aim of this study was to evaluate the effectiveness of ultrasound treatment combined with organic acids in the decontamination step for green peppers and melons. The influence of the surface roughness of the peppers and melons on bacterial adhesion was evaluated, as measured using a profilometer. The adhesion of Salmonella enterica serovar Enteritidis and Escherichia coli to the green pepper and melon surfaces was also evaluated by measuring the hydrophobicity of the microorganisms and the surfaces. The bacteria that adhered to the surface of green peppers and melons was quantified by plate count and visualized by scanning electron microscopy. In addition, the efficiency of ultrasound and organic acids to remove bacteria from the pepper and melon surfaces was examined. The average roughness (R a) of the green peppers (13.0±2.7nm) was significantly different (p >0.05) from the melons (33.5±7.9nm). Adherence of S. Enteritidis and E. coli are thermodynamically unfavorable for both surfaces studied (∆G adhesion >0). Despite these data, good adhesion occurred on both surfaces. The number of bacteria on green pepper slices was 7.3 and 7.0logCFU/cm2 for E. coli and S. enterica Enteritidis, respectively. For melon surfaces, the number of bacteria was 7.0 and 6.9logCFU/cm2 for E. coli and S. Enteritidis, respectively. The greater adherence of both bacteria on the green peppers can be explained by its hydrophobic surface; the hydrophilic surfaces of melons resulted in lower adherence. These results suggest that the adhesion observed in this experiment is a multifactorial process. Among the treatments evaluated for green peppers, a higher removal of pathogens was observed after use of a combination of ultrasound and 1% lactic acid; this treatment reduced E. coli and Salmonella by 2.9 and 2.8logCFU/cm2, respectively. For melons, the combination of ultrasound and lactic acid showed a reduction of 2.5 and 3.1logCFU/cm2 for E. coli and S. Enteritidis, respectively. These results indicate that it is possible to replace the chlorinated compounds that are commonly used to sanitize fruits and vegetables. These results confirm that ultrasound, an emerging technology for food processing applications, could enhance the microbial safety of fresh produce.


      PubDate: 2014-09-01T18:44:46Z
       
  • Shedding of Salmonella in single age caged commercial layer flock at an
           early stage of lay
    • Abstract: Publication date: 17 October 2014
      Source:International Journal of Food Microbiology, Volume 189
      Author(s): Vaibhav C. Gole , Charles G.B. Caraguel , Margaret Sexton , Chelsea Fowler , Kapil K. Chousalkar
      The shedding of Salmonella in a single age commercial egg layer flock was investigated at the onset of lay (18weeks) followed by two longitudinal samplings at 24 and 30weeks. At the age of 18weeks, when the first sampling was performed, the prevalence of Salmonella in faeces was 82.14% whereas all egg belt and dust samples were Salmonella positive by culture method. In later samplings, at the age of 24 and 30weeks, the prevalence of Salmonella in faeces was significantly reduced (p<0.001) to 38.88% and 12.95% respectively, however all egg belt and dust samples remained positive by culture method. The prevalence of Salmonella in faeces collected from the low tier cages was significantly higher (p=0.009) as compared with samples from the high tier cages. In all types of samples processed by culture method, S. Mbandaka was the most frequently (54.40%) isolated serovar followed by S. Worthington (37.60%), S. Anatum (0.8%), and S. Infantis (0.8%). All samples were also tested by real-time PCR method. The observed agreement between culture method and real-time PCR in detecting Salmonella-positive dust and egg belt samples was 100%. There was almost perfect agreement (observed agreement=99.21%) for the detection of Salmonella-positive eggshells. Observed agreement between culture method and real-time PCR for detecting Salmonella-positive shoe cover and faecal samples was, however, moderate (80%) and low (54.27%) respectively. Real-time PCR results showed that there was a significant increase in the load of Salmonella on egg belt, dust and shoe cover samples at the 24 and 30weeks of lay as compared to the 18weeks of lay. Real-time PCR provided a more rapid and reliable method of detection of Salmonella on all dry sample types whereas the traditional culture method proved much more reliable when trying to detect Salmonella in wet faecal samples.


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




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


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


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


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


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


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


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


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


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


      PubDate: 2014-08-12T17:38:59Z
       
 
 
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