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  Subjects -> BIOLOGY (Total: 2834 journals)
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MICROBIOLOGY (240 journals)                  1 2 3     

Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 6)
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: 3)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Microbiology Research     Open Access   (Followers: 1)
Algorithms for Molecular Biology     Open Access   (Followers: 6)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 15)
American Journal of Microbiological Research     Open Access  
American Journal of Microbiology     Open Access   (Followers: 16)
American Journal of Molecular Biology     Open Access   (Followers: 2)
American Journal of Stem Cell Research     Open Access   (Followers: 1)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 5)
Annals of Microbiology     Hybrid Journal   (Followers: 9)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 24)
Antimicrobial Agents and Chemotherapy     Full-text available via subscription   (Followers: 16)
Applied and Environmental Microbiology     Full-text available via subscription   (Followers: 34)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 8)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 30)
Archives of Microbiology     Hybrid Journal   (Followers: 4)
Avicenna Journal of Clinical Microbiology and Infection     Open Access  
Bangladesh Journal of Medical Microbiology     Open Access  
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
Bio-Research     Full-text available via subscription  
BioArchitecture     Full-text available via subscription  
Biocell     Open Access   (Followers: 1)
Bioethanol     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 4)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Biomolecular Detection and Quantification     Open Access  
Biomolecules     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 8)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases & Medical Microbiology     Hybrid Journal   (Followers: 2)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 4)
Cell Biology : Research & Therapy     Hybrid Journal  
Cell Host & Microbe     Full-text available via subscription   (Followers: 10)
Cell Medicine     Open Access  
Cell Regeneration     Open Access  
Cell Stem Cell     Full-text available via subscription   (Followers: 24)
CellBio     Open Access  
Cells     Open Access   (Followers: 1)
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 9)
Cellular and Molecular Biology Letters     Open Access   (Followers: 1)
Cellular Microbiology     Hybrid Journal   (Followers: 5)
Cellular Senescence and Therapy     Open Access  
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (Followers: 2)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (Followers: 17)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 4)
Clinical Microbiology Reviews     Full-text available via subscription   (Followers: 10)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 9)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 8)
Current Clinical Microbiology Reports     Hybrid Journal  
Current Issues in Molecular Biology     Open Access   (Followers: 1)
Current Microbiology     Hybrid Journal   (Followers: 6)
Current Molecular Biology Reports     Hybrid Journal  
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 19)
Current Tissue Engineering     Hybrid Journal   (Followers: 1)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 4)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 6)
Disease and Molecular Medicine     Open Access   (Followers: 1)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (Followers: 2)
Environmental Microbiology     Hybrid Journal   (Followers: 14)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 3)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 5)
Epigenetics of Degenerative Diseases     Open Access   (Followers: 3)
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 11)
European Journal of Microbiology and Immunology     Open Access   (Followers: 8)
Experimental and Molecular Pathology     Hybrid Journal   (Followers: 5)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 6)
Fems Microbiology Letters     Hybrid Journal   (Followers: 14)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 19)
Fermentation     Open Access  
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 13)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 2)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 2)
Frontiers in Cellular Neuroscience     Open Access   (Followers: 2)
Frontiers in Microbiology     Open Access   (Followers: 6)
Frontiers in Molecular Neuroscience     Open Access   (Followers: 1)
Future Microbiology     Full-text available via subscription   (Followers: 2)
Future Virology     Full-text available via subscription   (Followers: 6)
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: 1)
Gut Microbes     Full-text available via subscription   (Followers: 3)
IAWA Journal     Hybrid Journal  
Indian Journal of Microbiology     Hybrid Journal   (Followers: 1)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 6)
Inside the Cell     Open Access  
International Arabic Journal of Antimicrobial Agents     Open Access   (Followers: 5)

        1 2 3     

Journal Cover   International Journal of Food Microbiology
  [SJR: 1.614]   [H-I: 121]   [13 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0168-1605
   Published by Elsevier Homepage  [2812 journals]
  • Investigation of the protective effect of whey proteins on lactococcal
           phages during heat treatment at various pH
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Hany Geagea , Ahmed I. Gomaa , Gabriel Remondetto , Sylvain Moineau , Muriel Subirade
      The incorporation of whey protein concentrates (WPC) into cheese is a risky process due to the potential contamination with thermo-resistant phages of lactic acid bacteria (LAB). Furthermore, whey proteins can protect phages during heat treatment, thereby increasing the above risk. The main objective of this work was to understand this protective effect in order to better control LAB phages and maximize whey recycling in the cheese industry. First, the inactivation of a previously characterized thermo-resistant lactococcal virulent phage (P1532) was investigated at 95°C in WPC, in individual whey components β-lactoglobulin, α-lactalbumin, and bovine serum albumin as well as under different heat and pH conditions. The structural changes of the tested proteins were also monitored by transmission FTIR spectroscopy. Phage inactivation results indicated that the protective effect of whey proteins was pH and time dependent at 95°C and was not restricted to one component. FTIR spectra suggest that the protection is related to protein molecular structures and to the level of protein aggregates, which was more pronounced in acidic conditions. Moreover, the molecular structure of the three proteins tested was differently influenced by pH and the duration of the heat treatment. This work confirms the protective effect of WPC on phages during heat treatment and offers the first hint to explain such phenomenon. Finding the appropriate treatment of WPC to reduce the phage risk is one of the keys to improving the cheese manufacturing process.


      PubDate: 2015-07-01T17:31:31Z
       
  • Comparative analysis of antimicrobial resistance and genetic diversity of
           Campylobacter from broilers slaughtered in Poland
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Kinga Wieczorek , Edyta Denis , Jacek Osek
      In the current study, the relationship of Campylobacter jejuni and Campylobacter coli strains isolated at slaughter was investigated using comparative analysis of antimicrobial resistance (AMR), virulence gene (VG) and PFGE profiling. A total of 254 Campylobacter isolates from poultry caeca and corresponding carcasses, including 139 C. jejuni and 115 C. coli strains were tested. The most prevalent resistance profiles observed in C. jejuni were ciprofloxacin, nalidixic acid and tetracycline (46 out of 139, 33.1% isolates) as well as ciprofloxacin, nalidixic acid, tetracycline and streptomycin among C. coli strains (34 out of 115, 29.6%). Multi-resistance was found more frequently among C. coli than C. jejuni (P <0.05). The presence of 11 virulence genes exhibited 19 different VG profiles in Campylobacter isolates tested. All Campylobacter strains were classified into 154 different PFGE types. Among them, 56 profiles (28 C. jejuni and 28 C. coli) were common for at least two isolates including 9 clusters covering from 4 to 9 strains. Campylobacter composite types generated by a combination of 154 PFGE types, 10 AMR profiles and 19 VG patterns divided 178 distinct types with 95% similarity. The majority of the composite profiles (76 for C. jejuni and 58 for C. coli; 75.3% in total) included only one bacterial isolate. Furthermore, 11 pairs of C. jejuni and 12 pairs of C. coli from caeca and the corresponding carcasses isolated from the same places possessed the identical PFGE, AMR and VG patterns. This study demonstrated that C. jejuni and C. coli isolated from poultry in Poland showed to have a high genetic diversity and a weak clonal population structure. However, the composite analysis revealed a strong evidence for cross-contamination of chicken carcasses during the slaughter process. Additionally, our results confirm that Campylobacter may easily contaminate poultry carcasses at slaughter process and spread around country. More than half of Campylobacter strains tested (50.4%) were resistant to at least two classes of antimicrobials, i.e. quinolones and tetracyclines, which may cause a public health risk.


      PubDate: 2015-07-01T17:31:31Z
       
  • Phenotypic and genotypic characterization of lactic acid bacteria isolated
           from raw goat milk and effect of farming practices on the dominant species
           of lactic acid bacteria
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Hélène Tormo , Djamila Ali Haimoud Lekhal , C. Roques
      Lactic acid bacteria, in particular Lactococcus lactis, play a decisive role in the cheese making process and more particularly in lactic cheeses which are primarily produced on goat dairy farms. The objective of this study was therefore to identify the main lactic acid bacteria found in raw goats' milk from three different regions in France and evaluate if certain farming practices have an effect on the distribution of species of lactic acid bacteria in the various milk samples. Identification at genus or species level was carried out using phenotypic tests and genotypic methods including repetitive element REP-PCR, species-specific PCR and 16S rRNA gene sequencing. The distribution of the main bacterial species in the milk samples varied depending on farms and their characteristics. Out of the 146 strains identified, L. lactis was the dominant species (60% of strains), followed by Enterococcus (38%) of which Enterococcus faecalis and Enterococcus faecium. Within the species L. lactis, L. lactis subsp lactis was detected more frequently than L. lactis subsp cremoris (74% vs. 26%). The predominance of L. lactis subsp cremoris was linked to geographical area studied. It appears that the animals' environment plays a role in the balance between the dominance of L. lactis and enterococci in raw goats' milk. The separation between the milking parlor and the goat shed (vs no separation) and only straw in the bedding (vs straw and hay) seems to promote L. lactis in the milk (vs enterococci).


      PubDate: 2015-07-01T17:31:31Z
       
  • Development of an FgMito assay: A highly sensitive mitochondrial based
           qPCR assay for quantification of Fusarium graminearum sensu stricto
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Tomasz Kulik , Anna Ostrowska , Maciej Buśko , Matias Pasquali , Marco Beyer , Sebastian Stenglein , Dariusz Załuski , Jakub Sawicki , Kinga Treder , Juliusz Perkowski
      An ascomycete fungus, Fusarium graminearum sensu stricto (s.s.), is the major cause of Fusarium head blight (FHB), a devastating disease of cereals worldwide. The fungus contaminates crops with mycotoxins, which pose a serious threat to food and feed safety. In this study, we developed a highly sensitive mitochondrial based qPCR assay (FgMito qPCR) for quantification of F. graminearum s.s. To ensure high sensitivity of the assay, primers and a Minor-groove binding (MGB) probe were designed based on multi-copy mitochondrial DNA. The FgMito assay was successfully validated against a range of geographically diverse F. graminearum s.s. strains to ensure uniformity of the assay at an intraspecific level, as well as with other fungal species to ensure specificity. The assay was further evaluated in terms of efficiency and sensitivity against a test panel of different F. graminearum s.s. strains with various levels of pure fungal DNA and in the presence of wheat background DNA. The results showed a high efficiency of the assay developed, ranging from 93% to 101% with r 2-values of >0.99. We further showed that three low concentrations of fungal template 2pg, 0.6pg and 0.2pg could be reliably quantified in the presence of wheat background DNA. The FgMito assay was used to quantify F. graminearum s.s. DNA on 65 field samples from a range of hosts with defined levels of trichothecenes. We revealed a significant positive correlation between fungal DNA quantity and the sum of trichothecenes. Lastly, we showed a higher sensitivity of the FgMito assay than the nuclear based qPCR assay for F. graminearum s.s. by comparing Ct-values from both assays.


