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  Subjects -> BIOLOGY (Total: 2974 journals)
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MICROBIOLOGY (254 journals)                  1 2     

Showing 1 - 0 of 0 Journals sorted alphabetically
Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 5)
Addiction Genetics     Open Access   (Followers: 5)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 19)
Advances in Microbiology     Open Access   (Followers: 18)
Advances in Molecular Imaging     Open Access   (Followers: 1)
African Journal of Clinical and Experimental Microbiology     Open Access  
African Journal of Microbiology Research     Open Access   (Followers: 1)
Algorithms for Molecular Biology     Open Access   (Followers: 4)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 17)
American Journal of Microbiological Research     Open Access   (Followers: 2)
American Journal of Microbiology     Open Access   (Followers: 13)
American Journal of Molecular Biology     Open Access   (Followers: 2)
American Journal of Stem Cell Research     Open Access   (Followers: 3)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 7)
Annals of Microbiology     Hybrid Journal   (Followers: 9)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 35)
Antimicrobial Agents and Chemotherapy     Hybrid Journal   (Followers: 21)
Antiviral Research     Hybrid Journal   (Followers: 7)
Applied and Environmental Microbiology     Hybrid Journal   (Followers: 42)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 17)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 61)
Aquatic Microbial Ecology     Hybrid Journal   (Followers: 3)
Archives of Microbiology     Hybrid Journal   (Followers: 7)
Avicenna Journal of Clinical Microbiology and Infection     Open Access   (Followers: 1)
Bangladesh Journal of Medical Microbiology     Open Access   (Followers: 1)
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
Bio-Research     Full-text available via subscription   (Followers: 1)
BioArchitecture     Full-text available via subscription  
Bioethanol     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 8)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Biomolecular Detection and Quantification     Open Access  
Biomolecules     Open Access   (Followers: 1)
Biotechnology and Molecular Biology Reviews     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 8)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases and Medical Microbiology     Open Access   (Followers: 2)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 3)
Cell Biology : Research & Therapy     Hybrid Journal   (Followers: 3)
Cell Host & Microbe     Full-text available via subscription   (Followers: 15)
Cell Medicine     Open Access   (Followers: 3)
Cell Regeneration     Open Access   (Followers: 1)
Cell Stem Cell     Full-text available via subscription   (Followers: 32)
CellBio     Open Access  
Cells     Open Access   (Followers: 2)
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 11)
Cellular and Molecular Biology Letters     Open Access   (Followers: 1)
Cellular and Molecular Life Sciences (CMLS)     Hybrid Journal   (Followers: 6)
Cellular Microbiology     Hybrid Journal   (Followers: 7)
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (Followers: 2)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (Followers: 17)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 5)
Clinical Microbiology Reviews     Hybrid Journal   (Followers: 16)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 10)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 11)
Current Clinical Microbiology Reports     Hybrid Journal   (Followers: 1)
Current Issues in Molecular Biology     Open Access   (Followers: 2)
Current Microbiology     Hybrid Journal   (Followers: 9)
Current Molecular Biology Reports     Hybrid Journal   (Followers: 1)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 30)
Current Tissue Engineering     Hybrid Journal   (Followers: 2)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 8)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 8)
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: 14)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 4)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 14)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 5)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 17)
European Journal of Microbiology and Immunology     Open Access   (Followers: 8)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 4)
Experimental Cell Research     Hybrid Journal   (Followers: 7)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 8)
Fems Microbiology Letters     Hybrid Journal   (Followers: 18)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 23)
Fermentation     Open Access   (Followers: 1)
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 15)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 3)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 3)
Frontiers in Cellular Neuroscience     Open Access   (Followers: 8)
Frontiers in Microbiology     Open Access   (Followers: 8)
Frontiers in Molecular Neuroscience     Open Access   (Followers: 4)
Future Microbiology     Hybrid Journal   (Followers: 4)
Future Virology     Hybrid Journal   (Followers: 7)
Gene Expression     Full-text available via subscription  
Genetica si Biologie Moleculara     Open Access  
Genetics and Molecular Research     Open Access   (Followers: 4)
Geomicrobiology Journal     Hybrid Journal   (Followers: 2)
Gut Microbes     Full-text available via subscription   (Followers: 8)
IAWA Journal     Hybrid Journal  
Indian Journal of Microbiology     Hybrid Journal   (Followers: 2)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 3)
Inside the Cell     Open Access  
International Journal of Antimicrobial Agents     Hybrid Journal   (Followers: 7)
International Journal of Bacteriology     Open Access  
International Journal of Bioassays     Open Access   (Followers: 2)
International Journal of Biotechnology and Molecular Biology Research     Open Access   (Followers: 2)
International Journal of Food Microbiology     Hybrid Journal   (Followers: 12)
International Journal of Genetics and Molecular Biology     Open Access  
International Journal of Infection and Microbiology     Open Access   (Followers: 1)
International Journal of Medical Microbiology     Hybrid Journal   (Followers: 7)
International Journal of Molecular Medicine     Full-text available via subscription   (Followers: 5)
International Journal of Mycobacteriology     Open Access  
International Journal of Systematic and Evolutionary Microbiology     Full-text available via subscription   (Followers: 3)
International Journal of Virology and Molecular Biology     Open Access  
International Microbiology     Open Access   (Followers: 3)
Invertebrate Immunity     Open Access   (Followers: 1)
JMM Case Reports     Open Access  
Journal of Cell Science & Therapy     Open Access   (Followers: 2)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 2)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 2)
Journal of Applied Microbiology     Hybrid Journal   (Followers: 12)
Journal of Bacteriology     Hybrid Journal   (Followers: 28)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 3)
Journal of Biomolecular Structure and Dynamics     Hybrid Journal   (Followers: 2)
Journal of Bionanoscience     Full-text available via subscription  
Journal of Brewing and Distilling     Open Access   (Followers: 1)
Journal of Cell and Animal Biology     Open Access  
Journal of Cell Biology and Genetics     Open Access   (Followers: 2)
Journal of Clinical Microbiology     Hybrid Journal   (Followers: 28)
Journal of Clinical Pathology     Full-text available via subscription   (Followers: 10)
Journal of Extracellular Vesicles     Open Access   (Followers: 4)
Journal of Food Microbiology     Open Access   (Followers: 3)
Journal of General and Molecular Virology     Open Access  
Journal of Genes and Cells     Open Access  
Journal of Global Antimicrobial Resistance     Hybrid Journal   (Followers: 2)
Journal of Industrial Microbiology and Biotechnology     Hybrid Journal   (Followers: 14)
Journal of Medical Microbiology     Full-text available via subscription   (Followers: 4)
Journal of Microbiological Methods     Hybrid Journal   (Followers: 2)
Journal of Microbiology     Hybrid Journal   (Followers: 7)
Journal of Microbiology and Antimicrobials     Open Access   (Followers: 2)
Journal of Microbiology Research     Open Access   (Followers: 2)
Journal of Micropalaeontology     Hybrid Journal   (Followers: 7)
Journal of Molecular Biochemistry     Open Access   (Followers: 3)
Journal of Molecular Biology Research     Open Access   (Followers: 3)
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 12)
Journal of Molecular Pathophysiology     Open Access   (Followers: 1)
Journal of Molecular Psychiatry     Open Access   (Followers: 9)
Journal of Morphology     Hybrid Journal   (Followers: 4)
Journal of Pharmacy & Bioresources     Full-text available via subscription   (Followers: 3)
Journal of Plant Molecular Biology and Biotechnology     Open Access   (Followers: 7)
Journal of Plant Pathology & Microbiology     Open Access  
Journal of Proteome Science and Computational Biology     Open Access  
Journal of Regenerative Medicine and Tissue Engineering     Open Access   (Followers: 3)
Journal of The Academy of Clinical Microbiologists     Open Access  
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 2)
Journal of the Institute of Brewing     Free   (Followers: 1)
Journal of Tropical Microbiology and Biotechnology     Full-text available via subscription  
Jundishapur Journal of Microbiology     Open Access  
Letters In Applied Microbiology     Hybrid Journal   (Followers: 5)
Macrophage     Open Access  
MAP Kinase     Open Access  
Medical Mycology     Open Access   (Followers: 5)
Memórias do Instituto Oswaldo Cruz     Open Access  
Methods in Molecular Biology     Hybrid Journal   (Followers: 24)
Microbes and Health     Open Access   (Followers: 1)
Microbes and Infection     Full-text available via subscription   (Followers: 4)
Microbial Biotechnology     Open Access   (Followers: 8)
Microbial Cell Factories     Open Access   (Followers: 7)
Microbial Drug Resistance     Hybrid Journal   (Followers: 4)
Microbial Ecology     Hybrid Journal   (Followers: 8)
Microbial Ecology in Health and Disease     Open Access  
Microbial Informatics and Experimentation     Open Access   (Followers: 1)
Microbial Pathogenesis     Hybrid Journal   (Followers: 7)
Microbial Risk Analysis     Full-text available via subscription  
Microbiologia Medica     Open Access   (Followers: 1)
Microbiological Research     Hybrid Journal   (Followers: 6)
Microbiology     Hybrid Journal   (Followers: 12)
Microbiology (SGM)     Full-text available via subscription   (Followers: 16)
Microbiology and Immunology     Hybrid Journal   (Followers: 10)
Microbiology and Molecular Biology Reviews     Hybrid Journal   (Followers: 22)
Microbiology Australia     Hybrid Journal  
Microbiology Discovery     Open Access  
Microbiology Indonesia     Open Access  
Microbiology Research     Open Access   (Followers: 7)
MicrobiologyOpen     Open Access   (Followers: 2)
Microbiome     Hybrid Journal   (Followers: 6)
Microbiome Science and Medicine     Open Access  
Microorganisms     Open Access   (Followers: 2)
MicroRNA     Hybrid Journal   (Followers: 1)
Molecular and Cellular Therapies     Open Access  
Molecular Biology and Genetic Engineering     Open Access   (Followers: 1)
Molecular Biology Research Communications     Open Access   (Followers: 1)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 2)
Molecular Genetics, Microbiology and Virology     Hybrid Journal   (Followers: 6)
Molecular Imaging     Open Access  
Molecular Imaging and Biology     Hybrid Journal   (Followers: 2)
Molecular Medicine     Open Access   (Followers: 1)
Molecular Medicine Reports     Full-text available via subscription   (Followers: 6)
Molecular Microbiology     Hybrid Journal   (Followers: 28)
Molecular Oral Microbiology     Partially Free   (Followers: 3)

        1 2     

Journal Cover International Journal of Food Microbiology
  [SJR: 1.64]   [H-I: 142]   [12 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0168-1605
   Published by Elsevier Homepage  [3039 journals]
  • Effect of chitosan and SO2 on viability of Acetobacter strains in wine
    • Authors: Maria José Valera; Florencia Sainz; Albert Mas; María Jesús Torija
      Pages: 1 - 4
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Maria José Valera, Florencia Sainz, Albert Mas, María Jesús Torija
      Wine spoilage is an important concern for winemakers to preserve the quality of their final product and avoid contamination throughout the production process. The use of sulphur dioxide (SO2) is highly recommended to prevent wine spoilage due to its antimicrobial activity. However, SO2 has a limited effect on the viability of acetic acid bacteria (AAB). Currently, the use of SO2 alternatives is favoured in order to reduce the use of chemicals and improve stabilization in winemaking. Chitosan is a biopolymer that is approved by the European authorities and the International Organization of Vine and Wine to be used as a fining agent and antimicrobial in wines. However, its effectiveness in AAB prevention has not been studied. Two strains of Acetobacter, adapted to high ethanol environments, were analysed in this study. Both chitosan and SO2 effects were compared in artificially contaminated wines. Both molecules reduced the metabolic activity of both AAB strains. Although AAB populations were detected by culture independent techniques, their numbers were reduced with time, and their viability decreased following the application of both products, especially with chitosan.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.022
      Issue No: Vol. 246 (2017)
       
