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MICROBIOLOGY (208 journals)                  1 2 3     

Acta Microbiologica et Immunologica Hungarica     Full-text available via subscription   (Followers: 6)
Addiction Genetics     Open Access   (Followers: 3)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 12)
Advances in Microbiology     Open Access   (Followers: 13)
Advances in Molecular Imaging     Open Access   (Followers: 3)
African Journal of Clinical and Experimental Microbiology     Open Access   (Followers: 1)
African Journal of Microbiology Research     Open Access   (Followers: 1)
American Journal of Infectious Diseases and Microbiology     Open Access   (Followers: 10)
American Journal of Microbiological Research     Open Access  
American Journal of Microbiology     Open Access   (Followers: 13)
American Journal of Molecular Biology     Open Access   (Followers: 3)
American Journal of Stem Cell Research     Open Access   (Followers: 1)
Annals of Clinical Microbiology and Antimicrobials     Open Access   (Followers: 4)
Annals of Microbiology     Hybrid Journal   (Followers: 6)
Annual Review of Microbiology     Full-text available via subscription   (Followers: 21)
Antimicrobial Agents and Chemotherapy     Full-text available via subscription   (Followers: 11)
Applied and Environmental Microbiology     Full-text available via subscription   (Followers: 23)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 7)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 22)
Archives of Microbiology     Hybrid Journal   (Followers: 3)
Beneficial Microbes     Full-text available via subscription   (Followers: 2)
Bio-Research     Full-text available via subscription  
BioArchitecture     Full-text available via subscription  
Biocell     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 3)
Biomedical Research     Open Access   (Followers: 3)
BioMolecular Concepts     Full-text available via subscription   (Followers: 2)
Biomolecules     Open Access   (Followers: 1)
BMC Microbiology     Open Access   (Followers: 5)
Brazilian Journal of Microbiology     Open Access   (Followers: 2)
Canadian Journal of Infectious Diseases & Medical Microbiology     Hybrid Journal   (Followers: 1)
Canadian Journal of Microbiology     Full-text available via subscription   (Followers: 4)
Cell Biology : Research & Therapy     Partially Free  
Cell Host & Microbe     Full-text available via subscription   (Followers: 5)
Cell Medicine     Open Access  
Cell Regeneration     Open Access  
Cell Stem Cell     Full-text available via subscription   (Followers: 16)
Cells     Open Access  
Cellular & Molecular Immunology     Hybrid Journal   (Followers: 8)
Cellular Microbiology     Hybrid Journal   (Followers: 4)
Cheese: Chemistry, Physics and Microbiology     Full-text available via subscription   (Followers: 2)
Chimerism     Full-text available via subscription  
Clinical Microbiology and Infection     Hybrid Journal   (Followers: 12)
Clinical Microbiology Newsletter     Hybrid Journal   (Followers: 2)
Clinical Microbiology Reviews     Full-text available via subscription   (Followers: 9)
Comparative Immunology, Microbiology and Infectious Diseases     Hybrid Journal   (Followers: 7)
Computational Molecular Bioscience     Open Access   (Followers: 1)
Continental Journal of Microbiology     Open Access   (Followers: 3)
Critical Reviews in Microbiology     Hybrid Journal   (Followers: 5)
Current Issues in Molecular Biology     Open Access  
Current Microbiology     Hybrid Journal   (Followers: 4)
Current Molecular Imaging     Hybrid Journal  
Current Opinion in Microbiology     Hybrid Journal   (Followers: 14)
Current Tissue Engineering     Hybrid Journal   (Followers: 1)
Current Topics in Microbiology and Immunology     Hybrid Journal   (Followers: 2)
Diagnostic Microbiology and Infectious Disease     Hybrid Journal   (Followers: 2)
Disease and Molecular Medicine     Open Access   (Followers: 1)
DNA Barcodes     Open Access  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
Emerging Microbes & Infections     Open Access   (Followers: 1)
Environmental Microbiology     Hybrid Journal   (Followers: 7)
Environmental Microbiology Reports     Hybrid Journal   (Followers: 3)
Enzyme and Microbial Technology     Hybrid Journal   (Followers: 6)
Epigenetics of Degenerative Diseases     Open Access  
European Journal of Clinical Microbiology & Infectious Diseases     Hybrid Journal   (Followers: 9)
European Journal of Microbiology and Immunology     Open Access   (Followers: 5)
Experimental and Molecular Pathology     Hybrid Journal  
Fems Immunology & Medical Microbiology     Hybrid Journal   (Followers: 6)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 6)
Fems Microbiology Letters     Hybrid Journal   (Followers: 13)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 15)
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Microbiology     Hybrid Journal   (Followers: 11)
Frontiers in Cell and Developmental Biology     Open Access   (Followers: 1)
Frontiers in Cellular and Infection Microbiology     Open Access   (Followers: 2)
Frontiers in Cellular Neuroscience     Open Access  
Frontiers in Microbiology     Open Access   (Followers: 4)
Frontiers in Molecular Neuroscience     Open Access  
Future Microbiology     Full-text available via subscription   (Followers: 1)
Future Virology     Full-text available via subscription   (Followers: 3)
Gene Expression     Full-text available via subscription  
Genetica si Biologie Moleculara     Open Access   (Followers: 1)
Genetics and Molecular Research     Open Access   (Followers: 2)
Geomicrobiology Journal     Hybrid Journal   (Followers: 1)
Gut Microbes     Full-text available via subscription   (Followers: 1)
Indian Journal of Microbiology     Hybrid Journal   (Followers: 1)
Indian Journal of Pathology and Microbiology     Open Access   (Followers: 1)
Infection Ecology & Epidemiology     Open Access   (Followers: 6)
International Arabic Journal of Antimicrobial Agents     Open Access   (Followers: 4)
International Journal of Antimicrobial Agents     Hybrid Journal  
International Journal of Bacteriology     Open Access  
International Journal of Bioassays     Open Access   (Followers: 5)
International Journal of Biotechnology and Molecular Biology Research     Open Access  
International Journal of Food Microbiology     Hybrid Journal   (Followers: 11)
International Journal of Infection and Microbiology     Open Access   (Followers: 1)
International Journal of Medical Microbiology     Hybrid Journal   (Followers: 4)
International Journal of Systematic and Evolutionary Microbiology     Full-text available via subscription   (Followers: 2)
International Microbiology     Open Access   (Followers: 2)
Invertebrate Immunity     Open Access  