      PubDate: 2015-07-01T17:31:31Z
       
  • Decontamination of Pangasius fish (Pangasius hypophthalmus) with chlorine
           or peracetic acid in the laboratory and in a Vietnamese processing company
           
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Anh Ngoc Tong Thi , Imca Sampers , Sam Van Haute , Simbarashe Samapundo , Binh Ly Nguyen , Marc Heyndrickx , Frank Devlieghere
      This study evaluated the decontamination of Pangasius fillets in chlorine or peracetic acid treated wash water. First, the decontamination efficacy of the washing step with chlorinated water applied by a Vietnamese processing company during trimming of Pangasius fillets was evaluated and used as the basis for the experiments performed on a laboratory scale. As chlorine was only added at the beginning of the batch and used continuously without renewal for 239min; a rapid increase of the bacterial counts and a fast decrease of chlorine in the wash water were found. This could be explained by the rapid accumulation of organic matter (ca. 400mg O2/L of COD after only 24min). Secondly, for the experiments performed on a laboratory scale, a single batch approach (one batch of wash water for treating a fillet) was used. Chlorine and PAA were evaluated at 10, 20, 50 and 150ppm at contact times of 10, 20 and 240s. Washing with chlorine and PAA wash water resulted in a reduction of Escherichia coli on Pangasius fish which ranged from 0–1.0 and 0.4–1.4logCFU/g, respectively while less to no reduction of total psychrotrophic counts, lactic acid bacteria and coliforms on Pangasius fish was observed. However, in comparison to PAA, chlorine was lost rapidly. As an example, 53–83% of chlorine and 15–17% of PAA were lost after washing for 40s (COD=238.2±66.3mg O2/L). Peracetic acid can therefore be an alternative sanitizer. However, its higher cost will have to be taken into consideration. Where (cheaper) chlorine is used, the processors have to pay close attention to the residual chlorine level, pH and COD level during treatment for optimal efficacy.


      PubDate: 2015-07-01T17:31:31Z
       
  • Identification and mycotoxigenic capacity of fungi associated with pre-
           and postharvest fruit rots of pomegranates in Greece and Cyprus
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Loukas Kanetis , Stefanos Testempasis , Vlasios Goulas , Stylianos Samuel , Charalampos Myresiotis , George S. Karaoglanidis
      Pre- and postharvest fruit rots of fungal origin are an important burden for the pomegranate industry worldwide, affecting the produce both quantitatively and qualitatively. During 2013, local orchards were surveyed and 280 fungal isolates from Greece (GR) and Cyprus (CY) were collected from pomegranates exhibiting preharvest rot symptoms, and additional 153 isolates were collected postharvest from cold-stored fruit in GR. Molecular identification revealed that preharvest pomegranate fruit rots were caused predominately by species of the genera Aspergillus (Aspergillus niger and Aspergillus tubingensis) and Alternaria (Alternaria alternata, Alternaria tenuissima, and Alternaria arborescens). By contrast, postharvest fruit rots were caused mainly by Botrytis spp. and to a lesser extent by isolates of Pilidiella granati and Alternaria spp. Considering that a significant quota of the fungal species found in association with pomegranate fruit rots are known for their mycotoxigenic capacity in other crop systems, their mycotoxin potential was examined. Alternariol (AOH), alternariol monomethyl-ether (AME) and tentoxin (TEN) production was estimated among Alternaria isolates, whereas ochratoxin A (OTA) and fumonisin B2 (FB2) production was assessed within the black aspergilli identified. Overall in both countries, 89% of the Alternaria isolates produced AOH and AME in vitro, while TEN was produced only by 43.9%. In vivo production of AOH and AME was restricted to 54.2% and 31.6% of the GR and CY isolates, respectively, while none of the isolates produced TEN in vivo. Among black aspergilli 21.7% of the GR and 17.8% of the CY isolates produced OTA in vitro, while in vivo OTA was detected in 8.8% of the isolates from both countries. FB2 was present in vitro in 42.0% of the GR and 22.2% of the CY isolates, while in vivo the production was limited to 27.5% and 4.5% of the GR and the CY isolates, respectively. Our data imply that mycotoxigenic Alternaria and Aspergillus species not only constitute a significant subset of the fungal population associated with pomegranate fruit rots responsible for fruit deterioration, but also pose a potential health risk factor for consumers of pomegranate-based products.


      PubDate: 2015-07-01T17:31:31Z
       
  • Effect of cell immobilization on the growth dynamics of Salmonella
           Typhimurium and Escherichia coli at suboptimal temperatures
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Cindy Smet , Eva Van Derlinden , Laurence Mertens , Estefanía Noriega , Jan F. Van Impe
      Predictive microbiology has recently acknowledged the impact of the solid(like) food structure on microbial behavior. The presence of this solid(like) structure causes microorganisms to grow as colonies and no longer planktonically as in liquid. In this paper, the growth dynamics of Salmonella Typhimurium and Escherichia coli were studied as a function of temperature, considering different growth morphologies, i.e., (i) planktonic cells, (ii) immersed colonies and (iii) surface colonies. For all three growth morphologies, both microorganisms were grown in petri dishes. While E. coli was grown under optimal pH and water activity (aw), for S. Typhimurium pH and aw were adapted to 5.5 and 0.990. In order to mimic a solid(like) environment, 5% (w/v) gelatin was added. All petri dishes were incubated under static conditions at temperatures in the range [8.0°C–22.0°C]. Cell density was determined via viable plate counting. This work demonstrates that the growth morphology (planktonic vs. colony) has a negligible effect on the growth dynamics as a function of temperature. The observation of almost equal growth rates for planktonic cultures and colonies is in contrast to literature where, mostly, a difference is observed, i.e., μplanktonic cells ≥ μimmersed colonies ≥ μsurface colonies . This difference might be due to shaking of the liquid culture in these studies, which results in a nutrient and oxygen rich environment, in contrast to the diffusion-limited gel system. Experiments also indicate that lag phases for solid(like) systems are similar to those for the planktonic cultures, as can be found in literature for similar growth conditions. Considering the maximum cell density, no clear trend was deducted for either of the microorganisms. This study indicates that the growth parameters in the suboptimal temperature range do not depend on the growth morphology. For the considered experimental conditions, models previously developed for liquid environments can be used for solid(like) systems.


      PubDate: 2015-07-01T17:31:31Z
       
  • Ultraviolet-C light inactivation of Escherichia coli O157:H7 and Listeria
           monocytogenes on organic fruit surfaces
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Achyut Adhikari , Roopesh M. Syamaladevi , Karen Killinger , Shyam S. Sablani
      This study investigated UV-C light inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on the surface of organic apples, pears, strawberries, red raspberries and cantaloupes. Fruit surfaces spot inoculated with cocktail strains of E. coli O157:H7 and L. monocytogenes were exposed to UV-C doses up to 11.9kJ/m2 at 23°C. Fruit surface roughness, contact angle, and surface energy were determined and correlated with UV-C inactivation kinetics. Results demonstrate that bacterial pathogens on fruit surfaces respond differently to UV-C light exposure. E. coli O157:H7 on apple and pear surfaces was reduced by 2.9 and 2.1logCFU/g, respectively when treated with UV-C light at 0.92kJ/m2 (60s). For berries, the reduction of E. coli O157:H7 was lower with 2.0 (strawberry) and 1.1logCFU/g (raspberry) achieved after UV-C treatment at 7.2kJ/m2 (8min) and at 10.5kJ/m2 (12min), respectively. Similarly, a higher reduction of L. monocytogenes was observed on apple (1.6logCFU/g at 3.75kJ/m2) and pear (1.7logCFU/g at 11.9kJ/m2) surfaces compared to cantaloupe and strawberry surfaces (both achieved 1.0logCFU/g at 11.9kJ/m2). L. monocytogenes shows more resistance than E. coli O157:H7. Inactivation rates were higher for less hydrophobic fruits with smoother surfaces (apples and pears) as compared to fruits with rougher surfaces (cantaloupe, strawberry and raspberry). Findings indicate that UV-C light can effectively reduce E. coli O157:H7 and L. monocytogenes populations on fruit and berry surfaces. However, surface characteristics influence the efficacy of UV-C light.


      PubDate: 2015-07-01T17:31:31Z
       
  • Antimicrobial property and microstructure of micro-emulsion edible
           composite films against Listeria
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Mingming Guo , Tony Z. Jin , Madhav P. Yadav , Ruijin Yang
      Edible antimicrobial composite films from micro-emulsions containing all natural compounds were developed and their antimicrobial properties and microstructures were investigated. Chitosan, allyl isothiocyanate (AIT), barley straw arabinoxylan (BSAX), and organic acids (acetic, lactic and levulinic acids) were used as film-forming agent, antimicrobial agent, emulsifier, and solvent, respectively. Micro-emulsions were obtained using high pressure homogenization (HPH) processing at 138MPa for 3cycles. The composite films made from the micro-emulsions significantly (p<0.05) inactivated Listeria innocua in tryptic soy broth (TSB) and on the surface of ready-to-eat (RTE) meat samples, achieving microbial reductions of over 4logCFU/ml in TSB after 2days at 22°C and on meat samples after 35days at 10°C. AIT was a major contributor to the antimicrobial property of the films and HPH processing further enhanced its antimicrobial efficacy, while the increase of chitosan from 1.5% to 3%, or addition of acetic acid to the formulations didn't result in additional antimicrobial effects. This study demonstrated an effective approach to developing new edible antimicrobial films and coatings used for food applications.


      PubDate: 2015-07-01T17:31:31Z
       
  • Application of water-assisted pulsed light treatment to decontaminate
           raspberries and blueberries from Salmonella
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Yaoxin Huang , Robert Sido , Runze Huang , Haiqiang Chen
      We developed and evaluated a small scaled-up water-assisted pulsed light (WPL) system, in which berries were washed in a flume washer while being irradiated by pulsed light (PL). Hydrogen peroxide (H2O2) was used in combination with PL as an advanced oxidation process and chlorine wash was used as a control. The effects of organic load, water turbidity, berry type and PL energy output on the inactivation of Salmonella using the WPL system were investigated. The combination of WPL and 1% H2O2 (WPL–H2O2) was the most effective treatment which reduced Salmonella on raspberries and blueberries by 4.0 and >5.6logCFU/g, respectively, in clear water. When high organic load and SiO2, as a soil simulator, were added in wash water, the free chlorine level in chlorinated water decreased significantly (P <0.05); however, no significant difference (P >0.05) was observed for the decontamination efficacy of 1-min WPL–H2O2 treatment. Even in the presence of high organic load and water turbidity, no viable bacterial cells were recovered from the wash water, which showed that WPL–H2O2 could effectively prevent the risk of cross-contamination during treatment. Taken together, 1-min WPL treatment without H2O2 could provide a chemical free alternative to chlorine washing with similar and in some cases significantly higher bactericidal efficacy. Compared with chlorine washing, the combination of WPL and H2O2 resulted in significantly higher (P <0.05) reduction of Salmonella on berries, providing a novel intervention for processing of small berries intended for fresh-cut and frozen berry products.