  • Experimental effect of ozone upon the microbial flora of commercially
           produced dairy fermented products
    • Authors: A. Alexopoulos; S. Plessas; Y. Kourkoutas; C. Stefanis; S. Vavias; C. Voidarou; I. Mantzourani; E. Bezirtzoglou
      Pages: 5 - 11
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): A. Alexopoulos, S. Plessas, Y. Kourkoutas, C. Stefanis, S. Vavias, C. Voidarou, I. Mantzourani, E. Bezirtzoglou
      Ozone was used to control spoilage microorganisms during the manufacturing of dairy products. Ozone stream was applied onto the surface of freshly filled yoghurt cups just before storage for curd development in order to prevent cross contamination from spoilage airborne microorganisms. Accordingly, brine solution was bubbled with ozone for various periods of time and used for ripening of white (feta type) cheese. Both products were subjected to a continuous monitoring of microbial load and also tested for their sensorial properties. In ozonated yoghurt samples there was a reduction in mould counts of approximately 0.6Logcfu/g (25.1%) by the end of the monitoring period in relation to the control samples. In white cheese ripened with ozonated brine (1.3mg/L O3, NaCl 5%) it seems that ozone treatment during the two months of observation reduced some of the mould load but without offering any advantages over the use of traditional brine (NaCl 7%). However, some sensorial alterations were observed, probably due to the organic load in the brine which deactivates ozone in early stages of application. It is concluded that, if the factors of time and concentration of ozone are configured properly, ozonation could be a promising approach safeguarding the production of some dairy products.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.018
      Issue No: Vol. 246 (2017)
       
  • Phage-host interactions analysis of newly characterized Oenococcus oeni
           bacteriophages: Implications for malolactic fermentation in wine
    • Authors: Antonella Costantini; Francesca Doria; Juan-Carlos Saiz; Emilia Garcia-Moruno
      Pages: 12 - 19
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Antonella Costantini, Francesca Doria, Juan-Carlos Saiz, Emilia Garcia-Moruno
      Nowadays, only few phages infecting Oenococcus oeni, the principal lactic acid bacteria (LAB) species responsible for malolactic fermentation (MLF) in wine, have been characterized. In the present study, to better understanding the factors affecting the lytic activity of Oenococcus phages, fifteen O. oeni bacteriophages have been studied in detail, both with molecular and microbiological methods. No correlations were found between genome sizes, type of integrase genes, or morphology and the lytic activity of the 15 tested phages. Interestingly, though phage attack in a wine at the end of alcoholic fermentation seems not to be a problem, it can indeed represent a risk factor for MLF when the alcohol content is low, feature that may be a key point for choosing the appropriate time for malolactic starter inoculation. Additionally, it was observed that some phages genomes bear 2 or 3 types of integrase genes, which point to horizontal gene transfer between O. oeni bacteriophages.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.020
      Issue No: Vol. 246 (2017)
       
  • Staphylococcal ecosystem of kitoza, a traditional malagasy meat product
    • Authors: Angela Ratsimba; Sabine Leroy; Jean Paul Chacornac; Danielle Rakoto; Elodie Arnaud; Victor Jeannoda; Régine Talon
      Pages: 20 - 24
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Angela Ratsimba, Sabine Leroy, Jean Paul Chacornac, Danielle Rakoto, Elodie Arnaud, Victor Jeannoda, Régine Talon
      Kitoza is a traditional meat product from Madagascar manufactured with strips of pork or beef. The process includes a first step of salting and mixing with spices followed by sun-drying or smoking step. As salting and drying select coagulase-negative staphylococci (CNS), our aim was to identify the CNS species in kitoza with the objective in the future of developing indigenous starters. Microbial analyses revealed that the only pathogenic bacterium enumerated was Staphylococcus aureus, which was found in 54% of the samples. The level of Enterobacteriaceae revealed a rather good hygienic quality of these products. CNS were confirmed in all the samples at high levels ranging from 5 to 7logcfu/g. Identification of CNS species in a large collection of 829 isolates revealed 9 identified species, 7 for beef and 8 for pork kitoza. There were significant difference in the distribution of CNS species according to the type of meat and the process. Staphylococcus saprophyticus was the dominant species for sun-dried or smoked beef and sun-dried pork kitoza (73–75%), while for smoked pork kitoza Staphylococcus equorum (26%), S. saprophyticus (23%), Staphylococcus succinus (23%) and Staphylococcus epidermidis (17%) co-dominated. Some CNS could be used as indigenous starters in particular to compete against S. aureus.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.02.001
      Issue No: Vol. 246 (2017)
       
  • Survey of Penicillia associated with Italian grana cheese
    • Authors: S. Decontardi; A. Mauro; N. Lima; P. Battilani
      Pages: 25 - 31
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): S. Decontardi, A. Mauro, N. Lima, P. Battilani
      The present work aimed to contribute information on the mycobiota associated with ripening grana cheese, with focus on the genus Penicillium as potential mycotoxin producers. Eighteen wheels of grana cheese, aged in different storehouses situated in Northern Italy, were sampled to isolate associated fungi. Penicillium spp. were commonly dominant; morphological observation and gene sequencing were applied to identify Penicillium at species level. P. crustosum and P. solitum were the dominant species. Citrinin and ochratoxin A mycotoxins were analysed and the latter was found in all grana cheese samples. These results confirmed that a polyphasic approach is mandatory for Penicillium identification at species level.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.019
      Issue No: Vol. 246 (2017)
       
  • Genetic and biochemical characterization of an oligo-α-1,6-glucosidase
           from Lactobacillus plantarum
    • Authors: Susana Delgado; Ana Belén Flórez; Lucía Guadamuro; Baltasar Mayo
      Pages: 32 - 39
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Susana Delgado, Ana Belén Flórez, Lucía Guadamuro, Baltasar Mayo
      Although encoded in the genome of many Lactobacillus spp. strains, α-glucosidases have received little attention compared to other glycosyl hydrolases. In this study, a putative oligosaccharide(oligo)-α-1,6-glucosidase-encoding gene (malL) was identified in the genome of Lactobacillus plantarum LL441. malL coded for 572 amino acid residues with a calculated total molecular mass of 66.31kDa. No predicted signal peptide was observed, suggesting this enzyme to be localized within the cytoplasm of the cell. Homology studies of the deduced amino acid sequence in the area of its active sites classified the enzyme as a member of the α-amylase (AmyAC) superfamily of glycosyl hydrolases (GH), family 13 (GH13), subfamily 31 (GH13_31). malL was cloned in Escherichia coli and the coded enzyme overexpressed as a histidine-tagged protein (MalLHis). It was then purified and characterized. MalLHis protein showed strong hydrolytic activity towards 4-nitrophenyl-α-d-glucopyranoside (pNP-α-Glu) but not to other pNP-α-d- or pNP-β-d-derivatives. When using pNP-α-Glu as a substrate, MalLHis showed similar specific activities between pH5.0 and 6.0, and between 20 and 42°C (optimum 30°C). Among the natural carbohydrates assayed, MalLHis showed specificity towards isomaltose (V max and K m values of 40.64μmolmin−1 mg−1 and 6.22mM) and much less to isomaltulose (V max and K m values of 168.86μmolmin−1 mg−1 and 244.52mM). However, under the conditions of the assay, the enzyme showed no transglycosylation activity. Characterization of the entire complement of glycosidases in L. plantarum might reveal how strains of this species could be used in new biotechnological applications or in the development of functional foods.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.021
      Issue No: Vol. 246 (2017)
       
  • Hypoxia and iron requirements are the main drivers in transcriptional
           adaptation of Kluyveromyces lactis during wine aerobic fermentation
    • Authors: Jordi Tronchoni; Alda J. Rodrigues; Jose Antonio Curiel; Pilar Morales; Ramon Gonzalez
      Pages: 40 - 49
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Jordi Tronchoni, Alda J. Rodrigues, Jose Antonio Curiel, Pilar Morales, Ramon Gonzalez
      The respiratory metabolism of yeast species alternative to Saccharomyces cerevisiae has been explored in recent years as a tool to reduce ethanol content in grape wine. The efficacy of this strategy has been previously proven for mixed cultures of non-Saccharomyces and S. cerevisiae strains. In this work, we perform a transcriptomic analysis of the Crabtree-negative yeast Kluyveromyces lactis under tightly controlled growth conditions in order to better understand physiology of non-Saccharomyces yeasts during the fermentation of grape must under aerated conditions. Transcriptional changes in K. lactis are mainly driven by oxygen limitation, iron requirement, and oxidative stress. Oxidative stress appears as a consequence of the hypoxic conditions achieved by K. lactis once oxygen supply is no longer sufficient to sustain fully respiratory metabolism. This species copes with low oxygen and iron availability by repressing iron consuming pathways and activating iron transport mechanisms. Most of the physiological and transcriptomic features of K. lactis in aerobic wine fermentation are not shared with the Crabtree-positive yeast S. cerevisiae.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.014
      Issue No: Vol. 246 (2017)
       
  • Assessing the capacity of growth, survival, and acid adaptive response of
           Listeria monocytogenes during storage of various cheeses and subsequent
           simulated gastric digestion
    • Authors: Anastasia E. Kapetanakou; Maria A. Gkerekou; Eirini S. Vitzilaiou; Panagiotis N. Skandamis
      Pages: 50 - 63
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Anastasia E. Kapetanakou, Maria A. Gkerekou, Eirini S. Vitzilaiou, Panagiotis N. Skandamis
      Different physicochemical and microbiological characteristics of cheeses may affect Listeria monocytogenes potential to grow, survive, or exhibit an acid adaptive response during storage and digestion. The objectives of the present study were to assess: i) the survival or growth potential of L. monocytogenes on various cheeses during storage, ii) the effect of initial indigenous microbiota on pathogen growth in comparison to expected growth curves retrieved by existing predictive models, and iii) the impact of habituation on/in cheeses surfaces on the subsequent acid resistance during simulated gastric digestion. Portions of cream (Cottage and Mascarpone), soft (Anthotyros, Camembert, Mastelo®, Manouri, Mozzarella, Ricotta), and semi-hard (Edam, Halloumi, Gouda) cheeses were inoculated with ca. 100CFU/g or cm2 of L. monocytogenes and stored under vacuum or aerobic conditions at 7°C (n =4). The impact of varying (initial) levels of starter culture or indigenous spoilage microbiota on pathogen growth was evaluated by purchasing cheese packages on different dates in relation to production and expiration date (subsequently reflecting to different batches) mimicking a potential situation of cheese contamination with L. monocytogenes during retail display. Values of pH and aw were also monitored and used to simulate growth of L. monocytogenes by existing models and compare it with the observed data of the study. Survival in simulated gastric fluid (SGF) (pH1.5; HCl; max. 120min) was assessed at three time points during storage. Mascarpone, Ricotta, Mozzarella, Camembert, and Halloumi supported L. monocytogenes growth by 0.5–0.8logCFU/g or cm2 per day, since low initial levels of total viable counts (TVC) (1.8–3.8logCFU/g or cm2) and high pH/aw values (ca. 6.23–6.64/0.965–0.993) were recorded. On Cottage, Anthotyros, Manouri, Mastelo®, Edam, and Gouda, the pathogen survived at populations similar or lower than the inoculation level due to the high reported competition and/or low pH/aw during storage. L. monocytogenes growth was significantly suppressed (p <0.05) on samples purchased close to expiration date (bearing high TVC), compared to those close to production date, regardless of cheese. Cheeses which supported growth of L. monocytogenes enabled higher survival in gastric acidity along their shelf-life compared to cheeses which did not support growth. However, even in the latter cheeses (i.e., Cottage, Mastelo®, Gouda), total elimination of a persisting low initial contamination was not always achieved. Such findings may provide useful evidence for assessing the risk posed by various cheeses types in relation to their compliance with food safety regulations.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.015
      Issue No: Vol. 246 (2017)
       
  • The efficacy of different cleaning and disinfection procedures to reduce
           Salmonella and Enterobacteriaceae in the lairage environment of a pig
           abattoir
    • Authors: Kavita Walia; Hector Argüello; Helen Lynch; Jim Grant; Finola C. Leonard; Peadar G. Lawlor; Gillian E. Gardiner; Geraldine Duffy
      Pages: 64 - 71
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Kavita Walia, Hector Argüello, Helen Lynch, Jim Grant, Finola C. Leonard, Peadar G. Lawlor, Gillian E. Gardiner, Geraldine Duffy
      This study investigated several cleaning and disinfection protocols for their ability to eliminate Salmonella and to reduce levels of Enterobacteriaceae, within the lairage pens of a commercial pig abattoir. Eight protocols were evaluated in each of 12 lairage pens at the end of the slaughtering day on 3 occasions (36 pens/protocol): (P1) high-pressure cold water wash (herein referred to as high-pressure wash); (P2) high-pressure wash followed by a quaternary ammonium compound (QAC)-based disinfectant without rinsing; (P3) high-pressure wash followed by a chlorocresol-based disinfectant without rinsing; (P4) high-pressure wash followed by a sodium hydroxide/sodium hypochlorite detergent with rinsing; (P5) P4 followed by P2; (P6) P4 followed by P3; (P7) P5 with drying for 24–48h; and (P8) P6 with drying for 24–48h. Two floor swabs and one wall swab were taken from each lairage pen before and after each protocol was applied, and examined for the presence of Salmonella and enumeration of Enterobacteriaceae. High-pressure washing alone (P1) did not reduce the prevalence of Salmonella in the lairage pens. When high-pressure washing, the probability of detecting Salmonella following application of the chlorocresol-based disinfectant (P3) was lower than with the QAC-based disinfectant, P2 (14.2% versus 34.0%, respectively; p<0.05). The probability of detecting Salmonella after the combined use of detergent and the chlorocresol-based disinfectant (P6) was also lower than application of detergent followed by the QAC-based disinfectant, P5 (2.2% versus 17.1%, respectively; p<0.05). Drying of pens (P7 and P8) greatly reduced the probability of detecting Salmonella. Only 3.8% of swabs were Salmonella-positive 48h after cleaning with detergent and the QAC-based disinfectant (P7); while an eradication of Salmonella was achieved 24h after cleaning with detergent and the chlorocresol-based disinfectant, P8. A reduction in Enterobacteriaceae counts to below the limit of detection (LOD; 10CFU/cm2) was achieved following cleaning with detergent and disinfection with the chlorocresol-based disinfectant, regardless of drying (p<0.05), whereas, applying detergent and the QAC-based disinfectant (P7) did not reduce Enterobacteriaceae counts to below the LOD. Therefore ensuring that lairage pens are allowed to dry after intensive cleaning with detergent and a chlorocresol-based disinfectant is recommended as the most effective hygiene routine to eliminate Salmonella and reduce Enterobacteriaceae counts.