        1 2 3     

Journal Cover International Journal of Food Microbiology
   [13 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0168-1605
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.386]   [H-I: 108]
  • The Influence of Serial Repitching of Saccharomyces pastorianus on its
           Karyotype and Protein Profile during the Fermentation of Gluten-free
           Buckwheat and Quinoa Wort
    • Abstract: Publication date: Available online 3 June 2014
      Source:International Journal of Food Microbiology
      Author(s): Matjaž Deželak , Mekonnen M. Gebremariam , Neža Čadež , Jure Zupan , Peter Raspor , Martin Zarnkow , Thomas Becker , Iztok Jože Košir
      Gluten-free beer-like beverages from malted buckwheat and quinoa are somehow close to their commercial production, but rather high expenses are expected due to the relatively high price of grain, some technological adaptations of process and the need for external enzyme supplementation during mashing. One of the common and efficient cost reduction measures in the industrial scale is serial repitching of the yeast biomass, which has not been studied for the buckwheat and quinoa wort fermentation before. In that manner we have monitored possible changes in yeast's proteins and chromosomal DNA during eleven serial repitchings of the yeast Saccharomyces pastorianus strain TUM 34/70 for fermentation of the barley, buckwheat and quinoa wort. Karyotypes showed changes in regard to the raw materials used and many responsible candidate proteins are suggested which could cause these differences. Different relative expression of some protein bands was also linked to the proteins involved in yeast stress response and proteins involved in fermentation performance. Results suggest that serial repitching of the strain TUM 34/70 seems suitable for the production of gluten-free beer-like beverages from buckwheat and quinoa.


      PubDate: 2014-06-07T14:26:52Z
       
  • Editorial Board
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183




      PubDate: 2014-06-01T14:22:34Z
       
  • Microbiota dynamics related to environmental conditions during the
           fermentative production of Fen-Daqu, a Chinese industrial fermentation
           starter
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): Xiao-Wei Zheng , Zheng Yan , M.J. Robert Nout , Eddy J. Smid , Marcel H. Zwietering , Teun Boekhout , Jian-Shu Han , Bei-Zhong Han
      Chinese Daqu is used as a starter for liquor and vinegar fermentations. It is produced by solid state fermentation of cereal–pulse mixtures. A succession of fungi, lactic acid bacteria and Bacillus spp. was observed during the production of Daqu. Mesophilic bacteria followed by fungi, dominated the first phase of fermentation. Next, lactic acid bacteria increased in relative abundance, resulting in an increase of the acidity of Daqu. At the final stages of fermentation, Bacillus spp. and thermophilic fungi became the dominant groups, possibly due to their tolerance to low water activity and high temperature. Both culture-dependent and culture-independent analyses confirmed that Bacillus spp. were ubiquitous throughout the process. Yeast species such as Wickerhamomyces anomalus, Saccharomycopsis fibuligera and Pichia kudriavzevii were present throughout almost the entire fermentation process, but the zygomycetous fungus Lichtheimia corymbifera proliferated only during the final stages of fermentation. Canonical correspondence analysis (CCA) revealed the significance of acidity, moisture content and temperature in correlation with the composition of the microbial communities at different stages.