      PubDate: 2015-07-01T17:31:31Z
       
  • Development of loop-mediated isothermal amplification to detect
           Streptococcus suis and its application to retail pork meat in Japan
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Sakura Arai , Mari Tohya , Ryoko Yamada , Ro Osawa , Ryohei Nomoto , Yoshiaki Kawamura , Tsutomu Sekizaki
      We here developed a novel loop-mediated isothermal amplification (LAMP) method to detect Streptococcus suis in raw pork meat. This method, designated LAMPSS, targeted the recombination/repair protein (recN) gene of S. suis and detected all serotypes of S. suis, except those taxonomically removed from authentic S. suis, i.e., serotypes 20, 22, 26, 32, 33, and 34. The specificity of LAMPSS was confirmed and its detection limit was 5.4cfu/reaction. Among the 966 raw pork meat samples examined, including sliced pork, minced pork, and the liver, tongue, heart, and small intestine, 255 samples tested positive with LAMPSS. The rate of contamination was higher in the organs than in pork. No significant difference was observed in the total bacterial count between LAMPSS-positive and -negative samples. The number of shops that provided LAMPSS-positive pork was slightly higher in those that sold swine organs and pork than in those that sold only pork, suggesting that cross contamination occurred from the organs to pork. Among the 255 which tested positive for LAMPSS, only 47 samples tested positive for the previously described LAMP specific for S. suis serotype 2. Two isolates of S. suis serotype 2, belonging to sequence type 28, which is potentially hazardous to humans, as well as those of some other serotypes were obtained from 19 out of 47 samples by combining LAMP with a replica plating method. These results suggest that LAMPSS will be a useful tool for the surveillance of raw pork meat in the retail market.


      PubDate: 2015-07-01T17:31:31Z
       
  • Toxigenic Clostridium difficile PCR ribotypes in edible marine bivalve
           molluscs in Italy
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Tiziana Troiano , Celine Harmanus , Ingrid M.J.G. Sanders , Vincenzo Pasquale , Stefano Dumontet , Federico Capuano , Vincenza Romano , Ed J. Kuijper
      Even though food of animal sources and different foodstuffs are well known to be potentially carrier of Clostridium difficile, few data are available on the occurrence of C. difficile in seafood. This work investigated the occurrence of C. difficile in edible bivalve molluscs in southern Italy. Out of the 925 investigated samples, 3.9% contained C. difficile. Eighteen strains harboured both genes for toxins A and B whereas 1 only had toxin B gene. Binary toxin genes were found in 22.2% of the isolates. The most frequently ribotypes found were 078/126 (22.2%), 010 (19.4%), and 001 (8.3%). All isolates were susceptible to metronidazole, vancomycin, fidaxomicin, and to the new semisynthetic thiopeptide antibiotic LFF571, whereas 19.4% of them were resistant to moxifloxacin, 30.5% to clindamycin, 38.8% to erythromycin, and 100% to ciprofloxacin. This study points out that edible molluscs could be a potential source of toxigenic C. difficile ribotypes and a potential risk for human health.


      PubDate: 2015-07-01T17:31:31Z
       
  • Restoring the selectivity of modified charcoal cefoperazone deoxycholate
           agar for the isolation of Campylobacter species using tazobactam, a
           β-lactamase inhibitor
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Shaun Smith , Joseph Meade , Kevina McGill , James Gibbons , Declan Bolton , Paul Whyte
      Extended spectrum β-lactamase (ESBL) producing Escherichia coli have emerged as a contaminant on modified charcoal cefoperazone deoxycholate agar (mCCDA) when attempting to selectively isolate Campylobacter spp. from poultry. E. coli are particularly problematic given their ability to grow under microaerophilic conditions and have been shown to outcompete Campylobacter species making Campylobacter detection or enumeration difficult. This paper recommends a novel method for restoring the selectivity of mCCDA using tazobactam, a β-lactamase inhibitor. The method significantly inhibited ESBL E. coli growth in spiked or naturally contaminated broiler caecal samples (p≤0.01) when compared to conventional mCCDA. This effect was seen at concentrations as low as 1mg/L tazobactam. TmCCDA 1 1 TmCCDA (tazobactam modified cefoperazone deoxycholate agar). was found to inhibit up to 8log10 CFU/mL of ESBL E. coli in mixed pure cultures and 7.5log10 CFU/mL in caecal samples. Furthermore TmCCDA concentrations up to 10mg/L had no statistically significant inhibitory effect (p≥0.05) on the recovery of a panel of 27 Campylobacter jejuni and 5 Campylobacter coli isolates when compared to conventional mCCDA. From this study it is suggested that tazobactam, which is more chemically stable than clavulanic acid or sulbactam, is more suitable for restoring the selectivity of mCCDA for the detection or isolation of campylobacters.


      PubDate: 2015-07-01T17:31:31Z
       
  • Prediction of spoilage of tropical shrimp (Penaeus notialis) under dynamic
           temperature regimes
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): D. Sylvain Dabadé , Paulin Azokpota , M.J. Robert Nout , D. Joseph Hounhouigan , Marcel H. Zwietering , Heidy M.W. den Besten
      The spoilage activity of Pseudomonas psychrophila and Carnobacterium maltaromaticum, two tropical shrimp (Penaeus notialis) spoilage organisms, was assessed in cooked shrimps stored at 0 to 28°C. Microbiological, chemical and sensory analyses were performed during storage. P. psychrophila had a higher growth rate and showed a higher spoilage activity at temperatures from 0 to 15°C, while at 28°C, C. maltaromaticum had a higher growth rate. The spoilage activity of P. psychrophila was found to be higher in cooked shrimp than in fresh shrimp. Observed shelf-life data of shrimps stored at constant temperatures were used to validate a previously developed model that predicts tropical shrimp shelf-life at constant storage temperatures. Models predicting the growth of the spoilage organisms as a function of temperature were constructed. The validation of these models under dynamic storage temperatures simulating temperature fluctuation in the shrimp supply chain showed that they can be used to predict the shelf-life of cooked and fresh tropical shrimps.


      PubDate: 2015-07-01T17:31:31Z
       
  • Microbiological diversity associated with the spontaneous wet method of
           coffee fermentation
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Suzana Reis Evangelista , Maria Gabriela da Cruz Pedroso Miguel , Cristina Ferreira Silva , Ana Carla Marques Pinheiro , Rosane Freitas Schwan
      The evaluation of the microbiota present during coffee wet fermentation was done in two distinct regions of Minas Gerais, Brazil: one farm in the South of Minas Gerais (Lavras=L) and another farm in the savannah region (Monte Carmelo=MC). The yeast population ranged from 2.48 to 4.92logCFU/g and from 2 to 4.81logCFU/g, the mesophilic bacteria population ranged from 3.83 to 8.47logCFU/g and from 5.37 to 7.36logCFU/g, and the LAB population ranged from 2.57 to 5.66logCFU/g and from 3.40 to 4.49logCFU/g in the L and MC farms, respectively. Meyerozyma caribbica and Hanseniaspora uvarum were the dominant yeasts in coffee wet fermentation at L farm, and Torulaspora delbrueckii was the dominant yeast at MC farm. The species Staphylococcus warneri and Erwinia persicina were the predominant bacteria at L farm, and Enterobacter asburiae and Leuconostoc mesenteroides were the dominant species at MC farm. Lactic acid was the principal acid detected, reaching 2.33g/kg at L farm and 1.40g/kg at MC farm by the end of the process. The volatiles composition was similar for roasted coffee from the two different regions and furans, acids, and alcohol were the main groups detected. Temporal Dominance Sensation (TDS) analyses showed that the coffee beverage from L farm was dominated by citrus and herbaceous sensory characteristics, while the coffee from MC farm was dominated by citrus, herbaceous, and nuts sensory characteristics. Evaluating the microbiota in these two regions was important in improving the knowledge of the microbial species present during coffee wet fermentation in Brazil.


      PubDate: 2015-07-01T17:31:31Z
       
  • Potential spoilage yeasts in winery environments: Characterization and
           proteomic analysis of Trigonopsis cantarellii
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Cauré Portugal , Luís Pinto , Miguel Ribeiro , Carmen Tenorio , Gilberto Igrejas , Fernanda Ruiz-Larrea
      Wine microbiota is complex and includes a wide diversity of yeast species. Few of them are able to survive under the restrictive conditions of dry red wines. In our study we detected and identified seven yeast species of the order Saccharomycetales that can be considered potential spoilers of wines due to physiological traits such as acidogenic metabolism and off-odor generation: Arthroascus schoenii, Candida ishiwadae, Meyerozyma guilliermondii, Pichia holstii, Pichia manshurica, Trigonopsis cantarellii, and Trigonopsis variabilis. Based on the prevalence of T. cantarellii isolates in the wine samples of our study, we further characterized this species, determined molecular and phenotypic features, and performed a proteomic analysis to identify differentially expressed proteins at mid-exponential growth phase in the presence of ethanol in the culture broth. This yeast species is shown to be able to grow in the presence of ethanol by expressing heat shock proteins (Hsp70, Hsp71) and a DNA damage-related protein (Rad24), and to be able to confer spoilage characteristics on wine.


      PubDate: 2015-07-01T17:31:31Z
       
  • Quantifying strain variability in modeling growth of Listeria
           monocytogenes
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): D.C. Aryani , H.M.W. den Besten , W.C. Hazeleger , M.H. Zwietering
      Prediction of microbial growth kinetics can differ from the actual behavior of the target microorganisms. In the present study, the impact of strain variability on maximum specific growth rate (μ max) (h−1) was quantified using twenty Listeria monocytogenes strains. The μ max was determined as function of four different variables, namely pH, water activity (aw)/NaCl concentration [NaCl], undissociated lactic acid concentration ([HA]), and temperature (T). The strain variability was compared to biological and experimental variabilities to determine their importance. The experiment was done in duplicate at the same time to quantify experimental variability and reproduced at least twice on different experimental days to quantify biological (reproduction) variability. For all variables, experimental variability was clearly lower than biological variability and strain variability; and remarkably, biological variability was similar to strain variability. Strain variability in cardinal growth parameters, namely pHmin, [NaCl]max, [HA]max, and Tmin was further investigated by fitting secondary growth models to the μ max data, including a modified secondary pH model. The fitting results showed that L. monocytogenes had an average pHmin of 4.5 (5–95% prediction interval (PI) 4.4–4.7), [NaCl]max of 2.0mM (PI 1.8–2.1), [HA]max of 5.1mM (PI 4.2–5.9), and Tmin of −2.2°C (PI (−3.3)–(−1.1)). The strain variability in cardinal growth parameters was benchmarked to available literature data, showing that the effect of strain variability explained around 1/3 or less of the variability found in literature. The cardinal growth parameters and their prediction intervals were used as input to illustrate the effect of strain variability on the growth of L. monocytogenes in food products with various characteristics, resulting in 2–4 logCFU/ml(g) difference in growth prediction between the most and least robust strains, depending on the type of food product. This underlined the importance to obtain quantitative knowledge on variability factors to realistically predict the microbial growth kinetics.