      PubDate: 2017-02-12T07:27:04Z
      DOI: 10.1016/j.ijfoodmicro.2017.02.002
      Issue No: Vol. 246 (2017)
       
  • Efficacy of fungal and bacterial antagonists for controlling growth, FUM1
           gene expression and fumonisin B1 production by Fusarium verticillioides on
           maize cobs of different ripening stages
    • Authors: Nik Iskandar Putra Samsudin; Alicia Rodriguez; Angel Medina; Naresh Magan
      Pages: 72 - 79
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): Nik Iskandar Putra Samsudin, Alicia Rodriguez, Angel Medina, Naresh Magan
      This study was carried out to examine the efficacy of two biocontrol agents (Clonostachys rosea 016, BCA1; Gram-negative bacterium, BCA5) for control of FUM1 gene expression and fumonisin B1 (FB1) production by F. verticillioides FV1 on maize cobs of different ripening stages: R3, Milk (0.985 a w); R4, Dough (0.976 a w); R5, Dent (0.958 a w). Initially, temporal studies on FUM1 gene expression and FB1 production were performed on maize kernels for up to 14days. This revealed that day 10 was optimum for both parameters, and was used in the biocontrol studies. Maize cobs were inoculated with 50:50 mixtures of the pathogen:antagonist inoculum and incubated in environmental chambers to maintain the natural a w conditions for ten days at 25 and 30°C. The growth rates of F. verticillioides FV1, the relative expression of the FUM1 gene and FB1 production were quantified. It was found that, a w ×temp had significant impacts on growth, FUM1 gene expression and FB1 production by F. verticillioides FV1 on maize cobs of different maturities. The fungal antagonist (BCA1) significantly reduced FB1 contamination on maize cobs by >70% at 25°C, and almost 60% at 30°C regardless of maize ripening stage. For the bacterial antagonist (BCA5) however, FB1 levels on maize cobs were significantly decreased only in some treatments. These results suggest that efficacy of antagonists to control mycotoxin production in ripening maize cobs needs to take account of the ecophysiology of the pathogen and the antagonists, as well as the physiological status of the maize during silking to ensure effective control.

      PubDate: 2017-02-17T07:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.02.004
      Issue No: Vol. 246 (2017)
       
  • Continuous ohmic heating of commercially processed apple juice using five
           sequential electric fields results in rapid inactivation of
           Alicyclobacillus acidoterrestris spores
    • Authors: N.H. Kim; J.H. Ryang; B.S. Lee; C.T. Kim; M.S. Rhee
      Pages: 80 - 84
      Abstract: Publication date: 4 April 2017
      Source:International Journal of Food Microbiology, Volume 246
      Author(s): N.H. Kim, J.H. Ryang, B.S. Lee, C.T. Kim, M.S. Rhee
      Spores of Alicyclobacillus acidoterrestris, a spoilage bacterium, cause problems for the apple juice industry because they are resistant to thermal treatment. Here, we examined the sporicidal effect of an ohmic heating (OH) system with five sequential electric fields and compared it with that of conventional heating. Apple juice product (50kg) inoculated with A. acidoterrestris spores were subjected to OH (electric field strength=26.7V/cm; frequency=25kHz) at 85–100°C for 30–90s. The effect of conventional heating was also examined under these conditions. OH treatment at 100°C for 30s resulted in total inactivation of the inoculum, with no recovery of viable cells (initial population=4.8–4.9logCFU/ml), whereas 3.6–4.9logCFU/ml of the spores survived conventional heating. OH did not alter the quality (°Brix, color, and pH) of commercial apple juice (p >0.05). These results suggest that the OH system is superior to conventional heating for rapid sterilization (30s) of apple juice to assure microbiological quality in the absence of chemical additives.

      PubDate: 2017-02-17T07:32:27Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.002
      Issue No: Vol. 246 (2017)
       
  • A novel aptasensor for the colorimetric detection of S. typhimurium based
           on gold nanoparticles
    • Authors: Xiaoyuan Ma; Liangjing Song; Nixin Zhou; Yu Xia; Zhouping Wang
      Pages: 1 - 5
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Xiaoyuan Ma, Liangjing Song, Nixin Zhou, Yu Xia, Zhouping Wang
      A simple, fast and convenient colorimetric aptasensor was fabricated for the detection of Salmonella typhimurium (S. typhimurium) which was based on the color change effect of gold nanoparticles (GNPs). S. typhimurium is one of the most common causes of food-associated disease. Aptamers with specific recognition toward S. typhimurium was modified to the surface of prepared GNPs. They play a role for the protection of GNPs from aggregation toward high concentrations of NaCl. With the addition of S. typhimurium, aptamers preferably combined to S. typhimurium and the protection effect was broken. With more S. typhimurium, more aptamers detached from GNPs. In such a situation, the exposed GNPs would aggregated to some extent with the addition of NaCl. The color changed from red, purple to blue which could be characterized by UV–Vis spectrophotometer. The absorbance spectra of GNPs redshifted constantly and the intensity ratio of A700/A521 changed regularly. This could be calculated for the basis of quantitative detection of S. typhimurium from 102 cfu/mL to 107 cfu/mL. The obtained linear correlation equation was y=0.1946x–0.2800 (R2 =0.9939) with a detection limit as low as 56cfu/mL. This method is simple and rapid, results in high sensitivity and specificity, and can be used to detect actual samples.

      PubDate: 2017-01-23T02:51:10Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.024
      Issue No: Vol. 245 (2017)
       
  • Occurrence of Arcobacter spp. and correlation with the bacterial indicator
           of faecal contamination Escherichia coli in bivalve molluscs from the
           Central Adriatic, Italy
    • Authors: Francesca Leoni; Serena Chierichetti; Sabrina Santarelli; Giulia Talevi; Laura Masini; Chiara Bartolini; Elena Rocchegiani; M. Naceur Haouet; Donatella Ottaviani
      Pages: 6 - 12
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Francesca Leoni, Serena Chierichetti, Sabrina Santarelli, Giulia Talevi, Laura Masini, Chiara Bartolini, Elena Rocchegiani, M. Naceur Haouet, Donatella Ottaviani
      A total of 162 samples of bivalve molluscs (45 mussels and 117 clams) collected between December 2012 and 2014 from harvesting areas of the Central Adriatic were analysed by a culturing method for the presence of Arcobacter spp. Species identification was performed by PCR and sequencing analysis of a fragment of the rpoB gene. Overall, Arcobacter species were detected in 30% of samples, specifically 33% clams and 22% mussels. A. butzleri was the most common species (20% of the samples), followed by A. cryaerophilus (9%) and A. skirrowii (1%). A seasonal association of A. butzleri contamination was detected. A. butzleri was significantly more commonly recovered from samples collected during the winter-spring period (29%) than from those of the summer-autumn (8%). A. cryaerophilus was cultured from 6% to 11% of the samples collected in summer-autumn and winter-spring, respectively, but these differences were not statistically significant. A. skirrowii was recovered from a sample of mussels harvested in May 2014. To identify associations between the occurrence of Arcobacter spp. and E. coli levels, samples were divided into groups generating results with E. coli at >230MPN/100g and E. coli at ≤230MPN/100g, the latter corresponding to EU microbiological criteria allowed for live bivalve molluscs at retail level. A. butzleri was significantly more commonly detected in samples with higher E. coli levels (48%) than in those with lower levels of E. coli (10%), providing evidence for considering E. coli as an index organism for A. butzleri contamination in bivalve molluscs.

      PubDate: 2017-01-23T02:51:10Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.006
      Issue No: Vol. 245 (2017)
       
  • Validation of test portion pooling for Salmonella spp. detection in foods
    • Authors: David Tomás Fornés; Wendy McMahon; Julie Moulin; Adrianne Klijn
      Pages: 13 - 21
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): David Tomás Fornés, Wendy McMahon, Julie Moulin, Adrianne Klijn
      Pathogen monitoring programs play a crucial role in the verification of the effectiveness of implemented hygiene control measures. Sampling and testing procedures included in pathogen monitoring involve the analysis of multiple test portions where all samples must be negative for the presence of pathogens for a certain test portion size. Many food safety programs require increased testing due to the risks that a pathogen may be present. Analyzing more than one test portion could prove to be expensive and labor intensive. When more than one test portion for a specified food item is to be tested, the test portions could be combined to form a pooled test portion to reduce laboratory workload, costs of reagents and further confirmatory steps, but only when evidence is available that pooling does not affect on the number of false negative results for different matrices. This study has been performed to demonstrate the equivalence of test portion pooling for Salmonella detection with five different methods using cultural, ELISA and Real Time PCR technologies. Twenty-three (23) different food items including confectionary products, meal components, infant formula, pet food and powdered beverages were validated. Other complementary parameters like impact of minimum and maximum incubation time for pre-enrichment, temperature profile, pH and Salmonella concentration after the pre-enrichment and background flora have also been considered in the study. The results showed that pooling test portions up to 375g for Salmonella detection is valid for the methods that were tested. Relative level of detection (RLOD50) values for 22 of the food items tested were acceptable (i.e. lower than 2.5) when comparing the reference sample size (25g) against the alternative pooled sample size (375g), provided the enrichment broth was pre-warmed and maximum incubation time is respected.

      PubDate: 2017-01-23T02:51:10Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.005
      Issue No: Vol. 245 (2017)
       
  • Atmospheric pressure plasma jet treatment of Salmonella Enteritidis
           inoculated eggshells
    • Authors: Maike Moritz; Claudia Wiacek; Martin Koethe; Peggy G. Braun
      Pages: 22 - 28
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Maike Moritz, Claudia Wiacek, Martin Koethe, Peggy G. Braun
      Contamination of eggshells with Salmonella Enteritidis remains a food safety concern. In many cases human salmonellosis within the EU can be traced back to raw or undercooked eggs and egg products. Atmospheric pressure plasma is a novel decontamination method that can reduce a wide range of pathogens. The aim of this work was to evaluate the possibility of using an effective short time cold plasma treatment to inactivate Salmonella Enteritidis on the eggshell. Therefore, artificially contaminated eggshells were treated with an atmospheric pressure plasma jet under different experimental settings with various exposure times (15–300s), distances from the plasma jet nozzle to the eggshell surface (5, 8 or 12mm), feed gas compositions (Ar, Ar with 0.2, 0.5 or 1.0% O2), gas flow rates (5 and 7slm) and different inoculations of Salmonella Enteritidis (101–106 CFU/cm2). Atmospheric pressure plasma could reduce Salmonella Enteritidis on eggshells significantly. Reduction factors ranged between 0.22 and 2.27 log CFU (colony-forming units). Exposure time and, particularly at 104 CFU/cm2 inoculation, feed gas had a major impact on Salmonella reduction. Precisely, longer exposure times led to higher reductions and Ar as feed gas was more effective than ArO2 mixtures.