      PubDate: 2014-06-01T14:22:34Z
       
  • Announcement
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183




      PubDate: 2014-06-01T14:22:34Z
       
  • Biocontrol activity of an alkaline serine protease from Aureobasidium
           pullulans expressed in Pichia pastoris against four postharvest pathogens
           on apple
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): Houda Banani , Davide Spadaro , Dianpeng Zhang , Slavica Matic , Angelo Garibaldi , Maria Lodovica Gullino
      The yeast-like fungus Aureobasidium pullulans PL5 is a microbial antagonist against postharvest pathogens of fruits. The strain is able to produce hydrolases, including glucanases, chitinases and proteases. The alkaline serine protease gene ALP5 from A. pullulans was cloned, inserted into the vector pPIC9 to construct pPIC9/ALP5, and then expressed in Pichia pastoris strain KM71. ALP5 had a molecular mass of 42.9kDa after 5days growth with 1% methanol induction at 28°C. The recombinant protease expressed in P. pastoris showed its highest activity under alkaline conditions (at pH10) and a temperature of 50°C. The antifungal activity of the recombinant protease was investigated against Penicillium expansum, Botrytis cinerea, Monilinia fructicola and Alternaria alternata in vitro and on apple. The recombinant protease reduced significantly the spore germination and the germ tube length of the tested pathogens in PDB medium. The highest level of protease efficacy was observed against M. fructicola and B. cinerea, whereas a lower efficacy was observed against P. expansum and A. alternata indicating a possible effect of the pathogen cell wall composition on the proteolytic activity of the recombinant protease. The presence of protease was able to cause the swelling of the hyphae of B. cinerea, under an optical microscope. The recombinant protease expressed in P. pastoris was more active against the pathogens in vitro than the same enzyme expressed in E. coli in previous studies. The efficacy of ALP5 was also evaluated against the pathogens in vivo on cv Golden Delicious apples. The protease was more efficient in controlling M. fructicola, B. cinerea and P. expansum than A. alternata. However, the extent of the activity was dependent on the enzyme concentration and the length of fruit storage. This study demonstrated the capacity of the alkaline serine protease to keep its enzymatic activity for some days in the unfavorable environment of the fruit wounds. The alkaline serine protease could be developed as a postharvest treatment with antimicrobial activity for fruit undergoing a short storage period.


      PubDate: 2014-05-25T15:37:54Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181




      PubDate: 2014-05-25T15:37:54Z
       
  • Editorial Board
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181




      PubDate: 2014-05-25T15:37:54Z
       
  • Evidence for a reversible drought induced shift in the species composition
           of mycotoxin producing Fusarium head blight pathogens isolated from
           symptomatic wheat heads
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): Marco Beyer , Friederike Pogoda , Marine Pallez , Joëlle Lazic , Lucien Hoffmann , Matias Pasquali
      Fusarium species are fungal plant pathogens producing toxic secondary metabolites such as deoxynivalenol (DON), 15-acetyl-deoxynivalenol (15AcDON) and nivalenol (NIV). In Luxembourg, the Fusarium species composition isolated from symptomatic winter wheat heads was dominated by Fusarium graminearum sensu stricto strains (genetic 15AcDON chemotype) between the years 2009 and 2012, except for 2011, when Fusarium culmorum strains (genetic NIV chemotype) dominated the pathogen complex. Previous reports indicated that F. graminearum sensu stricto (genetic 15AcDON chemotype) was also most frequently isolated from randomly sampled winter wheat kernels including symptomatic as well as asymptomatic kernels in 2007 and 2008. The annual precipitation (average of 10 weather stations scattered across the country) decreased continuously from 924.31mm in 2007 over 917.15mm in 2008, to 843.38mm in 2009, 736.24mm in 2010, and 575.09mm in 2011. In 2012, the annual precipitation increased again to 854.70mm. Hardly any precipitation was recorded around the time of wheat anthesis in the years 2010 and 2011, whereas precipitation levels >50mm within the week preceding anthesis plus the week post anthesis were observed in the other years. The shift to genetic NIV chemotype F. culmorum strains in 2011 was accompanied by a very minor elevation of average NIV contents (2.9ngg−1) in the grain. Our data suggest that high NIV levels in Luxembourgish winter wheat are at present rather unlikely, because the indigenous F. culmorum strains with the genetic NIV chemotype seem to be outcompeted under humid in vivo conditions by F. graminearum DON producing strains on the one hand and seem to be inhibited – even though to a lower extent than DON producing strains – under dry in vivo conditions on the other hand.