      PubDate: 2015-07-01T17:31:31Z
       
  • Microbiological analysis of pre-packed sweet basil (Ocimum basilicum) and
           coriander (Coriandrum sativum) leaves for the presence of Salmonella spp.
           and Shiga toxin-producing E. coli
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Stefanie Delbeke , Siele Ceuppens , Liesbeth Jacxsens , Mieke Uyttendaele
      Enteric pathogens, such as Salmonella spp. and pathogenic Escherichia coli, have been detected and associated with food borne outbreaks from (imported) fresh leafy herbs. Screening on imported herbs from South East Asian countries has been described. However, limited information on prevalence of these pathogens is available from other sourcing regions. Therefore, fresh pre-packed basil and coriander leaves from a Belgian trading company were investigated for the presence of Salmonella spp., Shiga toxin-producing E. coli (STEC), generic E. coli and coliforms. In total 592 samples were collected originating from Belgium, Israel and Cyprus during 2013–2014. Multiplex PCR followed by further culture confirmation was used for the detection of Salmonella spp. and STEC, whereas the Petrifilm Select E. coli and VRBL-agar were used, respectively, for the enumeration of E. coli and coliforms. Salmonella was detected in 10 out of 592 samples (25g) (1.7%; 5 from basil and 5 from coriander), of which two samples were sourced from Israel and eight from Cyprus. The presence of STEC was suspected in 11 out of 592 samples (25g) (1.9%; 3 basil and 8 coriander), due to the detection of stx and eae genes, of which one sample originated from Belgium, four from Israel and six from Cyprus. No STEC was isolated by culture techniques, but in three samples a serotype (O26, O103 or O111) with its most likely associated eae-variant (β or θ) was detected by PCR. Generic E. coli was enumerated in 108 out of 592 samples, whereby 55, 32 and 13 samples respectively between 10–100, 100–1000 and 1000–10,000cfu/g and 8 samples exceeding 10,000cfu/g. Coliforms were enumerated in all herb samples at variable levels ranging from 1.6 to 7.5logcfu/g. Further statistics indicate that the E. coli class (categorized by level) was significantly correlated with the presence of Salmonella (p<0.001) or STEC (p=0.019), while coliform counts were significant correlated with Salmonella (p<0.001), but not with STEC (p=0.405). Generic E. coli class is a better indicator for the presence of enteric pathogens than coliforms on fresh herbs, but the relationship between E. coli and Salmonella or STEC was not strong enough to provide a threshold value for E. coli to assure food safety (i.e. no pathogens present). Results indicate that fresh leafy herbs like basil and coriander sourced from different cultivation regions, may contain enteric pathogens and potentially pose a risk for human health.


      PubDate: 2015-07-01T17:31:31Z
       
  • Diversity of black Aspergilli isolated from raisins in Argentina:
           Polyphasic approach to species identification and development of SCAR
           markers for Aspergillus ibericus
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): G. Giaj Merlera , S. Muñoz , I. Coelho , L.R. Cavaglieri , A.M. Torres , M.M. Reynoso
      Aspergillus section Nigri is a heterogeneous fungal group including some ochratoxin A producer species that usually contaminate raisins. The section contains the Series Carbonaria which includes the toxigenic species Aspergillus carbonarius and nontoxigenic Aspergillus ibericus that are phenotypically undistinguishable. The aim of this study was to examine the diversity of black aspergilli isolated from raisins and to develop a specific genetic marker to distinguish A. ibericus from A. carbonarius. The species most frequently found in raisins in this study were Aspergillus tubingensis (35.4%) and A. carbonarius (32.3%), followed by Aspergillus luchuensis (10.7%), Aspergillus japonicus (7.7%), Aspergillus niger (6.2%), Aspergillus welwitschiae (4.6%) and A. ibericus (3.1%). Based on inter-simple sequence repeat (ISSR) fingerprinting profiles of major Aspergillus section Nigri members, a sequence-characterized amplified region (SCAR) marker was identified. Primers were designed based on the conserved regions of the SCAR marker and were utilized in a PCR for simultaneous identification of A. carbonarius and A. ibericus. The detection level of the SCAR-PCR was found to be 0.01ng of purified DNA. The present SCAR-PCR is rapid and less cumbersome than conventional identification techniques and could be a supplementary strategy and a reliable tool for high-throughput sample analysis.


      PubDate: 2015-07-01T17:31:31Z
       
  • Editorial Board
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208




      PubDate: 2015-07-01T17:31:31Z
       
  • Combined effect of chilling and desiccation on survival of Escherichia
           coli suggests a transient loss of culturability
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): L.A. Mellefont , C. Kocharunchitt , T. Ross
      Dry air carcass chilling regimes used in some Australian meat works, which not only rapidly reduce the temperature of the carcasses but also dry the meat surface initially, are reported to cause reductions in the number of Escherichia coli present on carcasses after processing. This study used a laboratory broth model system to systematically investigate the basis of such reductions by simulating chilling and desiccation profiles observed on carcasses separately and, finally, in combination. Observed growth was compared to the predictions generated by a strain-specific modification of a validated E. coli growth model (Mellefont et al., 2003; Performance evaluation of a model describing the effects of temperature, water activity, pH and lactic acid concentration on the growth of E. coli). Good agreement between observed and predicted growth was evident when chilling or desiccation profiles were simulated individually. However, when chilling and desiccation profiles were applied simultaneously the observed population kinetics deviated from those predicted by the model. An initial reduction in cell numbers, not predicted by the model, was observed followed by an anomalously rapid increase in population density before growth resumed at a rate expected for the conditions imposed. From our analysis of the kinetics of the population changes, we suggest that the initial decrease in cell numbers was unlikely due to cell death, because conditions were growth permissive. Considering all possible explanations from the observed population kinetics, we propose that a temporary loss of the ability to produce colonies on agar plates may occur. These results may explain reports of increases in E. coli numbers two to three days after commencement of chilling, compared to those observed after 16–24h, despite the imposition of growth-preventing temperatures.


      PubDate: 2015-07-01T17:31:31Z
       
  • Microbiological survey of raw and ready-to-eat leafy green vegetables
           marketed in Italy
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): M.N. Losio , E. Pavoni , S. Bilei , B. Bertasi , D. Bove , F. Capuano , S. Farneti , G. Blasi , D. Comin , C. Cardamone , L. Decastelli , E. Delibato , P. De Santis , S. Di Pasquale , A. Gattuso , E. Goffredo , A. Fadda , M. Pisanu , D. De Medici
      The presence of foodborne pathogens (Salmonella spp., Listeria monocytogenes, Escherichia coli O157:H7, thermotolerant Campylobacter, Yersinia enterocolitica and norovirus) in fresh leafy (FL) and ready-to-eat (RTE) vegetable products, sampled at random on the Italian market, was investigated to evaluate the level of risk to consumers. Nine regional laboratories, representing 18 of the 20 regions of Italy and in which 97.7% of the country's population resides, were involved in this study. All laboratories used the same sampling procedures and analytical methods. The vegetable samples were screened using validated real-time PCR (RT-PCR) methods and standardized reference ISO culturing methods. The results show that 3.7% of 1372 fresh leafy vegetable products and 1.8% of 1160 “fresh-cut” or “ready-to-eat” (RTE) vegetable retailed in supermarkets or farm markets, were contaminated with one or more foodborne pathogens harmful to human health.


      PubDate: 2015-07-01T17:31:31Z
       
  • Reduction of Salmonella enterica on the surface of eggshells by sequential
           treatment with aqueous chlorine dioxide and drying
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Seonyeong Choi , Sunhyung Park , Yoonsook Kim , Byeong-sam Kim , Larry R. Beuchat , Kim Hoikyung , Jee-Hoon Ryu
      The synergistic effects of sequential treatments with chlorine dioxide (ClO2) and drying in killing Salmonella enterica on the surface of chicken eggshells were investigated. Initial experiments were focused on comparing lethalities of sodium hypochlorite (NaOCl) and ClO2. Eggs surface-inoculated with S. enterica in chicken feces as a carrier were immersed in water, NaOCl (50 or 200μg/mL), or ClO2 (50 or 200μg/mL) for 1 or 5min. For 1-min treatments, lethal activities of sanitizers were not significantly different (P >0.05). However, after treatment with ClO2 for 5min, reductions of S. enterica were significantly greater (P ≤0.05) than reductions after treatment with water or NaOCl. The effect of treatment of eggs with ClO2 or NaOCl, followed by drying at 43% relative humidity and 25°C for 24 and 48h, were determined. Populations of S. enterica decreased during drying, regardless of the type of sanitizer treatment. ClO2 treatment, compared to water or NaOCl treatments, resulted in additional reductions of ca. >1.3logCFU/egg during drying. This indicates that sequential treatments with ClO2 and drying induced synergistic lethal effects against S. enterica on the surface of eggshells. These observations will be useful when selecting a sanitizer to control S. enterica on the surface of eggshells and designing an effective egg sanitization system exploiting the synergistic lethal effects of sanitizer and drying.


      PubDate: 2015-07-01T17:31:31Z
       
  • Fate of Alicyclobacillus spp. in enrichment broth and in juice
           concentrates
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Juan Martin Oteiza , Silvina Soto , Verônica O. Alvarenga , Anderson S. Sant'Ana , Leda Gianuzzi
      In this study, the fate of Alicyclobacillus acidoterrestris spores in different types of juice concentrates stored under different conditions was investigated. In addition, the impact of dilution procedures during the enrichment step for the detection of Alicyclobacillus in lemon juice concentrates was studied. Pear, red grape, mango, tangerine, carrot and lemon juice concentrates (50–69.4°Brix, pH1.7–4.3) were inoculated with A. acidoterrestris spores (103 spore/mL) and stored at 4°C and 20°C, after which the spores were counted at 0, 2, 5, 9, 17, 21, 28, 36, 43, and 50days. No significant differences in the number of Alicyclobacillus spores were observed at storage temperatures of 4°C and 20°C (p>0.05). The results also indicated that the number of spores of A. acidoterrestris remained stable in all types of juice concentrates during the storage period, except in lemon juice concentrate. In lemon juice concentrate, a decline in A. acidoterrestris spore populations of 0.3–0.8logCFU/mL was observed within 5–10days of storage. The decline in A. acidoterrestris spore populations was more pronounced in cloudy lemon juice concentrate, which contained higher concentrations of flavonoids (mainly eriocitrin and hesperidin) than clarified lemon juice concentrate. It was also found that dilution of lemon juice concentrate samples in the proportion of 1:19 allowed the germination of A. acidoterrestris spores and the growth of populations of up to 107 CFU/mL. In contrast, the proportion (1:9) recommended in internationally recognized methods led to a reduction in the population of this microorganism that would yield false negative results. Data presented in this study demonstrated that Alicyclobacillus spores remain stable in most juice concentrates during storage, but that natural antimicrobial compounds present in some of them may decrease spore counts and inhibit their recovery by detection procedures.