      PubDate: 2017-01-23T02:51:10Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.004
      Issue No: Vol. 245 (2017)
       
  • Estimating correlation of prevalence at two locations in the farm-to-table
           continuum using qualitative test data
    • Authors: Michael S. Williams; Eric D. Ebel
      Pages: 29 - 37
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Michael S. Williams, Eric D. Ebel
      The presence or absence of contaminants in food samples changes as a commodity moves along the farm-to-table continuum. Interest lies in the degree to which the prevalence (i.e., infected animals or contaminated sample units) at one location in the continuum, as measured by the proportion of test-positive samples, is correlated with the prevalence at a location later in the continuum. If prevalence of a contaminant at one location in the continuum is strongly correlated with the prevalence of the contaminant later in the continuum, then the effect of changes in contamination on overall food safety can be better understood. Pearson's correlation coefficient is one of the simplest metrics of association between two measurements of prevalence but it is biased when data consisting of presence/absence testing results are used to directly estimate the correlation. This study demonstrates the potential magnitude of this bias and explores the utility of three methods for unbiased estimation of the degree of correlation in prevalence. An example, based on testing broiler chicken carcasses for Salmonella at re-hang and post-chill, is used to demonstrate the methods.

      PubDate: 2017-01-23T02:51:10Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.007
      Issue No: Vol. 245 (2017)
       
  • Stevia-based sweeteners as a promising alternative to table sugar: The
           effect on Listeria monocytogenes and Salmonella Typhimurium growth
           dynamics
    • Authors: María M. Lobete; Maria Baka; Estefanía Noriega; Etienne Jooken; Annick Monballiu; Sam de Beurme; Boudewijn Meesschaert; Jan F. Van Impe
      Pages: 38 - 52
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): María M. Lobete, Maria Baka, Estefanía Noriega, Etienne Jooken, Annick Monballiu, Sam de Beurme, Boudewijn Meesschaert, Jan F. Van Impe
      Sugar is commonly substituted with stevia-based products in food industry and in our daily-life. This substitution results in a change in food product characteristic formula and properties that may affect the growth dynamics of food pathogenic and spoilage bacteria. This work studies the effect of table sugar (TS), laboratory sucrose (LS), commercial stevia (St) and steviol glycosides (SG) on the growth dynamics of Salmonella Typhimurium and Listeria monocytogenes. Experiments were carried out in general and minimal culture media at 3 equivalent concentration levels in terms of sweetness intensity (TS and LS at 3, 9 and 15% (w/v); St at 0.3, 0.9 and 1.5% (w/v); and SG at 0.01, 0.03 and 0.05% (w/v)). Incubation temperatures were: 4, 8 and 20°C for general media, and for minimal media 20°C. To decipher the role of these sweeteners, their concentration evolution in minimal media was determined via HPLC analysis. The results revealed slow maximum specific growth rates (μ max ) of S. Typhimurium in general media with increasing concentrations of TS and LS at 20°C; and reduced maximum cell population (N max ) at 8°C. The growth of L. monocytogenes in general culture media remains invariable independently of the sweetener added, except at 4°C. At this critical temperature, the presence of TS, LS and St seems to facilitate the growth of L. monocytogenes, presenting higher μ max values in comparison to SG and the control. Varying bacterial response to changes in media formulation suggests that further research is required, focusing on revealing the microbial dynamics in structured media, as well as in real food products.

      PubDate: 2017-01-30T04:54:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.008
      Issue No: Vol. 245 (2017)
       
  • Genetic and serological identification of three Vibrio parahaemolyticus
           strains as candidates for novel provisional O serotypes
    • Authors: Xi Guo; Bin Liu; Min Chen; Yuanyuan Wang; Lu Wang; Hongyou Chen; Yao Wang; Lihong Tu; Xi Zhang; Lu Feng
      Pages: 53 - 58
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Xi Guo, Bin Liu, Min Chen, Yuanyuan Wang, Lu Wang, Hongyou Chen, Yao Wang, Lihong Tu, Xi Zhang, Lu Feng
      Vibrio parahaemolyticus is a Gram-negative, halophilic Vibrio that naturally inhabits marine and estuarine environments worldwide and has recently been recognized as one of the most important foodborne pathogens. To date, 13 O serotypes and 71 K serotypes of V. parahaemolyticus have been identified. However, untypeable V. parahaemolyticus strains are frequently found during routine detection, indicating that other forms of serotypes exist and suggesting the necessity for extension of the antigenic scheme. In this work, through the genetic analysis of the O serotype genetic determinants (OGDs) and the production of antisera and serological tests, we identified three novel O serotypes of V. parahaemolyticus. Further analyses showed that recombination and gene-set deletions/insertions within OGDs may play key roles in the generation of V. parahaemolyticus O serotype diversity. A PCR method was developed for the identification of these novel O serotypes, and specificity and sensitivity were evaluated. A double-blind test including 283 clinical isolates was performed, giving perfect correlation with the agglutination test results. Generally, our study expanded the O-antigenic scheme of V. parahaemolyticus from 13 to 16 and provided a tool with the potential for the detection and identification of V. parahaemolyticus strains (especially untypeable strains) isolated from both the clinic and the environment.

      PubDate: 2017-01-30T04:54:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.010
      Issue No: Vol. 245 (2017)
       
  • The Antarctic yeast Candida sake: Understanding cold metabolism impact on
           wine
    • Authors: Lidia Ballester-Tomás; Jose A. Prieto; Jose V. Gil; Marcelo Baeza; Francisca Randez-Gil
      Pages: 59 - 65
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Lidia Ballester-Tomás, Jose A. Prieto, Jose V. Gil, Marcelo Baeza, Francisca Randez-Gil
      Current winemaking trends include low-temperature fermentations and using non-Saccharomyces yeasts as the most promising tools to produce lower alcohol and increased aromatic complexity wines. Here we explored the oenological attributes of a C. sake strain, H14Cs, isolated in the sub-Antarctic region. As expected, the cold sea water yeast strain showed greater cold growth, Na+-toxicity resistance and freeze tolerance than the S. cerevisiae QA23 strain, which we used as a commercial wine yeast control. C. sake H14Cs was found to be more sensitive to ethanol. The fermentation trials of low-sugar content must demonstrated that C. sake H14Cs allowed the cold-induced lag phase of growth to be eliminated and also notably reduced the ethanol (−30%) and glycerol (−50%) content in wine. Instead C. sake produced sorbitol as a compatible osmolyte. Finally, the inspection of the main wine volatile compounds revealed that C. sake produced more higher alcohols than S. cerevisiae. In conclusion, our work evidences that using the Antarctic C. sake H14Cs yeast improves low-temperature must fermentations and has the potential to provide a wine with less ethanol and also particular attributes.

      PubDate: 2017-01-30T04:54:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.009
      Issue No: Vol. 245 (2017)
       
  • Spread of ESBL/AmpC-producing Escherichia coli and Klebsiella pneumoniae
           in the community through ready-to-eat sandwiches in Algeria
    • Authors: Lydia Yaici; Marisa Haenni; Véronique Métayer; Estelle Saras; Ferielle Mesbah Zekar; Meriem Ayad; Abdelaziz Touati; Jean-Yves Madec
      Pages: 66 - 72
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Lydia Yaici, Marisa Haenni, Véronique Métayer, Estelle Saras, Ferielle Mesbah Zekar, Meriem Ayad, Abdelaziz Touati, Jean-Yves Madec
      The spread of Extended-Spectrum β-Lactamases (ESBLs) or AmpC β-Lactamases (AmpC) encoding genes in healthy human populations is of major concern. The role of the food chain has been questioned since numerous studies reported surface contamination of retail meat or crude vegetables with ESBL/AmpC-producing Enterobacteriaceae (ESBL/AmpC-E). Nonetheless, these food products are intended to be cooked or washed before consumption so that the risk of human transfer might be low. Here, the presence of ESBL/AmpC-E was investigated in ready-to-eat (RTE) sandwiches purchased in the street in the city of Bejaia, Algeria. Thirty ESBL/AmpC-producing E. coli (n=18), K. pneumoniae (n=11) and K. oxytoca (n=1) were recovered from 21 sandwiches purchased in 14 of the 100 shops that were visited (14%). Twenty-four isolates (13 E. coli, 10 K. pneumoniae, 1 K. oxytoca) produced one or two ESBLs, while 5 E. coli and 1 K. pneumoniae isolates produced an AmpC. Among those, 12 E. coli harbored bla CTX-M-1 (n=7), bla CTX-M-15 (n=3), bla CTX-M-14 (n=1) or bla CTX-M-2 (n=1) and one E. coli co-harbored the bla CTX-M-15 and bla SHV-2 genes. The 10 K. pneumoniae displayed bla CTX-M-15 (n=7), bla SHV-2 (n=3), bla SHV-12 (n=1) or bla CTX-M-1 (n=1), including two isolates presenting a bla CTX-M-15 /bla SHV-2 or bla CTX-M-1 /bla SHV-2 combination. The K. oxytoca harbored the bla SHV-2 gene, and one K. pneumoniae and four E. coli displayed bla DHA and bla CMY-2, respectively. Most isolates (26/30, n=87%) also possessed the aac(6′)-Ib-cr gene. Identical ESBL/AmpC-producing E. coli or K. pneumoniae clones were detected at different places across the city. This may reflect cross-contamination through poor handling practices, contaminated equipment, common ingredients or environmental factors. Of note, the emergent ST405 K. pneumoniae human clone was identified as a CTX-M-15 producer. This study highlights the presence of ESBL/AmpC-E in RTE sandwiches, which are a source of direct transfer to the human gut. These data indicate that fast food shops should be regarded as ESBL/AmpC reservoirs, and a risk for humans. Major efforts should be made in Algeria through guidelines on good practices in the food chain, and more globally in all countries sharing similar poor levels of food hygiene worldwide.

      PubDate: 2017-01-30T04:54:16Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.011
      Issue No: Vol. 245 (2017)
       
  • Diversity and persistence of Listeria monocytogenes within the Gorgonzola
           PDO production chain and comparison with clinical isolates from the same
           area
    • Authors: Virginia Filipello; Silvia Gallina; Ettore Amato; Marina Nadia Losio; Mirella Pontello; Lucia Decastelli; Sara Lomonaco
      Pages: 73 - 78
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Virginia Filipello, Silvia Gallina, Ettore Amato, Marina Nadia Losio, Mirella Pontello, Lucia Decastelli, Sara Lomonaco
      Listeria monocytogenes causes invasive syndromes with high fatality rates in specific population groups. Cheeses have been commonly implicated in outbreaks worldwide. Gorgonzola is a cheese only produced in Northwestern Italy (it is the third Italian cheese in terms of production and export) and L. monocytogenes is frequently isolated from the production chain. The aims of this study were to assess the distribution of L. monocytogenes Virulence Types (VTs) in isolates collected in Gorgonzola processing plants and to determine the presence of Epidemic Clones (ECs). Fifty-Six L. monocytogenes strains collected between 2004 and 2016 from cheese and environmental samples were subtyped with Multi-Virulence-Locus Sequence Typing (MVLST) and compared to previously typed strains. Most isolates (n =50) belonged to two new VTs (VT113 and VT114). The remaining isolates belonged to previously identified VTs: VT14-ECVIII (milk chocolate outbreak, 1994, USA) and VT80 (ricotta salata outbreak, 2012, USA). VT14, VT80 and VT113 were shared with isolates from apparently sporadic human cases in the same geographical area and temporal period (Piedmont and Lombardy, 2005–2016). The overall L. monocytogenes population appears to be homogeneous and may be characteristic of Gorgonzola production. Nevertheless, the detection in cheese and environmental samples of VTs observed in clinical isolates or outbreak related strains (VT80, VT14) contributed to better describe the current scenario and pointed out the need for increased surveillance.

      PubDate: 2017-02-06T01:30:06Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.012
      Issue No: Vol. 245 (2017)
       
  • Survival of Listeria monocytogenes with different antibiotic resistance
           patterns to food-associated stresses
    • Authors: Norton Komora; Carolina Bruschi; Rui Magalhães; Vânia Ferreira; Paula Teixeira
      Pages: 79 - 87
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Norton Komora, Carolina Bruschi, Rui Magalhães, Vânia Ferreira, Paula Teixeira
      The ongoing rise of antibiotic resistant microbial pathogens has become one of the major public health threats worldwide. Despite all the effort and actions taken so far, a proliferation of antibiotic resistant (AR) and multi-antibiotic resistant (MAR) strains is still observed, including in foodborne pathogens. This trend has been also noted recently for isolates of Listeria monocytogenes, a species that, although remaining largely sensitive to clinically relevant antimicrobials, has been reported to develop increased tolerance to antibiotics, particularly in isolates recovered from the food-chain. In this study we compared the ability of MAR (n =8), AR (n =18) and antibiotic susceptible (AS, n =11) L. monocytogenes strains from food and clinical origin to survive to different environmental stress conditions, including temperature (58°C), acidic stress (1% v/v lactic acid, pH3.5), and osmotic stress (37% w/v NaCl). The presence of antibiotic active efflux among MAR and AR strains, and its role on L. monocytogenes tolerance to different antimicrobial compounds was also investigated, namely; hydrogen peroxide; organic acids (acetic, citric and lactic); nisin; benzalkonium chloride (BC); and, sodium nitrite. While no significant differences were observed in the survival of the 37 strains exposed to high temperature (58°C), overall the mean logarithmic reduction of clinical strains was statistically lower after acid and salt exposure than that observed for strains of food origin; but both food and clinical strains resistant to two or three antibiotics were significantly less susceptible to acid (lactic acid 1% v/v) and osmotic stresses (37% w/v NaCl) when compared to AS strains. Using the EtBr-agar Cartwheel method, it was possible to detect efflux pumps in three of the 26 MAR and AR isolates, including one control strain; the active efflux in theses isolates was proven to be associated with fluoroquinolone resistance, and possible extrusion of BC and hydrogen peroxide. The mechanisms responsible for the possible correlation between resistance to antibiotics and to acid or salt stress in L. monocytogenes have yet to be understood.