      PubDate: 2014-05-25T15:37:54Z
       
  • The influence of fat and monoacylglycerols on growth of spore-forming
           bacteria in processed cheese
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): Iva Hauerlandová , Eva Lorencová , František Buňka , Jan Navrátil , Kristýna Janečková , Leona Buňková
      Highly undesirable microbial contaminants of processed cheese are endospore-forming bacteria of the genera Bacillus and Clostridium. Survival of Bacillus subtilis, B. cereus, Clostridium butyricum and C. sporogenes was examined in model processed cheese samples supplemented with monoacylglycerols. In processed cheese samples, monoacylglycerols of undecanoic, undecenoic, lauric and adamantane-1-carboxylic acid at concentration of 0.15% w/w prevented the growth and multiplication of both Bacillus species throughout the storage period. The two species of Clostridium were less affected by monoacylglycerols in processed cheese samples and only partial inhibition was observed. The effect of milk fat content on microbial survival in processed cheese was also evaluated. The growth of Bacillus sp. was affected by the fat level of processed cheese while population levels of Clostridium sp. did not differ in processed cheese samples with 30, 40 and 50% fat in dry matter.


      PubDate: 2014-05-25T15:37:54Z
       
  • Assessment of high and low enterotoxin A producing Staphylococcus aureus
           strains on pork sausage
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): Nikoleta Zeaki , Rong Cao , Panagiotis N. Skandamis , Peter Rådström , Jenny Schelin
      Three Staphylococcus aureus strains representing different alleles of the Siphoviridae prophage-encoded enterotoxin A (SEA) gene, including two high-SEA-producing strains and one low-SEA-producing strain were studied to investigate sea expression and SEA formation on a frankfurter type of sausage. The effect of lactic acid, an antimicrobial compound used as a preservative in food, was also investigated on the same product. All three strains were grown on pork sausages at 15°C for 14days in the presence or absence of lactic acid (1 or 2% v/v). Growth, sea mRNA expression and SEA formation were regularly monitored and compared between non-treated and treated sausages. For all experiments performed, the extracellular SEA formation significantly differed between the high- and low-SEA-producing strains, although growth and viability were overall the same. For the low producer (Sa51), the accumulated amount of extracellular SEA formed after 14days was close to the detection limit (less than 1ng/g) in all conditions; while Sa21 and Sa17, the two high-producing strains, formed 250±25.37ng/g and 750±82.65ng/g in non-treated sausage and 150±75.75ng/g and 300±83.89ng/g when treated with 1% lactic acid, respectively, after 14days. Sausages treated with 2% lactic acid followed the same pattern as above, but with an extended lag phase to 4days and reduced levels of enterotoxin formed for all strains. The difference in the level of SEA between the two high-producing strains is most likely due to the different clonal lineages of the sea-encoded Siphoviridae phages where induction of the prophage potentially could be the reason for higher production of SEA in one of the lines. Furthermore, a prolonged expression of sea gene in the two high-producing strains was observed during the entire incubation period, while the sea expression was under the detection limit in the low-producing strain. This study indicates that the high-SEA-producing strains, especially the strains with the putative capacity of prophage induction, could be more relevant in food safety aspects than low-producing type of strains on pork sausage.


      PubDate: 2014-05-25T15:37:54Z
       
  • Effect of egg washing and correlation between cuticle and egg penetration
           by various Salmonella strains
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): Vaibhav C. Gole , Juliet R. Roberts , Margaret Sexton , Damian May , Andreas Kiermeier , Kapil K. Chousalkar
      In Australia, Europe and the United States, eggs and egg products are frequently associated with Salmonella food poisoning outbreaks. Many of the egg-associated Salmonella outbreaks have been due to the products such as mayonnaise, ice-cream and cold desserts which are eaten without cooking following the addition of raw egg. The ability of four Salmonella isolates (one each of S. Singapore, S. Adelaide, S. Worthington and S. Livingstone) to penetrate washed and unwashed eggs using whole egg and agar egg penetration methods was investigated in the current study. The results of the agar penetration experiment indicated that all the isolates used in the present study have the capacity to penetrate the eggshell. Eggshell penetration by the S. Worthington isolate was higher but not significant (p=0.06) in washed eggs compared to unwashed eggs. However, for all other isolates (S. Singapore, S. Adelaide and S. Livingstone), there was no significant difference in penetration of washed and unwashed eggs. Statistical analysis indicated that cuticle score was a significant linear predictor of Salmonella eggshell penetration. Whole egg penetration results showed that all of the Salmonella isolates used in the present study were capable of surviving on the eggshell surface after 21days of incubation (at 20°C) following a high dose of inoculation (105 CFU/mL). The combined data of all isolates demonstrated that, the survival rate of Salmonella on eggshells (inoculated with 105 CFU/mL) was significantly higher (p=0.002) at 20°C as compared to 37°C. S. Singapore, S. Worthington, and S. Livingstone were not detected in egg internal contents whereas S. Adelaide was detected in one egg's internal contents.