      PubDate: 2015-07-01T17:31:31Z
       
  • Quantitative distribution of Salmonella spp. and Escherichia coli on beef
           carcasses and raw beef at retail establishments
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): L. Martínez-Chávez , E. Cabrera-Diaz , J.A. Pérez-Montaño , L.E. Garay-Martínez , J.J. Varela-Hernández , A. Castillo , L. Lucia , M.G. Ávila-Novoa , M.A. Cardona-López , P. Gutiérrez-González , N.E. Martínez-Gonzáles
      Salmonella is a foodborne pathogen that commonly inhabits the gastrointestinal tract of a healthy feedlot cattle and can be transferred to the carcass surface during hide removal and evisceration procedures. Numerous investigations on Salmonella prevalence throughout different stages of the beef chain have been conducted. In contrast, limited studies are available on quantitative determinations of Salmonella at different steps in raw meat production. Quantitative data, particularly for pathogenic bacteria such as Salmonella are important for quantitative risk assessment. Salmonella spp. and Escherichia coli populations were enumerated on beef carcass samples collected at abattoirs and also in beef chunks and ground beef samples collected from butcher's shops at retail in Jalisco State, Mexico. Sponge samples from beef carcass sides (n=142) were collected immediately after final water wash and before chilling at three non-federally inspected abattoirs following USDA-FSIS sampling protocols. Beef chunks (n=84) and ground beef (n=65) samples were obtained from 86 butcher's shops. Salmonella enumeration was conducted by the Most Probable Number method and E. coli counts were determined using Petrifilm plates. Salmonella was isolated from 18% of beef carcasses, 39% of beef chunks and 71% of ground beef samples. Salmonella mean counts were 1.3±0.9LogMPN/300cm2 on beef carcasses, 1.9±0.9 and 2.3±1.1LogMPN/25g in beef chunks and ground beef samples, respectively. Twenty-six Salmonella serotypes and 11 serogroups were identified among 432 isolates recovered. Salmonella typhimurium (14%), Salmonella sinstorf (12%) and S. Group E1 monophasic (10%) were the most frequent. Escherichia coli was present on 97, 84 and 100% of beef carcasses, beef chunks and ground beef samples, respectively. Escherichia coli mean counts were 3.2±0.7LogCFU/300cm2, 3.9±1.1 and 4.5±1.2LogCFU/25g on beef carcasses, beef chunks and ground beef, respectively. Salmonella prevalence and mean counts found in raw beef were higher than previously reported in studies from other countries. The data collected in this study show a trend in the prevalence of Salmonella to be higher as meat processing is extended at retail. This, together with the diversity of serotypes found, indicates that raw meat is exposed to multiple contamination sources during slaughter and retail processing and highlights the necessity to implement Sanitation Standard Operating Procedures for those establishments. Finally, this study provides quantitative information for future risk assessments associated with the risk of human salmonellosis.


      PubDate: 2015-07-01T17:31:31Z
       
  • DNA-based methodologies for the quantification of live and dead cells in
           formulated biocontrol products based on Pantoea agglomerans CPA-2
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Lourdes Soto-Muñoz , Rosario Torres , Josep Usall , Inmaculada Viñas , Cristina Solsona , Neus Teixidó
      Pantoea agglomerans strain CPA-2 is an effective biocontrol agent (BCA) against the major postharvest pathogens present on pome and citrus fruits. Dehydration, such as freeze-drying, spray-drying and fluidized bed drying is one of the best ways to formulate BCAs. In this work, the survival of CPA-2 cells after formulation was determined by dilution plating and molecular methods as qPCR alone and combined with a sample pretreatment with a propidium monoazide dye (PMA-qPCR) and they were used to calculate treatment concentrations in efficacy trials on postharvest oranges. Furthermore, no significant differences in CPA-2 survival were observed as determined by dilution plating and PMA-qPCR after both the freeze drying and fluidized bed drying processes; however, an interesting significant difference was observed in the spray dried product comparing all quantitative methods. A difference of 0.48 and 2.17log10 CFU or cellsg/dw was observed among PMA-qPCR with qPCR and dilution plating, respectively. According to our study, dilution plating was shown to be an unreliable tool for monitoring the survival of CPA-2 after spray drying. In contrast, the combination of PMA and qPCR enabled a quick and unequivocal methodology to enumerate viable and VBNC CPA-2 cells under stress-dried conditions. Efficacy trials showed that, after 3days, spray drying formulation rehydrated with 10% non-fat skimmed milk (NFSM) was as effective as fresh cells to control Penicillium digitatum in oranges.


      PubDate: 2015-07-01T17:31:31Z
       
  • Risk assessment of proteolytic Clostridium botulinum in canned foie gras
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Jeanne-Marie Membré , Moctar Diao , Chantal Thorin , Grégoire Cordier , François Zuber , Stéphane André
      In this study, a risk assessment of proteolytic Clostridium botulinum in canned foie gras was performed, the number of illnesses per year in France due to C. botulinum in foie gras was estimated. Data on initial level in raw materials were collected at manufacturers and analysed using a Negative Binomial distribution. The effect of the usual foie gras heat treatment (equivalent time at 121°C: F0 =0.5min) was considered at two levels: first, it led to an inactivation (estimated to 2.3 log); second it led to a spore injury and then to a spore inhibition. This latter effect was assessed by analysing data from a challenge test study carried out with Clostridium sporogenes spores in the foie gras product. The probability of spore recovering after thermal inhibition was estimated to 9.5×10−8 (corresponding to 7.0 log). The data on the consumption pattern were collected on the French market. The Quantitative Microbiological Risk Assessment (QMRA) model and all the assumptions are reported in detail in the study. The initial contamination of raw materials, effect of thermal treatment on microbial inactivation and spore inhibition were handled mathematically using a probabilistic framework, considering only the variability dimension. The model was implemented in Excel and run through Monte Carlo simulation, using @Risk software. In parallel, epidemiological data collected from the French Institute for Public Health Surveillance during the period 2001–2012 were used to estimate an Appropriate Level Of Protection (ALOP) and then a Food Safety Objective (FSO): ALOP equalled to 2.5×10−3 illnesses per million inhabitant per year, FSO equalled to 1.4×10−9 foie gras portions containing C. botulinum spore (expressed in decimal logarithm, FSO=−8.9). The QMRA model output values were smaller, but on the same order of magnitude as these two figures: 8.0×10−4 illnesses per million inhabitants per year, and, 4.5×10−10 (−9.3 log) foie gras portions containing C. botulinum spores able to recover. It was then possible to conclude that the current practices regarding thermal treatment of canned foie gras are sufficient to control the risk of C. botulinum in foie gras in France.


      PubDate: 2015-07-01T17:31:31Z
       
  • Cold plasma inactivation of internalised bacteria and biofilms for
           Salmonella enterica serovar Typhimurium, Listeria monocytogenes and
           Escherichia coli
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Dana Ziuzina , Lu Han , Patrick J. Cullen , Paula Bourke
      Microbial biofilms and bacteria internalised in produce tissue may reduce the effectiveness of decontamination methods. In this study, the inactivation efficacy of in-package atmospheric cold plasma (ACP) afterglow was investigated against Salmonella Typhimurium, Listeria monocytogenes and Escherichia coli in the forms of planktonic cultures, biofilms formed on lettuce and associated bacteria internalised in lettuce tissue. Prepared lettuce broth (3%) was inoculated with bacteria resulting in a final concentration of ~7.0log10 CFU/ml. For biofilm formation and internalisation, lettuce pieces (5×5cm) were dip-inoculated in bacterial suspension of ~7.0log10 CFU/ml for 2h and further incubated for 0, 24 and 48h at either 4°C or room temperature (~22°C) in combination with light/dark photoperiod or at 4°C under dark conditions. Inoculated samples were sealed inside a rigid polypropylene container and indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (80kVRMS) air ACP with subsequent storage for 24h at 4°C. ACP treatment for 30s reduced planktonic populations of Salmonella, L. monocytogenes and E. coli suspended in lettuce broth to undetectable levels. Depending on storage conditions, bacterial type and age of biofilm, 300s of treatment resulted in reduction of biofilm populations on lettuce by a maximum of 5log10 CFU/sample. Scanning electron and confocal laser microscopy pointed to the incidence of bacterial internalisation and biofilm formation, which influenced the inactivation efficacy of ACP. Measured intracellular reactive oxygen species (ROS) revealed that the presence of organic matter in the bacterial suspension might present a protective effect against the action of ROS on bacterial cells. This study demonstrated that high voltage in-package ACP could be a potential technology to overcome bacterial challenges associated with food produce. However, the existence of biofilms and internalised bacteria should be considered for further optimisation of ACP treatment parameters in order to achieve an effective control of the realistic challenges posed by foodborne pathogens.


      PubDate: 2015-07-01T17:31:31Z
       
  • Cracking Streptococcus thermophilus to stimulate the growth of the
           probiotic Lactobacillus casei in co-culture
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Chengjie Ma , Aimin Ma , Guangyu Gong , Zhenmin Liu , Zhengjun Wu , Benheng Guo , Zhengjun Chen
      Lactobacillus casei, a probiotic, and Streptococcus thermophilus, a fast acidifying lactic acid bacterial strain, are both used in the food industry. The aim of this study was to investigate the interaction between L. casei and S. thermophilus in the presence or absence of S. thermophilus-specific bacteriophage during milk fermentation. The acidification capability of L. casei co-cultured with S. thermophilus was significantly higher than that observed for L. casei or S. thermophilus cultured alone. However, the probiotic content (i.e., L. casei cell viability) was low. The fastest acidification and the highest viable L. casei cell count were observed in co-cultures of L. casei and S. thermophilus with S. thermophilus phage. In these co-cultures, S. thermophilus compensated for the slow acid production of L. casei in the early exponential growth phase. Thereafter, phage-induced lysis of the S. thermophilus cells eliminated the competition for nutrients, allowing L. casei to grow well. Additionally, the ruptured S. thermophilus cells released intracellular factors, which further promoted the growth and function of the probiotic bacteria. Crude cellular extract isolated from S. thermophilus also significantly accelerated the growth and propagation of L. casei, supporting the stimulatory role of the phage on this micro-ecosystem.