      PubDate: 2017-02-06T01:30:06Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.013
      Issue No: Vol. 245 (2017)
       
  • Phenylalanine and urea foliar application: Effect on grape and must
           microbiota
    • Authors: Lucía González-Arenzana; Javier Portu; Rosa López; Patrocinio Garijo; Teresa Garde-Cerdán; Isabel López-Alfaro
      Pages: 88 - 97
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Lucía González-Arenzana, Javier Portu, Rosa López, Patrocinio Garijo, Teresa Garde-Cerdán, Isabel López-Alfaro
      The main aim of this study was to describe the impact of foliar phenylalanine and urea application on grape and must microbial populations. The tool used to perform the ecological study was DGGE conducted with several infusions in non-enriched and enriched liquid media, as well as direct DNA extractions of grapes and musts. A total of 75 microbial species were found in the study. The alpha diversity indices of grape after both foliar nitrogen treatments did not show significant changes in comparison to the control samples, but were modified in some indices in must samples. The phenylalanine must sample was similar to the control, while foliar urea application caused significant changes in microbial diversity and population structure in comparison to the control must. Further research would be necessary to properly predict the impact on winemaking of the effects observed in this study for grape and must microbiota, especially regarding the foliar application of urea.

      PubDate: 2017-02-06T01:30:06Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.017
      Issue No: Vol. 245 (2017)
       
  • Multi-locus sequence typing of Laribacter hongkongensis isolates from
           freshwater animals, environment and diarrhea patients in southern China
    • Authors: Zhiyun Wang; Jiangfeng Zhu; Zhihua Liu; Youzhao Liu; Nancai Zheng; Mei Feng; Qing Chen; Weijun Yu; Lina Jiang; Jing Hu
      Pages: 98 - 104
      Abstract: Publication date: 20 March 2017
      Source:International Journal of Food Microbiology, Volume 245
      Author(s): Zhiyun Wang, Jiangfeng Zhu, Zhihua Liu, Youzhao Liu, Nancai Zheng, Mei Feng, Qing Chen, Weijun Yu, Lina Jiang, Jing Hu
      Laribacter hongkongensis is a novel emerging bacterium associated with gastroenteritis and invasive bacteremic infections. Freshwater fish and edible frogs have been identified as major reservoirs of L. hongkongensis. Currently one of the main challenges in L. hongkongensis research is to identify their sources and possible transmission routes. The aim of this study was to determine the genetic diversity and relatedness of these L. hongkongensis isolates to their hosts in the hope of shedding light on these issues. In this study, multi-locus sequence typing (MLST) was used to determine the genetic characteristics of 114 L. hongkongensis strains, including 113 isolated from humans, fish, frogs, Amazonian snails and water sample in Guangzhou and Jiangmen, Southern China, and one reference isolate HZ242, recovered from a diarrhea patient in Hangzhou. The relationships among the STs and the relatedness among the isolates were assessed by phylogenetic and eBURST analysis. A total of 72 different sequence types (STs) from 114 isolates of L. hongkongensis were identified by MLST analysis, and ST99-ST161were novel. Significant difference of the prevalence of different STs between fish isolates (41.8%, 23/55) and frog isolates (82.4%, 42/51) was revealed (p=0.000). The most frequent ST (ST45) was identified 28 times and only found in fish isolates. In addition, 10 groups were identified by eBURST in this study. Combined the MLST data from Hong Kong and the present study, there were eight eBRUST lineages (group A-H) included the isolates (49.2%, 128/260) from either numerous hosts or multiple geographic origins, which contained 33.1% (53/160) of all the STs. Group A (n=57, STs=20) consisted exclusively of isolates from fish and 92.9% (39/42) of isolates in group B (n=42, STs=16) were only from fish. Group C-F (n=22, STs=14) were found to be associated with human, apart from other hosts. In this study, extensive genetic heterogeneity among the L. hongkongensis isolates from various hosts was observed. Specifically, there is higher genetic diversity of L. hongkongensis isolates of frog-origin than those of fish-origin. This study indicated some isolates exhibited a preference for specific hosts or geographic areas. ST45 was revealed to be the most frequent ST, which was only found in the fish isolates in Southern China, but might be irrelative to human infection. This MLST study further revealed that frog was likely to be another major source for human infection with L. hongkongensis apart from fish.

      PubDate: 2017-02-06T01:30:06Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.016
      Issue No: Vol. 245 (2017)
       
  • The response of growth and patulin production of postharvest pathogen
           Penicillium expansum to exogenous potassium phosphite treatment
    • Authors: Tongfei Lai; Ying Wang; Yaya Fan; Yingying Zhou; Ying Bao; Ting Zhou
      Pages: 1 - 10
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Tongfei Lai, Ying Wang, Yaya Fan, Yingying Zhou, Ying Bao, Ting Zhou
      In this study, the effects of exogenous potassium phosphite (Phi) on growth and patulin production of postharvest pathogen Penicillium expansum were assessed. The results indicated that P. expansum under 5mmol/L Phi stress presented obvious development retardation, yield reduction of patulin and lower infectivity to apple fruit. Meanwhile, expression analysis of 15 genes related to patulin biosynthesis suggested that Phi mainly affected the early steps of patulin synthetic route at transcriptional level. Furthermore, a global view of proteome and transcriptome alteration of P. expansum spores during 6h of Phi stress was evaluated by iTRAQ (isobaric tags for relative and absolute quantitation) and RNA-seq (RNA sequencing) approaches. A total of 582 differentially expressed proteins (DEPs) and 177 differentially expressed genes (DEGs) were acquired, most of which participated in carbohydrate metabolism, amino acid metabolism, lipid metabolism, genetic information processing and biosynthesis of secondary metabolites. Finally, 39 overlapped candidates were screened out through correlational analysis between iTRAQ and RNA-seq datasets. These findings will afford more precise and directional clues to explore the inhibitory mechanism of Phi on growth and patulin biosynthesis of P. expansum, and be beneficial to develop effective controlling approaches based on Phi.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.017
      Issue No: Vol. 244 (2017)
       
  • Lowering histamine formation in a red Ribera del Duero wine (Spain) by
           using an indigenous O. oeni strain as a malolactic starter
    • Authors: Carmen Berbegal; Yaiza Benavent-Gil; Eva Navascués; Almudena Calvo; Clara Albors; Isabel Pardo; Sergi Ferrer
      Pages: 11 - 18
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Carmen Berbegal, Yaiza Benavent-Gil, Eva Navascués, Almudena Calvo, Clara Albors, Isabel Pardo, Sergi Ferrer
      This study demonstrates for the first time that a non-commercial selected autochthonous O. oeni strain has been used to conduct malolactic fermentation (MLF) while lowering histamine formation in the same winery. Lactic acid bacteria (LAB) were isolated from 13 vats before and after spontaneous MLF at the Pago de Carraovejas winery from the Ribera del Duero region (Spain). Only O. oeni were present, typed and characterized, and both histamine producer and non-producers existed. From the non-producers, one strain was selected to become a starter according to its genetic profile, prevalence in the different wines in the winery, resistance to alcoholic degree, resistance to high polyphenolic content, inability to synthesise histamine, growth kinetics and malolactic activity. This starter was produced at semi-industrial levels to inoculate 20,000L of Tempranillo red wine. The inoculated vat showed 5-fold less histamine than the non-inoculated control vat. After 1year, the barrel-ageing histamine concentrations were 3-fold lower in the inoculated vat than in the non-inoculated vat.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.013
      Issue No: Vol. 244 (2017)
       
  • Endolysin LysSA97 is synergistic with carvacrol in controlling
           Staphylococcus aureus in foods
    • Authors: Yoonjee Chang; Hyunjin Yoon; Dong-Hyun Kang; Pahn-Shick Chang; Sangryeol Ryu
      Pages: 19 - 26
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Yoonjee Chang, Hyunjin Yoon, Dong-Hyun Kang, Pahn-Shick Chang, Sangryeol Ryu
      LysSA97 is an endolysin encoded by the bacteriophage SA97, the genome sequence of which has been recently revealed. LysSA97 has lytic activity against a variety of Staphylococcus strains that cause foodborne illness. In order to improve its potential as a biocontrol agent against Staphylococcus, various types of essential oil-derived active compounds were tested in combination with LysSA97; carvacrol exhibited significant synergistic effects when combined with LysSA97. The synergistic antimicrobial activity between endolysin and carvacrol in food products, including milk and beef, were investigated. While LysSA97 (376nM) and carvacrol (3.33mM) showed 0.8±0.2 and 1.0±0.0logCFU/mL reduction in Staphylococcus aureus cells, respectively; when applied alone in bacterial culture, the cocktail containing both at the same concentrations exhibited a bacterial decrease of 4.5±0.2logCFU/mL. The synergistic activity of carvacrol was also reproduced in combination with other endolysins, and their cooperative bactericidal effects were validated in ten additional S. aureus strains, including two methicillin-resistant S. aureus (MRSA), suggesting the wide application of carvacrol as a bactericidal agent coupled with endolysin. When LysSA97 and carvacrol were used in combination in foods, the synergistic activity appeared to be influenced by the total lipid content of foods, and bacteria in skim milk were more drastically inactivated than those in whole milk. Therefore, this is the first report demonstrating that endolysin and carvacrol act synergistically to inactivate S. aureus in food products.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.007
      Issue No: Vol. 244 (2017)
       
  • Source tracking of prokaryotic communities in fermented grain of Chinese
           strong-flavor liquor
    • Authors: Xueshan Wang; Hai Du; Yan Xu
      Pages: 27 - 35
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Xueshan Wang, Hai Du, Yan Xu
      The fermentation process of Chinese strong-flavor liquor involves numerous microbes originating from Daqu and pit mud. Daqu is the starter of fermentation, and pit mud acts as another source of inoculum of microbes in the liquor-making process. However, the contribution of microbes in pit mud and Daqu to fermented grain, and the sources of microbes in fermented grain are still waiting to be defined clearly. In this study, prokaryotic communities in fermented grain, pit mud and Daqu were identified via next generation sequencing of the V4 region of 16S rRNA gene. Principal-coordinate analysis indicated that Daqu had stronger influence on the prokaryotic communities in fermented grain at the prophase of fermentation, but pit mud influenced the fermented grain continuously during the whole fermentation process. Totally, 299 genera were detected in all fermented grain, pit mud and Daqu samples. Among them, 204 genera were detected in 3days' fermented grain. Ten genera (Lactobacillus, Leuconostoc, Staphylococcus, Gluconobacter, Acetobacter, Petrimonas, Clostridium, Ruminococcus, Methanobacterium and Methanobrevibacter) were dominant, and accounted for 84.31%–87.13% relative abundance of the total prokaryotic community in fermented grain. Venn analysis indicated Daqu was the main source of strict aerobes and facultative aerobes, which took up over 74% of prokaryotic communities in fermented grain. Conversely, pit mud was the sustained-release source of anaerobes, which accounted for over 14% of prokaryotic communities in fermented grain. In addition, part of anaerobes originated from both Daqu and pit mud. This study could help track the source of prokaryotic communities in fermented grain, and improve the quality and controllability in liquor production.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.018
      Issue No: Vol. 244 (2017)
       