      PubDate: 2014-05-25T15:37:54Z
       
  • Numerical spatio-temporal characterization of Listeria monocytogenes
           biofilms
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): M. Mosquera-Fernández , P. Rodríguez-López , M.L. Cabo , E. Balsa-Canto
      As the structure of biofilms plays a key role in their resistance and persistence, this work presents for the first time the numerical characterization of the temporal evolution of biofilm structures formed by three Listeria monocytogenes strains on two types of stainless-steel supports, AISI 304 SS No. 2B and AISI 316 SS No. 2R. Counting methods, motility tests, fluorescence microscopy and image analysis were combined to study the dynamic evolution of biofilm formation and structure. Image analysis was performed with several well-known parameters as well as a newly defined parameter to quantify spatio-temporal distribution. The results confirm the interstrain variability of L. monocytogenes species regarding biofilm structure and structure evolution. Two types of biofilm were observed: homogeneous or flat and heterogeneous or clustered. Differences in clusters and in attachment and detachment processes were due mainly to the topography and composition of the two surfaces although an effect due to motility was also found.


      PubDate: 2014-05-25T15:37:54Z
       
  • Two-dimensional environmental profiles of growth and fumonisin production
           by Fusarium proliferatum on a wheat-based substrate
    • Abstract: Publication date: 16 July 2014
      Source:International Journal of Food Microbiology, Volumes 182–183
      Author(s): Eugenia Cendoya , María Cecilia Farnochi , Sofia Noemi Chulze , María Laura Ramirez
      The effect of water activity (aW; 0.995, 0.99, 0.98, 0.96, 0.94, 0.92, and 0.90), temperature (15, 25, and 30°C), incubation time (7, 14, 21 and 28days), and their interactions on mycelial growth and fumonisin production on wheat-based medium by three Fusarium proliferatum strains isolated from wheat in Argentina was evaluated. Maximum growth rates were obtained at the highest aW (0.995) and 30°C, with growth decreasing as the aW of the medium was reduced. Maximum amounts of total fumonisins (FB1, FB2 and FB3) were produced at 0.99 aW and 25°C after 21 and 28days of incubation for 2 strains, and at 15°C and 0.98 aW after 28days of incubation for the third strain. The fumonisin concentrations varied considerably depending on the aW and temperature interactions assayed. The studied strains had different fumonisin production profiles. F. proliferatum ITEM 15661 and ITEM 15664 produced FB1 and FB2 whereas F. proliferatum ITEM 15654 was able to produce FB1, FB2 and FB3. Interestingly, fumonisin production profiles for each particular strain were related to incubation temperatures. Fumonisins were produced from 15 to 30°C and at aW values of 0.92 to 0.995 after 21 to 28days of incubation. However at 7 and 14days of incubation small amounts of fumonisin were produced at aW lower than 0.94. Two-dimensional profiles of aW by temperature interactions were developed from these data to identify areas where conditions indicate a significant risk from fumonisin accumulation on wheat. Temperature and aW conditions that resulted in fumonisin production are those found during wheat grain development (especially milk and dough stages) in the field. This study provides useful base line data on conditions representing a high and a low risk for contamination of wheat by fumonisins which is becoming of greater concern because this cereal is destined mainly for human consumption.