      PubDate: 2015-07-01T17:31:31Z
       
  • Prevalence of antimicrobial resistance of non-typhoidal Salmonella
           serovars in retail aquaculture products
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Jianmin Zhang , Xiaowei Yang , Dai Kuang , Xianming Shi , Wenjia Xiao , Jing Zhang , Zhen Gu , Xuebin Xu , Jianghong Meng
      Aquaculture products can become sources of Salmonella by exposure to contaminated water or through processing practices, thus representing a public health hazard. A study was conducted on Salmonella contamination in aquaculture products sampled from marketplaces and retailers in Shanghai, China. A total of 730 samples (including fish, shellfish, bullfrog, clam, shrimp and others) were obtained from 2006 to 2011. Among them, 217 (29.7%) were positive for Salmonella. Thirty-eight serovars were identified in the 217 Salmonella isolates. The most prevalent were Salmonella Aberdeen (18.4%), S. Wandsworth (12.0%), S. Thompson (9.2%), S. Singapore (5.5%), S. Stanley (4.6%), S. Schwarzengrund (4.6%), S. Hvittingfoss (4.1%) and S. Typhimurium (4.1%). Many resistant isolates were detected, with 69.6% resistant to at least one antimicrobial drug. We observed high resistance to sulfonamides (56.5%), tetracycline (34.1%), streptomycin (28.6%), ampicillin (23.5%) and nalidixic acid (21.2%). Lower levels of resistance were found for gentamicin (3.2%), ciprofloxacin (2.3%), ceftiofur (1.3%), cefotaxime (0.9%), ceftazidime (0.5%) and cefepime (0.5%). A total of 43.3% of the Salmonella isolates were multidrug-resistant and 44 different resistance patterns were found. This study provided data on the prevalence, serovars and antimicrobial resistance of Salmonella from retail aquaculture products in Shanghai, and indicated the need for monitoring programs for microbiologic safety in such projects and for more prudent drug use in aquaculture production in order to reduce the risk of development and spread of antimicrobial resistance.


      PubDate: 2015-07-01T17:31:31Z
       
  • Antimicrobial activity of thyme oil co-nanoemulsified with sodium
           caseinate and lecithin
    • Abstract: Publication date: 1 October 2015
      Source:International Journal of Food Microbiology, Volume 210
      Author(s): Jia Xue , P. Michael Davidson , Qixin Zhong
      Emulsions of essential oils are investigated as potential intervention strategies to improve food safety and are preferably prepared from generally-recognized-as-safe emulsifiers. Stable thyme oil nanoemulsions can be prepared using combinations of sodium caseinate (NaCas) and soy lecithin. The objective of the present research was to study the antimicrobial activity of these nanoemulsions and understand the impacts of emulsifier concentrations. 10g/L thyme oil was emulsified using combinations of (A) 4% w/v NaCas and 0.5% w/v lecithin or (B) 2% w/v NaCas and 0.25% w/v lecithin by high shear homogenization. Combination A resulted in a transparent emulsion with a mean droplet diameter of 82.5nm, while it was turbid for the Combination B with an average diameter of 125.5nm. Nanoemulsified thyme oil exhibited quicker initial reductions of bacteria than free thyme oil in tryptic soy broth (TSB) and 2% reduced fat milk at 21°C, due to the improved dispersibility of thyme oil. In TSB with 0.3g/L thyme oil, it took less than 4 and 8h for two nanoemulsions and free oil, respectively, to reduce Escherichia coli O157:H7 and Listeria monocytogenes to be below the detection limit. The emulsified thyme oil also demonstrated more significant reductions of bacteria initially (4 and 8h) in 2% reduced fat milk than free thyme oil. Especially, with 4g/L thyme oil, the nanoemulsion prepared with Combination A reduced L. monocytogenes to be below the detection limit after 72h, while the free thyme oil treatment was only bacteriostatic and the turbid nanoemulsion treatment with Combination B resulted in about 1logCFU/mL reduction. However, E. coli O157:H7 treated with 3g/L emulsified thyme oil and Salmonella Enteritidis treated with 4g/L emulsified thyme oil recovered to a higher extent in milk than free thyme oil treatments. The increased concentration of emulsifiers in Combination A apparently reduced the antimicrobials available to alter bacteria membrane permeability as tested by the crystal violet assay at low antimicrobial concentrations and short time (1h). The findings suggest that nanoemulsions can be potentially used to incorporate thyme oil for use as antimicrobial preservatives in foods.


      PubDate: 2015-07-01T17:31:31Z
       
  • Methodology for modeling the disinfection efficiency of fresh-cut leafy
           
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): S. Van Haute , F. López-Gálvez , V.M. Gómez-López , Markus Eriksson , F. Devlieghere , Ana Allende , I. Sampers
      A methodology to i) assess the feasibility of water disinfection in fresh-cut leafy greens wash water and ii) to compare the disinfectant efficiency of water disinfectants was defined and applied for a combination of peracetic acid (PAA) and lactic acid (LA) and comparison with free chlorine was made. Standardized process water, a watery suspension of iceberg lettuce, was used for the experiments. First, the combination of PAA+LA was evaluated for water recycling. In this case disinfectant was added to standardized process water inoculated with Escherichia coli (E. coli) O157 (6logCFU/mL). Regression models were constructed based on the batch inactivation data and validated in industrial process water obtained from fresh-cut leafy green processing plants. The UV254(F) was the best indicator for PAA decay and as such for the E. coli O157 inactivation with PAA+LA. The disinfection efficiency of PAA+LA increased with decreasing pH. Furthermore, PAA+LA efficacy was assessed as a process water disinfectant to be used within the washing tank, using a dynamic washing process with continuous influx of E. coli O157 and organic matter in the washing tank. The process water contamination in the dynamic process was adequately estimated by the developed model that assumed that knowledge of the disinfectant residual was sufficient to estimate the microbial contamination, regardless the physicochemical load. Based on the obtained results, PAA+LA seems to be better suited than chlorine for disinfecting process wash water with a high organic load but a higher disinfectant residual is necessary due to the slower E. coli O157 inactivation kinetics when compared to chlorine.


      PubDate: 2015-07-01T17:31:31Z
       
  • Temporal patterns of Campylobacter contamination on chicken and their
           relationship to campylobacteriosis cases in the United States
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Michael S. Williams , Neal J. Golden , Eric D. Ebel , Emily T. Crarey , Heather P. Tate
      The proportion of Campylobacter contaminated food and water samples collected by different surveillance systems often exhibit seasonal patterns. In addition, the incidence of foodborne campylobacteriosis also tends to exhibit strong seasonal patterns. Of the various product classes, the occurrence of Campylobacter contamination can be high on raw poultry products, and chicken is often thought to be one of the leading food vehicles for campylobacteriosis. Two different federal agencies in the United States collected samples of raw chicken products and tested them for the presence of Campylobacter. During the same time period, a consortium of federal and state agencies operated a nationwide surveillance system to monitor cases of campylobacteriosis in the United States. This study uses a common modeling approach to estimate trends and seasonal patterns in both the proportion of raw chicken product samples that test positive for Campylobacter and cases of campylobacteriosis. The results generally support the hypothesis of a weak seasonal increase in the proportion of Campylobacter positive chicken samples in the summer months, though the number of Campylobacter on test-positive samples is slightly lower during this time period. In contrast, campylobacteriosis cases exhibit a strong seasonal pattern that generally precedes increases in contaminated raw chicken. These results suggest that while contaminated chicken products may be responsible for a substantial number of campylobacteriosis cases, they are most likely not the primary driver of the seasonal pattern in human illness.


      PubDate: 2015-07-01T17:31:31Z
       
  • Fermentation of table olives by oleuropeinolytic starter culture in
           reduced salt brines and inactivation of Escherichia coli O157:H7 and
           Listeria monocytogenes
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): M. Tataridou , P. Kotzekidou
      The effect of an autochthonous starter culture developed by oleuropeinolytic strains belonging to the Lactobacillus plantarum group on the physicochemical and microbiological characteristics and the biophenol content of table olives fermented under reduced salt conditions was studied. Black (cv. Kalamata) and green (cv. Chalkidikis) olives were fermented in two different kinds of brine (Brine A containing 2.3% NaCl, 32.3mM Ca-acetate and 33.9mM Ca-lactate and Brine B containing 4% NaCl, pH5.0 in both brines). The sensory attributes of olives fermented by oleuropeinolytic starter culture assessed by a trained panel did not differ significantly compared with industrial processing. It is possible to carry out significant changes in table olive processing applying a completely microbiological procedure using oleuropeinolytic strains of the L. plantarum group as both the debittering and the fermentation agent in order to achieve improved sensorial and nutritional characteristics of the final product. Table olives processed by the suggested methodology may constitute a good source of biophenols in the diet, especially hydroxytyrosol and tyrosol. The inactivation potential of Escherichia coli O157 EDL-932 and Listeria monocytogenes Scott A in olives fermented by oleuropeinolytic starter culture was evaluated. The population of each pathogen in olive homogenates of both cultivars is inactivated by more than 6logCFU/ml in less than 24h. When whole fermented olives were submerged in peptone/saline (containing 6.7logCFU/ml of the relevant bacterial pathogen) for 30min followed by rinsing in distilled water, the population of viable foodborne pathogens dropped more than 4 logs in olive pulp. During subsequent storage at 22 or 4°C the population of L. monocytogenes Scott A was further eliminated under the detection limit in both olive cultivars whereas the population of E. coli O157 EDL-932 could be detected in olives stored in peptone/saline at 22°C for 7days. The inhibitory effect of olives fermented by oleuropeinolytic starter culture in reduced salt brines on pathogens is due to the antimicrobial activity of the phenolic compounds and the antagonistic action of the associated microflora.


      PubDate: 2015-07-01T17:31:31Z
       
  • Functional csdA is needed for effective adaptation and initiation of
           growth of Clostridium botulinum ATCC 3502 at suboptimal temperature
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208
      Author(s): Henna Söderholm , Yağmur Derman , Miia Lindström , Hannu Korkeala
      The activity of RNA helicase csdA (cbo2802) after temperature downshift was compared to its activity at optimal growth temperature, and the effect of sense and antisense oriented insertional inactivation of cbo2802 on the growth of ATCC 3502 at suboptimal temperature was evaluated. The relative cbo2802 transcript level was significantly induced for 30min to 5h after cold shock. In contrast, a significant decrease in the relative transcript level of cbo2802 was observed within the same time frame at 37°C. Inactivation of cbo2802 led to an extensive delay in initiation of exponential growth at 20°C but not at 37°C. In addition, the mean minimum growth temperatures of the mutant strains were higher than those of the wild-type strain. During a 24-hour incubation at 37°C, all strains were motile, whereas at 20°C the mutant strains showed severely impaired motility compared to the wild-type strain. This study shows that a functional csdA is needed for effective adaptation and initiation of growth and motility of Clostridium botulinum ATCC 3502 at suboptimal temperature.