  • Characterization of Fusarium graminearum isolates recovered from wheat
           samples from Argentina by Fourier transform infrared spectroscopy:
           Phenotypic diversity and detection of specific markers of aggressiveness
    • Authors: Cecilia B. Fígoli; Rodrigo Rojo; Laura A. Gasoni; Gisele Kikot; Mariana Leguizamón; Raúl R. Gamba; Alejandra Bosch; Teresa M. Alconada
      Pages: 36 - 42
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Cecilia B. Fígoli, Rodrigo Rojo, Laura A. Gasoni, Gisele Kikot, Mariana Leguizamón, Raúl R. Gamba, Alejandra Bosch, Teresa M. Alconada
      Fusarium graminearum is the primary causal agent of Fusarium head blight of wheat in Argentina. This disease affects crop yields and grain quality also reducing the wheat end-use, and causing mycotoxin contamination. The aim of this work was to analyze the phenotypic characteristics associated with phenotypic diversity and aggressiveness of 34 F. graminearum sensu stricto isolates recovered from Argentinean fields in the 2008 growing season using the Fourier Transform Infrared (FTIR) dried film technology. We applied this technique also to search for spectral specific markers associated with aggressiveness. The combination of FTIR technology with hierarchical cluster analysis allowed us to determine that this population constitutes a highly diverse and heterogeneous group of fungi with significant phenotypic variance. Still, when the spectral features of a set of these isolates were compared against their aggressiveness, as measured by disease severity, thousand grains weight, and relative yield reduction, we found that the more aggressive isolates were richer in lipid content. Therefore, we could define several spectroscopic markers (>CH stretching modes in the 3000–2800 window, >CO and CO vibrational modes of esters at 1765–1707cm−1 and 1474–900cm−1, respectively), mostly assigned to lipid content that could be associated with F. graminearum aggressiveness. All together, by the application of FTIR techniques and simple multivariate analyses, it was possible to gain significant insights into the phenotypic characterization of F. graminearum local isolates, and to establish the existence of a direct relationship between lipid content and fungal aggressiveness. Considering that lipids have a major role as mediators in the interaction between plants and fungi our results could represent an attractive outcome in the study of Fusarium pathogenesis.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.016
      Issue No: Vol. 244 (2017)
       
  • Quantitative assessment of viable cells of Lactobacillus plantarum strains
           in single, dual and multi-strain biofilms
    • Authors: Mónica D. Fernández Ramírez; Ioannis Kostopoulos; Eddy J. Smid; Masja N. Nierop Groot; Tjakko Abee
      Pages: 43 - 51
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Mónica D. Fernández Ramírez, Ioannis Kostopoulos, Eddy J. Smid, Masja N. Nierop Groot, Tjakko Abee
      Biofilms of Lactobacillus plantarum are a potential source for contamination and recontamination of food products. Although biofilms have been mostly studied using single species or even single strains, it is conceivable that in a range of environmental settings including food processing areas, biofilms are composed of multiple species with each species represented by multiple strains. In this study six spoilage related L. plantarum strains FBR1-FBR6 and the model strain L. plantarum WCFS1 were characterised in single, dual and multiple strain competition models. A quantitative PCR approach was used with added propidium monoazide (PMA) enabling quantification of intact cells in the biofilm, representing the viable cell fraction that determines the food spoilage risk. Our results show that the performance of individual strains in multi-strain cultures generally correlates with their performance in pure culture, and relative strain abundance in multi-strain biofilms positively correlated with the relative strain abundance in suspended (planktonic) cultures. Performance of individual strains in dual-strain biofilms was highly influenced by the presence of the secondary strain, and in most cases no correlation between the relative contributions of viable planktonic cells and viable cells in the biofilm was noted. The total biofilm quantified by CV staining of the dual and multi-strain biofilms formed was mainly correlated to CV values of the dominant strain obtained in single strain studies. However, the combination of strain FBR5 and strain WCFS1 showed significantly higher CV values compared to the individual performances of both strains indicating that total biofilm formation was higher in this specific condition. Notably, L. plantarum FBR5 was able to outgrow all other strains and showed the highest relative abundance in dual and multi-strain biofilms. All the dual and multi-strain biofilms contained a considerable number of viable cells, representing a potential source of contamination.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.014
      Issue No: Vol. 244 (2017)
       
  • Evaluation of Muscodor cinnamomi as an egg biofumigant for the reduction
           of microorganisms on eggshell surfaces and its effect on egg quality
    • Authors: Nakarin Suwannarach; Chariya Kaewyana; Arpaporn Yodmeeklin; Jaturong Kumla; Kenji Matsui; Saisamorn Lumyong
      Pages: 52 - 61
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Nakarin Suwannarach, Chariya Kaewyana, Arpaporn Yodmeeklin, Jaturong Kumla, Kenji Matsui, Saisamorn Lumyong
      The presence of microorganisms on the eggshell surface is a factor of consideration in determining egg quality. These microorganisms can contribute to egg spoilage and can infect the egg. In this study, 18 morphotypes of microorganisms were isolated from eggshells. Morphological, biochemical, physiological and molecular analyses were used to identify these morphotypes into 7 species; Bacillus drentensis, Staphylococcus arlettae, Stap. cohnii, Stap. kloosii, Stap. saprophyticus, Stap. sciuri and Stap. xylosus. The potential of Muscodor cinnamomi to reduce the presence of microorganisms on eggshells by biological fumigation was investigated. The result showed that 16 strains of the tested microorganisms were inactivated after the exposure of the fungal volatile organic compounds. The most abundant compound was 2-methylpropanoic acid, followed by 3-methylbutan-1-ol. Our results indicated that a 24-h period of fumigation of 100g rye grain culture of M. cinnamomi was the minimum dose that could significantly reduce the number of microorganisms on the eggshell surface. Fumigated eggs from both box and cabinet fumigation trials showed significantly lower microbial numbers on the eggshell than non-fumigated eggs during the storage period of 14days. It was found that the values of the yolk index, albumen index and the Haugh unit of the eggs decreased during this storage time. However, those values of the fumigated eggs from both fumigation trials were found to be significantly higher than the non-fumigated eggs after the 24-h fumigation period and following storage for 5, 7 and 14days. However, the values of the albumen index were not found to have significantly increased over 5days of the box trial. This study is the first to report on mycofumigation activity for the purposes of reducing the presence of microorganisms on the surface of eggshells.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.021
      Issue No: Vol. 244 (2017)
       
  • Impact of dry chilling on the genetic diversity of Escherichia coli on
           beef carcasses and on the survival of E. coli and E. coli O157
    • Authors: Jeyachchandran Visvalingam; Yang Liu; Xianqin Yang
      Pages: 62 - 66
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Jeyachchandran Visvalingam, Yang Liu, Xianqin Yang
      The objective of this study was to examine the effect of dry chilling on the genetic diversity of naturally occurring Escherichia coli on beef carcasses, and to examine whether two populations of E. coli recovered from carcasses during chilling and E. coli O157 differed in their response to desiccation. Isolates of E. coli were obtained from beef carcasses during a 67h dry chilling process and were genotyped using multiple-locus variable-number tandem-repeat analysis (MLVA). Ten E. coli genotypes found only at 0h (group A) and found more than once (group B), as well as five strains of E. coli O157 (group C) were inoculated on stainless steel coupons and their survival was examined after exposure to 75 and 100% relative humidity (RH) at 0 or 35°C for 67h. A total of 450 E. coli isolates were obtained, with 254, 49, 49, 51, 23, 20, and 4 from 0, 1, 2, 4, 6, 8 and 24h of chilling, respectively. No E. coli were recovered at 67h. MLVA of the isolates revealed 173 distinct genotypes. Genetic diversity of E. coli isolates, defined as ratio of the number of isolates to the number of genotypes, remained between 2.3 and 1.3 during the 24h of chilling. All strains inoculated on stainless steel coupons and exposed to 75% RH at 35°C were completely inactivated, irrespective of their groups. Inactivation of E. coli of the three groups was not significantly (P >0.05) different by exposure to 75% RH at 0°C. The findings indicate that the genetic diversity of E. coli on beef carcasses was not affected by dry chilling. In addition, inactivation of E. coli genotypes and E. coli O157 by desiccation on stainless steel simulating dry chilling conditions did not differ significantly (P >0.05). Thus, dry chilling may be used as an effective antimicrobial intervention for beef carcasses.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.022
      Issue No: Vol. 244 (2017)
       
  • Population analysis of biofilm yeasts during fino sherry wine aging in the
           Montilla-Moriles D.O. region
    • Authors: Miriam Marin-Menguiano; Sandra Romero-Sanchez; Ramón R. Barrales; Jose I. Ibeas
      Pages: 67 - 73
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Miriam Marin-Menguiano, Sandra Romero-Sanchez, Ramón R. Barrales, Jose I. Ibeas
      Fino is the most popular sherry wine produced in southern Spain. Fino is matured by biological aging under a yeast biofilm constituted of Saccharomyces cerevisiae yeasts. Although different S. cerevisiae strains can be identified in such biofilms, their diversity and contribution to wine character have been poorly studied. In this work, we analyse the flor yeast population in five different wineries from the Montilla-Moriles D.O. (Denominación de Origen) in southern Spain. Yeasts present in wines of different ages were identified using two different culture-dependent molecular techniques. From 2000 individual yeast isolates, five different strains were identified with one of them dominating in four out of the five wineries analysed, and representing 76% of all the yeast isolates collected. Surprisingly, this strain is similar to the predominant strain isolated twenty years ago in Jerez D.O. wines, suggesting that this yeast is particularly able to adapt to such a stressful environment. Fino wine produced with pure cultures of three of the isolated strains resulted in different levels of acetaldehyde. Because acetaldehyde levels are a distinctive characteristic of fino wines and an indicator of fino aging, the use of molecular techniques for yeast identification and management of yeast populations may be of interest for fino wine producers looking to control one of the main features of this wine.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.019
      Issue No: Vol. 244 (2017)
       
  • Impact of environmental factors on the culturability and viability of
           Listeria monocytogenes under conditions encountered in food processing
           plants
    • Authors: Anaïs Overney; Joséphine Jacques-André-Coquin; Patricia Ng; Brigitte Carpentier; Laurent Guillier; Olivier Firmesse
      Pages: 74 - 81
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Anaïs Overney, Joséphine Jacques-André-Coquin, Patricia Ng, Brigitte Carpentier, Laurent Guillier, Olivier Firmesse
      The ability of Listeria monocytogenes to adhere to and persist on surfaces for months or even years may be responsible for its transmission from contaminated surfaces to food products. Hence the necessity to find effective means to prevent the establishment of L. monocytogenes in food processing environments. The aim of this study was to assess, through a fractional experimental design, the environmental factors that could affect the survival of L. monocytogenes cells on surfaces to thereby prevent the persistence of this pathogen in conditions mimicking those encountered in food processing plants: culture with smoked salmon juice or meat exudate, use of two materials with different hygiene status, biofilm of L. monocytogenes in pure-culture or dual-culture with a Pseudomonas fluorescens strain, application of a drying step after cleaning and disinfection (C&D) and comparison of two strains of L. monocytogenes. Bacterial survival was assessed by culture, qPCR to quantify total cells, and propidium monoazide coupled with qPCR to quantify viable cells and highlight viable but non-culturable (VBNC) cells. Our results showed that failure to apply C&D causes cell persistence on surfaces. Moreover, the sanitation procedure leads only to a loss of culturability and appearance of VBNC populations. However, an additional daily drying step after C&D optimises the effectiveness of these procedures to reduce culturable populations. Our results reinforce the importance to use molecular tools to monitor viable pathogens in food processing plants to avoid underestimating the amounts of cells using only methods based on cell culture.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.012
      Issue No: Vol. 244 (2017)
       
  • Antibacterial effect of 405±5nm light emitting diode illumination against
           Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella on the
           surface of fresh-cut mango and its influence on fruit quality
    • Authors: Min-Jeong Kim; Chee Hwa Tang; Woo Suk Bang; Hyun-Gyun Yuk
      Pages: 82 - 89
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Min-Jeong Kim, Chee Hwa Tang, Woo Suk Bang, Hyun-Gyun Yuk
      To investigate a potential of 405±5nm light emitting diode (LED) as a novel technology for food preservation, the antibacterial effect of 405±5nm LED on Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella spp. on the surface of fresh-cut mango and its influence on fruit quality were evaluated at different storage temperatures. LED-illumination inactivated 1.0–1.6 logCFU/cm2 of populations at 4 and 10°C for 36–48h (total dose, 2.6–3.5kJ/cm2) regardless of bacterial species, while those on non-illuminated mange remained unchanged or slightly increased during storage. At 20°C for 24h (total dose, 1.7kJ/cm2), non-illuminated E. coli O157:H7 and Salmonella gradually grew, whereas LED-illumination reduced 1.2 log of Salmonella and inhibited the growth of E. coli O157:H7. Unlike these, non-illuminated L. monocytogenes cells rapidly increased to 7.3 log, while illuminated cells reached 4.6 log, revealing that LED-illumination delayed their growth. There were no significant (P >0.05) differences in color, antioxidant capacity, ascorbic acid, β-carotene, and flavonoid between non-illuminated and illuminated cut mangoes, regardless of storage temperature. These results suggest that 405±5nm LEDs in combination with chilling temperatures could be applied to preserve fresh-cut fruits without deterioration of physicochemical quality of fruits at food establishments, minimizing the risk of foodborne disease.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.023
      Issue No: Vol. 244 (2017)
       