      PubDate: 2014-05-25T15:37:54Z
       
  • Selection of non-Saccharomyces yeast strains for reducing alcohol levels
           in wine by sugar respiration
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Manuel Quirós , Virginia Rojas , Ramon Gonzalez , Pilar Morales
      Respiration of sugars by non-Saccharomyces yeasts has been recently proposed for lowering alcohol levels in wine. Development of industrial fermentation processes based on such an approach requires, amongst other steps, the identification of yeast strains which are able to grow and respire under the relatively harsh conditions found in grape must. This work describes the characterization of a collection of non-Saccharomyces yeast strains in order to identify candidate yeast strains for this specific application. It involved the estimation of respiratory quotient (RQ) values under aerated conditions, at low pH and high sugar concentrations, calculation of yields of ethanol and other relevant metabolites, and characterization of growth responses to the main stress factors found during the first stages of alcoholic fermentation. Physiological features of some strains of Metschnikowia pulcherrima or two species of Kluyveromyces, suggest they are suitable for lowering ethanol yields by respiration. The unsuitability of Saccharomyces cerevisiae strains for this purpose was not due to ethanol yields (under aerated conditions they are low enough for a significant reduction in final ethanol content), but to the high acetic acid yields under these growth conditions. According to results from controlled aeration fermentations with one strain of M. pulcherrima, design of an aeration regime allowing for lowering ethanol yields though preserving grape must components from excessive oxidation, would be conceivable.


      PubDate: 2014-05-15T10:14:55Z
       
  • Tracking Campylobacter contamination along a broiler chicken production
           chain from the farm level to retail in China
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Licai Ma , Yang Wang , Jianzhong Shen , Qijing Zhang , Congming Wu
      This study was conducted to determine the prevalence and distribution of Campylobacter species along a broiler production chain from farm to retail, and to evaluate the antimicrobial resistance profile of Campylobacter isolates. A total of 259 Campylobacter isolates (C. jejuni n=106, C. coli n=153) were isolated from broiler ceca samples (72.5%, 103/142), broiler carcasses (34.1%, 46/135), and retail broiler meat (31.3%, 40/128) samples collected in Shanghai, China. Minimal inhibitory concentrations of six antimicrobials were determined using the agar dilution method. High prevalence of resistance to ciprofloxacin (C. jejuni: 99.1%;C. coli: 100%) and tetracycline (C. jejuni: 100%;C. coli: 98.7%) was detected among the C. jejuni and C. coli isolates. The vast majority of C. coli were resistant to clindamycin (92.2%), gentamicin (95.4%), and erythromycin (94.1%), but only 25.5%, 53.8%, and 16.0% of C. jejuni exhibited resistance to these three antimicrobials, respectively. In contrast, the prevalence of florfenicol resistance in C. jejuni (37.7%) was significantly higher than that in C. coli (7.8%) (P <0.05). It is noteworthy that all Campylobacter isolates were resistant to one or more antimicrobials, and 71.7% of C. jejuni and 98.0% of C. coli isolates exhibited multi-drug resistance (resistant to three or more antimicrobials). Fifty-five C. jejuni and sixty C. coli isolates, selected from different production stages, species, and antimicrobial resistance patterns, were analyzed by pulsed field gel electrophoresis (PFGE), among which 15 unique PFGE patterns (PFGE patterns represented by a single strain) and 31 clusters (PFGE patterns represented by multiple strains) were detected. Furthermore, nearly all of the PFGE patterns of the Campylobacter strains isolated from retail broiler meats overlapped with those of the strains from ceca and slaughterhouse carcasses. Together, these findings revealed the high prevalence of Campylobacter species in a broiler chicken production chain, and the concerning situation of antimicrobial resistance in Campylobacter species. The findings also indicated that Campylobacter isolates from retail broiler meats were associated with fecal contamination in the slaughterhouse, underlying the need for improved measures for reducing carcass contamination in slaughter plants.


      PubDate: 2014-05-15T10:14:55Z
       
  • Microbiological quality and safety assessment of lettuce production in
           Brazil
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Siele Ceuppens , Claudia Titze Hessel , Rochele de Quadros Rodrigues , Sabrina Bartz , Eduardo César Tondo , Mieke Uyttendaele
      The microbiological quality and safety of lettuce during primary production in Brazil were determined by enumeration of hygiene indicators Escherichia coli, coliforms and enterococci and detection of enteric pathogens Salmonella and E. coli O157:H7 in organic fertilizers, soil, irrigation water, lettuce crops, harvest boxes and worker's hands taken from six different lettuce farms throughout the crop growth cycle. Generic E. coli was a suitable indicator for the presence of Salmonella and E. coli O157:H7, while coliforms and enterococci were not. Few pathogens were detected: 5 salmonellae and 2 E. coli O157:H7 from 260 samples, of which only one was lettuce and the others were manure, soil and water. Most (5/7) pathogens were isolated from the same farm and all were from organic production. Statistical analysis revealed the following environmental and agro-technical risk factors for increased microbial load and pathogen prevalence in lettuce production: high temperature, flooding of lettuce fields, application of contaminated organic fertilizer, irrigation with water of inferior quality and large distances between the field and toilets. Control of the composting process of organic fertilizers and the irrigation water quality appear most crucial to improve and/or maintain the microbiological quality and safety during the primary production of lettuce.