      PubDate: 2015-07-01T17:31:31Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 2 September 2015
      Source:International Journal of Food Microbiology, Volume 208




      PubDate: 2015-07-01T17:31:31Z
       
  • Editorial Board
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207




      PubDate: 2015-07-01T17:31:31Z
       
  • A systematic review of studies on Escherichia coli and Enterobacteriaceae
           on beef carcasses at the slaughterhouse
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Lisa Barco , Simone Belluco , Anna Roccato , Antonia Ricci
      European legislation has defined as process hygiene criteria for the main livestock species (cattle, sheep, goats, horses and pigs) the monitoring of aerobic colony count and Enterobacteriaceae. Detected values above the defined criteria require an improvement in slaughter hygiene and the review of process control. The main source of microbiological contamination of beef carcasses along the slaughterline is of fecal origin, therefore Escherichia coli and Enterobacteriaceae seem to be the most suitable indicators to assess the hygienic status of the slaughter process. Although microbiological criteria addressing indicator bacteria have been in place in industrialized countries for several years, scattered information still exists on factors affecting their counts on beef carcasses along the slaughterline. Therefore, a systematic literature review, covering the period 2000–2012, was conducted to gather information concerning: 1) counts of E. coli and Enterobacteriaceae on beef carcasses linked to different stages of the slaughterline; 2) factors influencing presence/counts of E. coli and Enterobacteriaceae on beef carcasses; and 3) the relationship between indicator bacteria (E. coli and Enterobacteriaceae) counts and visual fecal contamination of beef carcasses. According to the 41 retrieved papers the following conclusions were drawn. A decrease of the indicator bacteria counts was recorded after sequential decontamination treatments, such as pasteurization and hot water washing. Slaughterhouse characteristics influenced bacterial load of beef carcasses, although it was difficult to assess which factors (i.e., slaughterhouse throughput, design of the plant, surveillance system in place) had the greatest effect. Finally, carcasses from fecal contaminated animals had higher bacterial loads than those from clean animals. Therefore, the development of a visual classification system of the level of dirtiness of carcasses and the application of effective treatments on the carcasses classified as dirty along the slaughterline can lead to a contamination level for these carcasses comparable to or lower than that of originally clean ones at the end of the slaughterline.


      PubDate: 2015-07-01T17:31:31Z
       
  • Potential of lactic acid bacteria in aflatoxin risk mitigation
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Sara H. Ahlberg , Vesa Joutsjoki , Hannu J. Korhonen
      Aflatoxins (AF) are ubiquitous mycotoxins contaminating food and feed. Consumption of contaminated food and feed can cause a severe health risk to humans and animals. A novel biological method could reduce the health risks of aflatoxins through inhibiting mold growth and binding aflatoxins. Lactic acid bacteria (LAB) are commonly used in fermented food production. LAB are known to inhibit mold growth and, to some extent, to bind aflatoxins in different matrices. Reduced mold growth and aflatoxin production may be caused by competition for nutrients between bacterial cells and fungi. Most likely, binding of aflatoxins depends on environmental conditions and is strain-specific. Killed bacteria cells possess consistently better binding abilities for aflatoxin B1 (AFB1) than viable cells. Lactobacilli especially are relatively well studied and provide noticeable possibilities in binding of aflatoxin B1 and M1 in food. It seems that binding is reversible and that bound aflatoxins are released later on (Haskard et al., 2001; Peltonen et al., 2001). This literature review suggests that novel biological methods, such as lactic acid bacteria, show potential in mitigating toxic effects of aflatoxins in food and feed.


      PubDate: 2015-07-01T17:31:31Z
       
  • Reduction of Salmonella on chicken meat and chicken skin by combined or
           sequential application of lytic bacteriophage with chemical antimicrobials
           
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Anuraj T. Sukumaran , Rama Nannapaneni , Aaron Kiess , Chander Shekhar Sharma
      The effectiveness of recently approved Salmonella lytic bacteriophage preparation (SalmoFresh™) in reducing Salmonella in vitro and on chicken breast fillets was examined in combination with lauric arginate (LAE) or cetylpyridinium chloride (CPC). In another experiment, a sequential spray application of this bacteriophage (phage) solution on Salmonella inoculated chicken skin after a 20s dip in chemical antimicrobials (LAE, CPC, peracetic acid, or chlorine) was also examined in reducing Salmonella counts on chicken skin. The application of phage in combination with CPC or LAE reduced S. Typhimurium, S. Heidelberg, and S. Enteritidis up to 5 log units in vitro at 4°C. On chicken breast fillets, phage in combination with CPC or LAE resulted in significant (p<0.05) reductions of Salmonella ranging from 0.5 to 1.3logCFU/g as compared to control up to 7days of refrigerated storage. When phage was applied sequentially with chemical antimicrobials, all the treatments resulted in significant reductions of Salmonella. The application of chlorine (30ppm) and PAA (400ppm) followed by phage spray (109 PFU/ml) resulted in highest Salmonella reductions of 1.6–1.7 and 2.2–2.5logCFU/cm2, respectively. In conclusion, the surface applications of phage in combination with LAE or CPC significantly reduced Salmonella counts on chicken breast fillets. However, higher reductions in Salmonella counts were achieved on chicken skin by the sequential application of chemical antimicrobials followed by phage spray. The sequential application of chlorine, PAA, and phage can provide additional hurdles to reduce Salmonella on fresh poultry carcasses or cut up parts.


      PubDate: 2015-07-01T17:31:31Z
       
  • Activation of the chromosomally encoded mazEFBif locus of Bifidobacterium
           longum under acid stress
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Yan-Xia Wei , Lu Ye , Dian-Bin Liu , Zhuo-Yang Zhang , Chang Liu , Xiao-Kui Guo
      Toxin–antitoxin (TA) systems are distributed within the genomes of almost all free-living bacteria. Although the roles of chromosomally encoded TA systems are still under debate, they are suspected to be involved in various stress responses. Here, we provide the first report of a type II TA system in the probiotic bacterium Bifidobacterium longum. Bioinformatic analysis of the B. longum JDM301 genome identified a pair of linked genes encoding a MazEF-like TA system at the locus BLJ_811–BLJ_812. Our results showed that B. longum mazEF Bif genes form a bicistronic operon. The over-expression of MazFBif was toxic to Escherichia coli and could be neutralized by the co-expression of its cognate antitoxin MazEBif. We demonstrated that MazEFBif was activated during acid stress, which would most likely be encountered in the gastrointestinal tract. In addition, we found that the protease ClpPXBif, in addition to MazEFBif, was induced under acid stress. Furthermore, we examined antitoxin levels over time for MazEFBif and observed that the antitoxin MazEBif was degraded by ClpPXBif, which suggested that MazEFBif was activated through the hydrolysis of MazEBif by ClpP1XBif and ClpP2XBif under acid stress. Our results suggest that the MazEFBif TA module may play an important role in cell physiology and may represent a cell growth modulator that helps bacteria to cope with acid stress in the gastrointestinal tract and environment.


      PubDate: 2015-07-01T17:31:31Z
       
  • Characterisation of biofilms formed by Lactobacillus plantarum WCFS1 and
           food spoilage isolates
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Mónica D. Fernández Ramírez , Eddy J. Smid , Tjakko Abee , Masja N. Nierop Groot
      Lactobacillus plantarum has been associated with food spoilage in a wide range of products and the biofilm growth mode has been implicated as a possible source of contamination. In this study we analysed the biofilm forming capacity of L. plantarum WCFS1 and six food spoilage isolates. Biofilm formation as quantified by crystal violet staining and colony forming units was largely affected by the medium composition, growth temperature and maturation time and by strain specific features. All strains showed highest biofilm formation in Brain Heart Infusion medium supplemented with manganese and glucose. For L. plantarum biofilms the crystal violet (CV) assay, that is routinely used to quantify total biofilm formation, correlates poorly with the number of culturable cells in the biofilm. This can in part be explained by cell death and lysis resulting in CV stainable material, conceivably extracellular DNA (eDNA), contributing to the extracellular matrix. The strain to strain variation may in part be explained by differences in levels of eDNA, likely as result of differences in lysis behaviour. In line with this, biofilms of all strains tested, except for one spoilage isolate, were sensitive to DNase treatment. In addition, biofilms were highly sensitive to treatment with Proteinase K suggesting a role for proteins and/or proteinaceous material in surface colonisation. This study shows the impact of a range of environmental factors and enzyme treatments on biofilm formation capacity for selected L. plantarum isolates associated with food spoilage, and may provide clues for disinfection strategies in food industry.


      PubDate: 2015-07-01T17:31:31Z
       
  • Increase of fruity aroma during mixed T. delbrueckii/S. cerevisiae wine
           fermentation is linked to specific esters enhancement
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Philippe Renault , Joana Coulon , Gilles de Revel , Jean-Christophe Barbe , Marina Bely
      The aim of this work was to study ester formation and the aromatic impact of Torulaspora delbrueckii when used in association with Saccharomyces cerevisiae during the alcoholic fermentation of must. In order to evaluate the influence of the inoculation procedure, sequential and simultaneous mixed cultures were carried out and compared to pure cultures of T. delbrueckii and S. cerevisiae. Our results showed that mixed inoculations allowed the increase, in comparison to S. cerevisiae pure culture, of some esters specifically produced by T. delbrueckii and significantly correlated to the maximal T. delbrueckii population reached in mixed cultures. Thus, ethyl propanoate, ethyl isobutanoate and ethyl dihydrocinnamate were considered as activity markers of T. delbrueckii. On the other hand, isobutyl acetate and isoamyl acetate concentrations were systematically increased during mixed inoculations although not correlated with the development of either species but were rather due to positive interactions between these species. Favoring T. delbrueckii development when performing sequential inoculation enhanced the concentration of esters linked to T. delbrueckii activity. On the contrary, simultaneous inoculation restricted the growth of T. delbrueckii, limiting the production of its activity markers, but involved a very important production of numerous esters due to more important positive interactions between species. These results suggest that the ester concentrations enhancement via interactions during mixed modalities was due to S. cerevisiae production in response to the presence of T. delbrueckii. Finally, sensory analyses showed that mixed inoculations between T. delbrueckii and S. cerevisiae allowed to enhance the complexity and fruity notes of wine in comparison to S. cerevisiae pure culture. Furthermore, the higher levels of ethyl propanoate, ethyl isobutanoate, ethyl dihydrocinnamate and isobutyl acetate in mixed wines were found responsible for the increase of fruitiness and complexity.


      PubDate: 2015-07-01T17:31:31Z
       
  • Control of household mycoflora in fermented sausages using phenolic
           fractions from olive mill wastewaters
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Clemencia Chaves-López , Annalisa Serio , Giovanni Mazzarrino , Maria Martuscelli , Emidio Scarpone , Antonello Paparella
      Biopreservation using polyphenols represents an alternative to chemical molecules for improving food safety. In this work, we evaluated the antifungal activity of polyphenols extracted from olive mill wastewater (OMWWP) to reduce or eliminate the growth of undesired fungi on the surface of dry fermented sausages. Antagonism against Penicillium expansum DSMZ 1282, Penicillium verrucosum DSMZ 12639, Penicillium nalgiovense MS01, Aspergillus ochraceus DSMZ 63304, Cladosporium cladosporioides MS12, and Eurotium amstelodami MS10 was evident at 1.25% OMWWP in vitro, whereas in situ application of 2.5% OMWWP strongly reduced undesired household fungal species such as C. cladosporioides, Penicillium aurantiogriseum, Penicillium commune, and Eurotium amstelodami, while a moderate antagonistic activity towards P. nalgiovense and Penicillium chrysogenum was observed at the same concentration. OMWWP at the concentrations used in this study demonstrated species-dependent antifungal activity by inhibiting both fungal growth and spore germination. Therefore, OMWWP can be regarded as a potential alternative to synthetic antifungal compounds to preserve the product from both oxidation and undesired fungi, without changing the sensory characteristics.