  • Vibrio parahaemolyticus O4:K8 forms a potential predominant clone in
           southern China as detected by whole-genome sequence analysis
    • Authors: Baisheng Li; Xingfen Yang; Hailing Tan; Bixia Ke; Dongmei He; Changwen Ke; Yonghui Zhang
      Pages: 90 - 95
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Baisheng Li, Xingfen Yang, Hailing Tan, Bixia Ke, Dongmei He, Changwen Ke, Yonghui Zhang
      Vibrio parahaemolyticus has been the most common food-borne pathogen in southern China, especially the O3:K6 pandemic clone and its serovariants. Recently, the serotype O4:K8 became more and more prevalent in southern China, which was different from the O3:K6 pandemic clone. Thus, the aim of the present work was to elucidate the molecular characteristics of the O4:K8. Some O3:K6 pandemic clone and its serovariants isolated in the same period were selected for comparative analysis, which were still dominant clone locally. The whole genome sequencing (WGS) was applied to characterize 20 strains of V. parahaemolyticus isolated from food-borne diarrheal cases and belonging to the serotype O4:K8, O3:K6 and O1:KUT (untypable), prevalent serotypes in recent southern China. The results showed that all these isolates were positive for the thermostable direct hemolysin gene (tdh), while negative for the TDH-related hemolysin gene (trh). We compared the V. parahaemolyticus strains to those of 31 strains isolated overseas and were available from NCBI genome database. A WGS-SNPs phylogenetic analysis of all the genomes revealed that the strains formed an important genetic lineage, which was genetically distinct from the O3:K6, O1:KUT and other internationals strains. Comparative genome analysis also revealed that all the O4:K8 strains carried the entire T3SS-1 and VpaI-7 (T3SS-2) regions, the most important virulent elements of the O3:K6 pandemic clone. However, all the O4:K8 strains lacked the entire VpaI-1 and VpaI-4 regions and carried only few ORFs of the VpaI-5 and VpaI-6, which were considered to be unique among post-1995 strains belonging to the O3:K6 pandemic clone. Our data showed that the O4:K8 strains possessed the virulence factors similar to the O3:K6 pandemic clone, which may have enabled them to become prevalent in southern China. Our study also revealed that WGS-bases analysis may help improve understanding epidemiology of this bacterium in food-borne disease surveillance.

      PubDate: 2017-01-07T18:44:20Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.001
      Issue No: Vol. 244 (2017)
       
  • Sulfur dioxide addition at crush alters Saccharomyces cerevisiae strain
           composition in spontaneous fermentations at two Canadian wineries
    • Authors: Sydney C. Morgan; Chrystal M. Scholl; Natasha L. Benson; Morgan L. Stone; Daniel M. Durall
      Pages: 96 - 102
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Sydney C. Morgan, Chrystal M. Scholl, Natasha L. Benson, Morgan L. Stone, Daniel M. Durall
      During winemaking, sulfur dioxide (SO2) is often added prior to the onset of alcoholic fermentation to prevent the growth of spoilage microorganisms and to create an environment that promotes the rapid colonization of the grape must by Saccharomyces cerevisiae. Most recent research has focused on the impacts of SO2 additions on spoilage microorganisms or on the yeast community at a species level, but less is known about the impacts that SO2 additions have on S. cerevisiae populations. We investigated whether different levels of SO2 addition at crush (0, 20, or 40mg/L SO2) have an effect upon the relative abundance and composition of S. cerevisiae strains conducting spontaneous fermentations of two grape varietals at two commercial wineries. Yeast isolates collected from fermentations were identified to the strain level using microsatellite analysis. Commercial strains made up the majority (64–98%) of the S. cerevisiae strains isolated during fermentation, and most of these commercial strains were used as inoculants by their respective wineries. Different SO2 additions were found to significantly alter S. cerevisiae strain compositions at both wineries (p ≤0.002). The results of this study demonstrate that initial SO2 addition significantly alters the S. cerevisiae strain composition in spontaneous fermentations, and highlights the dominance of commercial strains in commercial winery environments. Because different yeast strains are known to produce different chemical and sensory profiles, our findings have important implications for winemakers. In addition, adding different concentrations of SO2 may be a way for winemakers to manage or control the strain composition during spontaneous fermentations.

      PubDate: 2017-01-15T18:57:17Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.025
      Issue No: Vol. 244 (2017)
       
  • PCR screening of an African fermented pearl-millet porridge metagenome to
           investigate the nutritional potential of its microbiota
    • Authors: Fabien Saubade; Christèle Humblot; Youna M. Hemery; Jean-Pierre Guyot
      Pages: 103 - 110
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Fabien Saubade, Christèle Humblot, Youna M. Hemery, Jean-Pierre Guyot
      Cereals are staple foods in most African countries, and many African cereal-based foods are spontaneously fermented. The nutritional quality of cereal products can be enhanced through fermentation, and traditional cereal-based fermented foods (CBFFs) are possible sources of lactic acid bacteria (LAB) with useful nutritional properties. The nutritional properties of LAB vary depending on the species and even on the strain, and the microbial composition of traditional CBFFs varies from one traditional production unit (TPU) to another. The nutritional quality of traditional CBFFs may thus vary depending on their microbial composition. As the isolation of potentially useful LAB from traditional CBFFs can be very time consuming, the aim of this study was to use PCR to assess the nutritional potential of LAB directly on the metagenomes of pearl-millet based fermented porridges (ben-saalga) from Burkina Faso. Genes encoding enzymes involved in different nutritional activities were screened in 50 metagenomes extracted from samples collected in 10 TPUs in Ouagadougou. The variability of the genetic potential was recorded. Certain genes were never detected in the metagenomes (genes involved in carotenoid synthesis) while others were frequently detected (genes involved in folate and riboflavin production, starch hydrolysis, polyphenol degradation). Highly variable microbial composition - assessed by real-time PCR - was observed among samples collected in different TPUs, but also among samples from the same TPU. The high frequency of the presence of genes did not necessarily correlate with in situ measurements of the expected products. Indeed, no significant correlation was found between the microbial variability and the variability of the genetic potential. In spite of the high rate of detection (80%) of both genes folP and folK, encoding enzymes involved in folate synthesis, the folate content in ben-saalga was rather low (median: 0.5μg/100g fresh weight basis). This work highlighted the limit of evaluating the nutritional potential of the microbiota of traditional fermented foods by the only screening of genes in metagenomes, and suggests that such a screening should be completed by a functional analysis.

      PubDate: 2017-01-15T18:57:17Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.020
      Issue No: Vol. 244 (2017)
       
  • Efficacy of vacuum steam pasteurization for inactivation of Salmonella PT
           30, Escherichia coli O157:H7 and Enterococcus faecium on low moisture
           foods
    • Authors: Manoj K. Shah; Gladys Asa; Julie Sherwood; Kari Graber; Teresa M. Bergholz
      Pages: 111 - 118
      Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244
      Author(s): Manoj K. Shah, Gladys Asa, Julie Sherwood, Kari Graber, Teresa M. Bergholz
      Low moisture foods such as nuts, spices, and seeds have been implicated in several outbreaks due to Salmonella or E. coli O157:H7 contamination. Such foods may be consumed raw, and can be used as ingredients in other food products. While numerous thermal inactivation studies have been conducted for Salmonella on nuts, studies on other seeds and grains are minimal. Product water activity can influence the thermal resistance of pathogens, where thermal resistance increases as water activity decreases, leading to a requirement for higher temperatures and longer exposure times to achieve significant reduction of pathogen numbers. Vacuum steam pasteurization uses steam under vacuum, which can be operated at temperatures above and below 100°C. The objective of this study was to determine the efficacy of vacuum steam pasteurization for inactivation of pathogens on whole flaxseed, quinoa, sunflower kernels, milled flaxseed and whole black peppercorns. The use of E. faecium as a potential surrogate for Salmonella and E. coli O157:H7 in vacuum steam pasteurization was also evaluated. Pasteurization for 1min at 75°C yielded average log reductions of 5.48±1.22, 5.71±0.40 and 5.23±0.61 on flaxseed, 4.29±0.92, 5.89±0.26 and 2.39±0.83 on quinoa, and 4.01±0.74, 5.40±0.83 and 2.99±0.92 on sunflower kernels for Salmonella PT 30, E. coli O157:H7 and E. faecium, respectively. Similarly, on milled flaxseed and black peppercorns average log reductions of 3.02±0.79 and 6.10±0.64CFU/g were observed for Salmonella PT 30 after 1min of treatment at 75°C but, on average, >6.0 log reductions were observed after pasteurization at 85°C. Our data demonstrate that vacuum steam pasteurization can be effectively used to reduce pathogens on these low moisture foods at temperature as low as 75 and 85°C, and that E. faecium may be used as a potential surrogate for Salmonella PT 30 and E. coli O157:H7.

      PubDate: 2017-01-15T18:57:17Z
      DOI: 10.1016/j.ijfoodmicro.2017.01.003
      Issue No: Vol. 244 (2017)
       
  • ICFMH Announcment
    • Abstract: Publication date: 6 March 2017
      Source:International Journal of Food Microbiology, Volume 244


      PubDate: 2017-02-06T01:30:06Z
       
  • Comparative sequence analysis of enteroaggregative Escherichia coli
           heat-stable enterotoxin 1 identified in Korean and Japanese Escherichia
           coli strains
    • Authors: Dong Joo Seo; SunKeum Choi; Su Been Jeon; Suntak Jeong; Hyunkyung Park; Bog-Hieu Lee; Geun-Bae Kim; Soo-Jin Yang; Yoshikazu Nishikawa; Changsun Choi
      Pages: 1 - 8
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Dong Joo Seo, SunKeum Choi, Su Been Jeon, Suntak Jeong, Hyunkyung Park, Bog-Hieu Lee, Geun-Bae Kim, Soo-Jin Yang, Yoshikazu Nishikawa, Changsun Choi
      The aim of this study was to compare the sequence of the astA gene found in 8 Korean and 11 Japanese Escherichia coli isolates. Conventional PCR was used to amplify the astA gene from the chromosomal and plasmid DNA preparation samples of each isolate using commercial DNA extraction kits. Cloning of the PCR products, sequence analysis, and pulse field gel electrophoresis (PFGE) were sequentially performed. An identical copy of astA in each isolate were found for 8 Korean and 8 Japanese E. coli strains isolated from bovine, porcine, and healthy human carriers. Among these, 1 Korean and 4 Japanese isolates carried a stop mutation at residue 16. Three Japanese outbreak strains (V199, V638, and 96-127-23) carried multiple clones of astA gene with multiple amino acids changes at residues 11, 16, 20, 23, 30, 33, and 34. Compared with the non-diarrheal isolates, clonal diversity and sequence variations of the astA gene in outbreak isolates may be associated with virulence potential of EAST1.

      PubDate: 2016-12-08T04:23:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.11.017
      Issue No: Vol. 243 (2016)
       
  • A proteomic approach for rapid identification of Weissella species
           isolated from Korean fermented foods on MALDI-TOF MS supplemented with an
           in-house database
    • Authors: Eiseul Kim; Youngjae Cho; Yoonju Lee; Sun-Kyung Han; Chang-Gyeom Kim; Dong-Won Choo; Young-Rok Kim; Hae-Yeong Kim
      Pages: 9 - 15
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Eiseul Kim, Youngjae Cho, Yoonju Lee, Sun-Kyung Han, Chang-Gyeom Kim, Dong-Won Choo, Young-Rok Kim, Hae-Yeong Kim
      Weissella are obligate heterofermentative lactic acid bacteria belonging to the Leuconostocaceae family. Some Weissella can be found in salted and fermented foods, such as kimchi and jeotgal, and plays an important role in the fermentation process. In the present study, for the first time, a rapid and accurate identification method for Weissella species from kimchi and jeotgal was developed based on MALDI-TOF MS, supplemented with an in-house database. Of the 135 Weissella spectra aligned with the MALDI bioTyper database, 56 isolates (41.5%) yielded no reliable identification results with low log scores (<1.7). After registering the spectra of six Weissella reference strains, all of the isolates were correctly identified, of which 113 (83.7%) and 22 (16.3%) were identified at the species and genus level, respectively. Moreover, a dendrogram generated by protein profiles of the different Weissella species clearly presented distinctive clusters, and PCA analysis separated the spectra of Weissella species into four clusters. In comparing food origins, different Weissella species were identified from two fermented foods. W. soli and W. cibaria were isolated from kimchi, while W. thailandensis and W. halotolerans were isolated from jeotgal. The results of our proteomic approach confirm that the MALDI bioTyper database, with our in-house Weissella database, is sufficient for Weissella identification. The MALDI-TOF MS method provides fast and reliable discrimination between different species in the genus Weissella and, therefore, will be useful for safety control in fish farms or in the production of fermented foods. This method can also be applied to the control of opportunistic pathogenic Weissella in human clinical infections.