      PubDate: 2014-05-15T10:14:55Z
       
  • Biocide and antibiotic susceptibility of Salmonella isolates obtained
           before and after cleaning at six Danish pig slaughterhouses
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Mette Rørbæk Gantzhorn , Karl Pedersen , John Elmerdahl Olsen , Line Elnif Thomsen
      Salmonella sp. continues to be one of the most important foodborne pathogens. Control measures in terms of cleaning and disinfection on food production plants are very important for limiting the risk of contaminated food products to reach the consumer. In the last decade concern has arisen that bacteria exposed to disinfectants can develop resistance toward disinfectants and can have a higher risk of developing antibiotic resistance. The objectives of this study were to examine the prevalence of biocide resistant Salmonella sp. in Danish pig slaughterhouses, to evaluate if there was a correlation between susceptibilities to biocides and antibiotics, and to examine if cleaning and disinfection select isolates with changed susceptibility toward biocides or antibiotics. Salmonella sp. was isolated from the environment in Danish pig slaughterhouses before and after cleaning and disinfection. The susceptibility toward three different biocides, triclosan and two commercial disinfection products: Desinfect Maxi, a quaternary ammonium compound, and Incimaxx DES, an acetic compound, was determined. We found no resistance toward the biocides tested, but we did find that isolates obtained after cleaning had higher minimum inhibitory concentration (MIC) values toward one of the disinfectants (Incimaxx DES) compared to isolates obtained before cleaning and disinfection. This could indicate selection of strains that are more tolerant, due to the cleaning and disinfection. Furthermore, we found that there was a weak statistical correlation between MICs toward the biocides and some antibiotics, but no difference in log(MIC)s toward antibiotics between isolates obtained before and after cleaning, nor did we find any difference in the number of resistances of isolates obtained before and after cleaning and disinfection.


      PubDate: 2014-05-15T10:14:55Z
       
  • Diversity and functional characterization of Lactobacillus spp. isolated
           throughout the ripening of a hard cheese
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): J. Bautista-Gallego , V. Alessandria , M. Fontana , S. Bisotti , S. Taricco , P. Dolci , L. Cocolin , K. Rantsiou
      The aim of this work was to study the Lactobacillus spp. intra- and inter- species diversity in a Piedmont hard cheese made of raw milk without thermal treatment and without addition of industrial starter, and to perform a first screening for potential functional properties. A total of 586 isolates were collected during the cheese production and identified by means of molecular methods: three hundred and four were identified as Lactobacillus rhamnosus, two hundred and forty as Lactobacillus helveticus, twenty six as Lactobacillus fermentum, eleven as Lactobacillus delbrueckii, three as Lactobacillus pontis, and two as Lactobacillus gasseri and Lactobacillus reuteri, respectively. A high genetic heterogeneity was detected by using the repetitive bacterial DNA element fingerprinting (rep-PCR) with the use of (GTG)5 primer resulting in eight clusters of L. helveticus and sixteen clusters in the case of L. rhamnosus. Most of isolates showed a high auto-aggregation property, low hydrophobicity values, and a general low survival to simulated digestion process. However, sixteen isolates showed promising functional characteristics.


      PubDate: 2014-05-15T10:14:55Z
       
  • Editorial Board
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180




      PubDate: 2014-05-15T10:14:55Z
       
  • ICFMH Announcment
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180




      PubDate: 2014-05-15T10:14:55Z
       
  • Optimization of the reactional medium and a food impact study for a
           colorimetric in situ Salmonella spp. detection method
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Thomas Junillon , David Mosticon , Benoît Mallen , Florent Baril , Lucie Morand , Déborah Michel , Jean-Pierre Flandrois
      Foodborne pathogens are still a major concern for public health authorities. In this paper, we describe the optimization of a previously reported method which combines a highly specific capture of targeted food pathogens with an intracellular staining method. The reaction medium was optimized to simultaneously allow specific enrichment of Salmonella and maximize the staining of the target pathogen. This in situ colorimetric concept was evaluated with a broad range of food samples artificially contaminated with low levels of stressed Salmonella to mimic natural contamination conditions. This direct detection method compared favorably to a commercially available immunoassay system (Vidas® UP Salmonella), for cooked meat, dry milk powder and egg products. Globally 88% agreement was obtained between the two methods with a sensitivity of 80% and a specificity of 100% for the tested method. Main discordances were obtained with food matrices having high levels of competitive Gram negative microflora. These observations show that the design of an adapted culture medium is necessary to enhance the specific in situ capture and revelation system.