      PubDate: 2015-07-01T17:31:31Z
       
  • Microbial analyses of traditional Italian salami reveal microorganisms
           transfer from the natural casing to the meat matrix
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Vincenza Pisacane , Maria Luisa Callegari , Edoardo Puglisi , Giuliano Dallolio , Annalisa Rebecchi
      In this study the bacterial biodiversity, during the maturation process of traditional sausages (Salame Mantovano), produced with two different kinds of casing (hog middle or “Crespone” and hog bung or “Gentile”), was investigated by means of culture-dependent and -independent methods. In order to assess the natural variability linked to the type of casing used in production, the ingredients, as well as ripening conditions, were identical in both productions. The aim of the study was to understand the contribution of casing microflora during sausage ripening by identifying the dominant species and strains. The bacterial ecology of casings and salami at different ripening stages, as determined by plating, revealed higher staphylococci and enterococci counts for Gentile casing and for the entire ripening period of the salami studied. After molecular identification of 219 Lactobacilli and 225 cocci gram positive catalase positive (GPCP) isolates, the species most frequently isolated were Lactobacillus sakei, Lactobacillus curvatus, Staphylococcus xylosus, and Staphylococcus saprophyticus. Some L. sakei and S. saprophyticus strains, coming from casing, were also found in the salami at different times of ripening. A richer biodiversity was only detected at the beginning of maturation. We also report the first detection, by PCR–DGGE method, of Arcobacter marinus and Brochothrix thermosphacta species in casings and Kokuria salsicia in fresh sausage. Results suggesting that casing can be an important source of bacteria during natural fermentation when starter cultures are not used.


      PubDate: 2015-07-01T17:31:31Z
       
  • Fungi in Ontario maple syrup &amp; some factors that determine the
           presence of mold damage
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Samantha L. Frasz , J. David Miller
      Maple syrup is a high value artisanal product produced mainly in Canada and a number of States primarily in the northeast USA. Mold growth (Wallemia sebi) on commercial product was first reported in syrup in 1908. Since then, few data have been published. We conducted a systematic examination for fungi in maple syrup from 68 producers from all of the syrup-producing areas of Ontario, Canada. The mean pH of the samples was pH6.82, sugar content averaged 68.0±0.89°Brix and aw averaged 0.841±0.011. Some 23 species of fungi were isolated based on morphology and molecular techniques. The most common fungus in the maple syrup samples was Eurotium herbariorum, followed by Penicillium chrysogenum, Aspergillus penicillioides, Aspergillus restrictus, Aspergillus versicolor and two species of Wallemia. Cladosporium cladosporioides was also common but only recovered when fungi known from high sugar substrates were also present in the mold damaged sample. The rarely reported yeast Citeromyces matrinsis was found in samples from three producers. There appear to be three potential causes for mold damage observed. High aw was associated with about one third of the mold damage. Independently, cold packing (bottling at ~25°C) was a risk factor. However, syrup of good quality and quite low aw values was contaminated. We hypothesize that sanitation in the bottling line and other aspects of the bottling process may be partial explanations. Clarifying this requires further study.


      PubDate: 2015-07-01T17:31:31Z
       
  • Effectiveness of levulinic acid and sodium dodecyl sulfate employed as a
           sanitizer during harvest or packing of cantaloupes contaminated with
           Salmonella Poona
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Cathy C. Webb , Marilyn C. Erickson , Lindsey E. Davey , Michael P. Doyle
      Freshly harvested Eastern variety cantaloupes (Cucumis melo L. var. reticulatus cv. Athena) were subjected to three different harvest and wash treatments to examine conditions under which the efficacy of the sanitizer, levulinic acid (LV) plus sodium dodecyl sulfate (SDS), could be enhanced to reduce Salmonella contamination. In treatment set one, cantaloupes were spot inoculated with Salmonella enterica serovar Poona (prepared from solid or liquid media cultures) before or after a 1-min dip treatment in LV (2.5, 5.0, 7.5, or 10%) and 2.5% SDS. S. Poona initial populations on rind tissue (4.26–5.04 log CFU/sample) were reduced to detection by enrichment culture when cantaloupes were subsequently exposed to any of the LV/SDS solutions. When S. Poona was introduced after cantaloupes had been dip-treated, greater decreases in pathogen populations at the stem scar were observed when cantaloupes were treated with increasing concentrations of LV. In treatment set two, the response of S. Poona dip-treated with 5% LV/2.5% SDS was compared to a simulated commercial dump tank treatment incorporating 200ppm chlorine as well as a two-stage treatment employing both the chlorine tank and LV/SDS dip treatments. S. Poona levels (log CFU/sample or # positive by enrichment culture/# analyzed) after treatments were 5.25, 3.07, 7/10, 5/10 (stem scar) and 3.90, 25/40, 28/40, 20/40 (rind) for non-treated, chlorine tank, LV/SDS dip, and tank plus dip treatments, respectively. In treatment set three, freshly harvested cantaloupes were first treated in the field using a needle-free stem scar injection (200μl, 7.5% LV/1.0% SDS, 60psi) and a cantaloupe spray (30ml, 7.5% LV/0.5% SDS). Cantaloupe stem scar and rind tissue were then spot-inoculated with S. Poona using either a liquid or soil-based medium followed by a simulated dump tank treatment incorporating either 200ppm chlorine or 5% LV/2% SDS. S. Poona inoculated on field-treated cantaloupe rind decreased by 4.7 and 5.31 (liquid) and 3.27 and 3.36 (soil) log CFU/sample after simulated chlorine and LV/SDS tank treatments, respectively. In the case of stem scar tissue, S. Poona populations exhibited a 1.0 log greater reduction when cantaloupes were treated with LV/SDS compared to chlorine in the dump tank (P <0.05). Based on this study, application of multiple hurdles is warranted, as additional decreases in S. Poona populations were obtained when cantaloupes were subjected to a chlorine dump tank followed by a LV/SDS dip treatment.


      PubDate: 2015-07-01T17:31:31Z
       
  • Incorporation of nisin Z and lauric arginate into pullulan films to
           inhibit foodborne pathogens associated with fresh and ready-to-eat muscle
           foods
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Rinrada Pattanayaiying , Aran H-Kittikun , Catherine N. Cutter
      A combination of food grade compounds with edible films, used to inhibit foodborne pathogens associated with fresh or further processed muscle foods, is receiving considerable attention. In this study, pullulan films containing lauric arginate (LAE) and nisin Z (produced by Lactococcus lactis subsp. lactis I8-7-3 and isolated from catfish gut), alone or in combination, were investigated for controlling foodborne pathogens on fresh and further processed muscle foods after long-term refrigerated storage. Salmonella Typhimurium and Salmonella Enteritidis on raw turkey breast slices wrapped with a film containing LAE or the combination of LAE with nisin Z were reduced throughout the experiment, 2.5 to 4.5log10 CFU/cm2 and 3.5 to 5.1log10 CFU/cm2, respectively. Film containing a combination of LAE with nisin Z reduced Staphylococcus aureus and Listeria monocytogenes Scott A inoculated onto ham surfaces by approximately 5.53 and 5.62log10 CFU/cm2, respectively during refrigerated storage. Escherichia coli O157:H7, O111, and O26 also were reduced by >4log10 CFU/cm2 on raw beef slices after treatment with the combination film and refrigerated storage. The results obtained from this study indicate the LAE- and LAE–nisin Z-containing pullulan films displayed excellent inhibition against foodborne pathogens on fresh and further processed muscle foods.


      PubDate: 2015-07-01T17:31:31Z
       
  • Prevalence and characterization of
           extended-spectrum-β-lactamase-producing Escherichia coli and
           Klebsiella pneumoniae in ready-to-eat vegetables
    • Abstract: Publication date: 17 August 2015
      Source:International Journal of Food Microbiology, Volume 207
      Author(s): Hong-Seok Kim , Jung-Whan Chon , Young-Ji Kim , Dong-Hyeon Kim , Mu-sang Kim , Kun-Ho Seo
      The objective of this investigation was to determine the prevalence and characteristics of extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae in ready-to-eat (RTE) vegetables. A total of 189 RTE vegetable samples (91 sprouts and 98 mixed salads) were collected in a retail market in South Korea from October 2012 to February 2013. The prevalence of ESBL-producing E. coli and K. pneumoniae was 10.1%. Of these, 94.7% were from the sprout samples. All isolates were resistant to cefotaxime, and many of the ESBL producers were also resistant to non-β-lactam antibiotics, including gentamicin, trimethoprim/sulfamethoxazole, and ciprofloxacin (73.7%, 63.2%, and 26.3% respectively). TEM-1, SHV-1, −2, −11, −12, −27, −28 and −61, and CTX-M-14, −15 and −55 β-lactamases were detected alone or in combination. The genetic platforms of all CTX-M producing isolates were ISEcp1-bla CTX-M-orf477 and ISEcp1-bla CTX-M-IS903 in CTX-M groups 1 and 9, respectively. To our knowledge, this is the first report of the prevalence and characterization of ESBL-producing E. coli and K. pneumoniae isolated from RTE vegetables. The results of this study indicate that RTE vegetables, sprouts, in particular, may play a role in spreading antimicrobial resistant bacteria and ESBL genes to humans.


      PubDate: 2015-07-01T17:31:31Z
       
  • Quality and Shelf-life Prediction for Retail Fresh Hake (Merluccius
           merluccius)
    • Abstract: Publication date: Available online 28 May 2015
      Source:International Journal of Food Microbiology
      Author(s): Míriam R. García , Carlos Vilas , Juan R. Herrera , Marta Bernárdez , Eva Balsa-Canto , Antonio A. Alonso
      Fish quality has a direct impact on market price and its accurate assessment and prediction is of main importance to set prices, increase competitiveness, resolve conflicts of interest and prevent food wastage due to conservative product shelf-life estimations. In this work we present a general methodology to derive predictive models of fish freshness under different storage conditions. The approach makes use of the theory of optimal experimental design, to maximize data information and in this way reduce the number of experiments. The resulting growth model for specific spoilage microorganisms in hake (Merluccius merluccius) is sufficiently informative to estimate quality sensory indexes under time-varying temperature profiles. In addition it incorporates quantitative information of the uncertainty induced by fish variability. The model has been employed to test the effect of factors such as fishing gear or evisceration, on fish spoilage and therefore fish quality. Results show no significant differences in terms of microbial growth between hake fished by long-line or bottom-set nets, within the implicit uncertainty of the model. Similar conclusions can be drawn for gutted and un-gutted hake along the experiment horizon. In addition, whenever there is the possibility to carry out the necessary experiments, this approach is sufficiently general to be used in other fish species and under different stress variables.


      PubDate: 2015-06-06T10:05:35Z
       
 
 
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