      PubDate: 2016-12-08T04:23:20Z
      DOI: 10.1016/j.ijfoodmicro.2016.11.027
      Issue No: Vol. 243 (2016)
       
  • Linking wine lactic acid bacteria diversity with wine aroma and flavour
    • Authors: Maria Stella Cappello; Giacomo Zapparoli; Antonio Logrieco; Eveline J Bartowsky
      Pages: 16 - 27
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Maria Stella Cappello, Giacomo Zapparoli, Antonio Logrieco, Eveline J Bartowsky
      In the last two decades knowledge on lactic acid bacteria (LAB) associated with wine has increased considerably. Investigations on genetic and biochemistry of species involved in malolactic fermentation, such as Oenococcus oeni and of Lactobacillus have enabled a better understand of their role in aroma modification and microbial stability of wine. In particular, the use of molecular techniques has provided evidence on the high diversity at species and strain level, thus improving the knowledge on wine LAB taxonomy and ecology. These tools demonstrated to also be useful to detect strains with potential desirable or undesirable traits for winemaking purposes. At the same time, advances on the enzymatic properties of wine LAB responsible for the development of wine aroma molecules have been undertaken. Interestingly, it has highlighted the high intraspecific variability of enzymatic activities such as glucosidase, esterase, proteases and those related to citrate metabolism within the wine LAB species. This genetic and biochemistry diversity that characterizes wine LAB populations can generate a wide spectrum of wine sensory outcomes. This review examines some of these interesting aspects as a way to elucidate the link between LAB diversity with wine aroma and flavour. In particular, the correlation between inter- and intra-species diversity and bacterial metabolic traits that affect the organoleptic properties of wines is highlighted with emphasis on the importance of enzymatic potential of bacteria for the selection of starter cultures to control MLF and to enhance wine aroma.

      PubDate: 2016-12-14T17:10:50Z
      DOI: 10.1016/j.ijfoodmicro.2016.11.025
      Issue No: Vol. 243 (2016)
       
  • Single vs multiple-spore inoculum effect on growth kinetic parameters and
           modeled probabilities of growth and aflatoxin B1 production of Aspergillus
           flavus on pistachio extract agar
    • Authors: Laila Aldars-García; Vicente Sanchis; Antonio J. Ramos; Sonia Marín
      Pages: 28 - 35
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Laila Aldars-García, Vicente Sanchis, Antonio J. Ramos, Sonia Marín
      The objective of the present study was to assess the differences in modeled growth/AFB1 production probability and kinetic growth parameters for Aspergillus flavus inoculated as single spores or in a concentrated inoculation point (~500 spores). The experiment was carried out at 25°C and at two water activities (0.85 and 0.87) on pistachio extract agar (3%). Binary data obtained from growth and AFB1 studies were modeled using linear logistic regression analysis. The radial growth curve for each colony was fitted to a linear model for the estimation of the lag phase for growth and the mycelial growth rate. In general, radial growth rate and lag phase for growth were not normally distributed and both of them were affected by the inoculation type, with the lag phase for growth being more affected. Changing from the multiple spore to the single spore inoculation led to a delay of approximately 3–5days on the lag phase and higher growth rates for the multiple spore experiment were found. The same trend was observed on the probability models, with lower predicted probabilities when colonies came up from single spores, for both growth and AFB1 production probabilities. Comparing both types of models, it was concluded that a clear overestimation of the lag phase for growth occurred using the linear model, but only in the multiple spore experiment. Multiple spore inoculum gave very similar estimated time to reach some set probabilities (t10, t50 and t100) for growth or AFB1 production due to the abruptness of the logistic curve developed. The observed differences suggest that inoculum concentration greatly affects the outcome of the predictive models, the estimated times to growth/AFB1 production being much earlier for the concentrated inoculum than for a single spore colony (up to 9days). Thus the number of spores used to generate data in predictive mycology experiments should be carefully controlled in order to predict as accurately as possible the fungal behavior in a foodstuff.

      PubDate: 2016-12-14T17:10:50Z
      DOI: 10.1016/j.ijfoodmicro.2016.11.026
      Issue No: Vol. 243 (2016)
       
  • Digital RT-PCR method for hepatitis A virus and norovirus quantification
           in soft berries
    • Authors: Audrey Fraisse; Coralie Coudray-Meunier; Sandra Martin-Latil; Catherine Hennechart-Collette; Sabine Delannoy; Patrick Fach; Sylvie Perelle
      Pages: 36 - 45
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Audrey Fraisse, Coralie Coudray-Meunier, Sandra Martin-Latil, Catherine Hennechart-Collette, Sabine Delannoy, Patrick Fach, Sylvie Perelle
      Raw fruits may harbour many pathogens of public health concern including enteric viruses, which are the leading cause of foodborne outbreaks. Recently, consumption of soft berries has been associated with increasing reports of norovirus and hepatitis A virus outbreaks in Europe. Due to their low infectious doses and low concentrations in food samples, an efficient and sensitive analytical method is required for virus detection. In this study we explored two different ways to improve the reference method for the detection of enteric viruses in soft fruits (ISO/TS 15216-1; 15216-2): an additional purification step after RNA extraction; and the detection of enteric viral genome by an absolute quantification method (microfluidic digital RT-PCR). Both of these approaches led to an improvement of enteric virus detection in soft berries by greatly lowering PCR inhibition, raising viral extraction efficiencies and enabling validation of controls using pure RNA extracts. The PCR inhibitor removal step can be easily included in the routine method. Absolute quantification by digital RT-PCR may be a relevant alternative method to standardize quantification of enteric viruses in foodstuffs.

      PubDate: 2016-12-14T17:10:50Z
      DOI: 10.1016/j.ijfoodmicro.2016.11.022
      Issue No: Vol. 243 (2016)
       
  • A minireview on the in vitro and in vivo experiments with anti-Escherichia
           coli O157:H7 phages as potential biocontrol and phage therapy agents
    • Authors: Salehe Sabouri; Zargham Sepehrizadeh; Sahar Amirpour-Rostami; Mikael Skurnik
      Pages: 52 - 57
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Salehe Sabouri, Zargham Sepehrizadeh, Sahar Amirpour-Rostami, Mikael Skurnik
      Phage therapy is an old method of combating bacterial pathogens that has recently been taken into consideration due to the alarming spread of antibiotic resistance. Escherichia coli O157:H7 is a foodborne pathogen that causes hemorrhagic colitis and life-threatening Hemolytic Uremic Syndrome (HUS). There are several studies on isolation of specific phages against E. coli O157:H7 and more than 60 specific phages have been published so far. Although in vitro experiments have been successful in elimination or reduction of E. coli O157:H7numbers, in vivo experiments have not been as promising. This may be due to escape of bacteria to locations where phages have difficulties to enter or due to the adverse conditions in the gastrointestinal tract that affect phage viability and proliferation. To get around the latter obstacle, an alternative phage delivery method such as polymer microencapsulation should be tried. While the present time results are not very encouraging the work should be continued as more efficient phage treatment regimens might be found in future.

      PubDate: 2016-12-14T17:10:50Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.004
      Issue No: Vol. 243 (2016)
       
  • Prevalence and antimicrobial susceptibility of Acinetobacter spp. isolated
           from meat
    • Authors: Ana Carvalheira; Rocio Casquete; Joana Silva; Paula Teixeira
      Pages: 58 - 63
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Ana Carvalheira, Rocio Casquete, Joana Silva, Paula Teixeira
      The prevalence and antibiotic resistance of Acinetobacter spp. from fifty samples of meat (chicken, turkey, beef and pork) were evaluated. Acinetobacter spp. was recovered from all samples and the clonal relatedness of 223 isolates identified to belong to the genus Acinetobacter was established by PFGE. A high genetic diversity was observed and 166 isolates from different samples, 141 representing different PFGE profiles, were further identified to the species level by rpoB gene sequencing. Thirteen distinct Acinetobacter species were identified among 156 isolates. The remaining ten isolates may represent three putatively novel species since rpoB sequence homologies with type strains of all available described Acinetobacter species, were <95%. The most common species was Acinetobacter guillouiae with a prevalence of 34.9%. However 18.7% of the strains belong to the Acinetobacter baumannii group (n =31) which include the species Acinetobacter baumannii (n =7), Acinetobacter pittii (n =12), Acinetobacter seifertii (n =8) and Acinetobacter nosocomialis (n =4) that are the species most frequently associated with nosocomial infections worldwide. In general, strains were resistant to some of the antimicrobials most frequently used to treat Acinetobacter infections such as piperacillin-tazobactam (64.9% of strains resistant), ceftazidime (43.5%), ciprofloxacin (42.9%), as well as to colistin (41.7%) and polymyxin B (35.1%), the last-resort drugs to treat infections caused by multidrug-resistant Acinetobacter. The percentage of resistant strains to trimethoprim-sulfamethoxazole, tetracycline, aminoglycosides (amikacin and tobramycin) and ampicillin-sulbactam was >10% (23.2%, 23.2%, 14.3%, 12.5%, 12.5%, respectively). However, resistances to meropenem, imipenem and minocycline were only sporadically observed (8.3%, 1.2% and 1.2%, respectively). Overall, 51.2% of the strains were considered as multidrug-resistant (MDR) and 9.6% as extensively drug-resistant (XDR). The prevalence of MDR strains within the A. baumannii group (38.7%) was lower than the prevalence within the others species identified (54.1%). Therefore, food of animal origin may be a vehicle of spread Acinetobacter strains resistant to several antibiotics in the community and in the hospital setting environment. This may led to nosocomial and community-acquired infections in susceptible individuals.

      PubDate: 2016-12-22T15:57:11Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.001
      Issue No: Vol. 243 (2016)
       
  • Thermal inactivation and sublethal injury kinetics of Salmonella enterica
           and Listeria monocytogenes in broth versus agar surface
    • Authors: Xiang Wang; Frank Devlieghere; Annemie Geeraerd; Mieke Uyttendaele
      Pages: 70 - 77
      Abstract: Publication date: 21 February 2017
      Source:International Journal of Food Microbiology, Volume 243
      Author(s): Xiang Wang, Frank Devlieghere, Annemie Geeraerd, Mieke Uyttendaele
      The objective of the present study was to compare the thermal inactivation and sublethal injury kinetics of Salmonella enterica and Listeria monocytogenes in broth (suspended cells) and on solid surface (agar-seeded cells). A 3-strain cocktail of S. enterica or L. monocytogenes inoculated in broth or on agar was subjected to heating in a water bath at various set temperatures (55.0, 57.5 and 60.0°C for S. enterica and 60.0, 62.5 and 65°C for L. monocytogenes). The occurrence of sublethally injured cells was determined by comparing enumerations on nonselective (TSAYE) and selective (XLD or ALOA) media. Results showed that the inactivation curves obtained from selective media were log-linear, and significant shoulders (p <0.05) were observed on some of the inactivation curves from TSAYE media. The D-values derived from the total population were higher than those from the uninjured cells. Generally, cells on agar surface exhibited higher heat resistance than those in broth. For S. enterica, cell injury increased with the exposure time, no difference was observed when treated at temperatures from 55.0 to 60.0°C, while for L. monocytogenes, cell injury increased significantly with heating time and treatment temperature (from 60.0 to 65°C). Moreover, the degree of sublethal injury affected by thermal treatment in broth or on agar surface depended upon the target microorganism. Higher proportions of injured S. enterica cells were observed for treatment in broth than on agar surface, while the opposite was found for L. monocytogenes. The provided information may be used to assess the efficacy of thermal treatment processes on surfaces for inactivation of S. enterica and L. monocytogenes, and it provides insight into the sublethally injured survival state of S. enterica and L. monocytogenes treated in liquid or on solid food.

      PubDate: 2016-12-22T15:57:11Z
      DOI: 10.1016/j.ijfoodmicro.2016.12.008
      Issue No: Vol. 243 (2016)
       
 
 
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