      PubDate: 2014-05-15T10:14:55Z
       
  • A quantitative risk assessment model for Vibrio parahaemolyticus in raw
           oysters in Sao Paulo State, Brazil
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Paulo de S. Costa Sobrinho , Maria T. Destro , Bernadette D.G.M. Franco , Mariza Landgraf
      A risk assessment of Vibrio parahaemolyticus associated with raw oysters produced and consumed in São Paulo State was developed. The model was built according to the United States Food and Drug Administration framework for risk assessment. The outcome of the exposure assessment estimated the prevalence and density of pathogenic V. parahaemolyticus in raw oysters from harvest to consumption. The result of the exposure step was combined with a Beta–Poisson dose–response model to estimate the probability of illness. The model predicted that the average risks per serving of raw oysters were 4.7×10−4, 6.0×10−4, 4.7×10−4 and 3.1×10−4 for spring, summer, fall and winter, respectively. Sensitivity analyses indicated that the most influential variables on the risk of illness were the total density of V. parahaemolyticus at harvest, transport temperature, relative prevalence of pathogenic strains and storage time at retail. Only storage time under refrigeration at retail showed negative correlation with the risk of illness.


      PubDate: 2014-05-10T11:15:21Z
       
  • Supplementation of Bolton broth with triclosan improves detection of
           Campylobacter jejuni and Campylobacter coli in chicken carcass rinse
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Jung-Whan Chon , Young-Ji Kim , Hong-Seok Kim , Dong-Hyeon Kim , Hyunsook Kim , Kwang-Young Song , Kun-Ho Seo
      We compared Bolton enrichment broth supplemented with antimicrobial triclosan (T-Bolton broth) and normal Bolton broth for the isolation of Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) from chicken carcass rinse. Whole chickens were rinsed with buffered peptone water prior to enrichment in normal Bolton broth or T-Bolton broth, followed by inoculation onto modified charcoal-cefoperazone-deoxycholate agar (mCCDA). Suspect colonies were confirmed by PCR. We observed a significantly higher number of C. jejuni or C. coli-positive samples in the T-Bolton broth (71.3%) than in the normal Bolton broth (27.5%) (p <0.05). Furthermore, the number of contaminated mCCDA plates was lower after enrichment in T-Bolton broth (3.8%) than in the normal Bolton broth (75%) (p <0.05), indicating that T-Bolton broth has higher selectivity. Finally, we identified extended-spectrum β-lactamase-producing Escherichia coli as the predominant competing flora in normal Bolton broth. In conclusion, the use of T-Bolton broth results in significant elimination of competing bacteria.


      PubDate: 2014-05-10T11:15:21Z
       
  • Cultivation-independent analysis of microbial communities on Austrian raw
           milk hard cheese rinds
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Elisa Schornsteiner , Evelyne Mann , Othmar Bereuter , Martin Wagner , Stephan Schmitz-Esser
      “Vorarlberger Bergkäse” (VB) is an Austrian artisanal hard cheese produced from raw cow's milk. The composition of its rind microbiota and the changes in the microbial communities during ripening have not previously been investigated. This study used 16S and 18S rRNA gene cloning and sequencing to characterize the bacterial and fungal communities of seven pooled cheese rind samples taken in seven different ripening cellars of three Austrian dairy facilities. A total of 408 clones for 16S and 322 clones for 18S rRNA gene libraries were used for taxonomic classification, revealing 39 bacterial and seven fungal operational taxonomic units (OTUs). Bacterial OTUs belonged to four different phyla. Most OTUs were affiliated to genera often found in cheese, including high numbers of coryneforms. The most abundant OTU from 16S rRNA gene libraries showed highest similarity to Halomonas. Young cheese rinds were dominated by Actinobacteria or Proteobacteria, particularly by Halomonas and Brevibacterium aurantiacum, while Staphyloccocus equorum was most abundant in old cheeses. The most abundant 18S rRNA OTU had highest similarity to the filamentous fungus Scopulariopsis brevicaulis. Pairwise correlation analyses revealed putative co-occurrences between a number of OTUs. It was possible to discriminate the different cheese rind microbiota at the community-level by facility affiliation and ripening time. This work provides insights into the microbial composition of VB cheese rinds and might allow the processing- and ripening conditions to be improved to enhance the quality of the product.


      PubDate: 2014-05-10T11:15:21Z
       
  • Use of sourdough fermentation and mixture of wheat, chickpea, lentil and
           bean flours for enhancing the nutritional, texture and sensory
           characteristics of white bread
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Carlo Giuseppe Rizzello , Maria Calasso , Daniela Campanella , Maria De Angelis , Marco Gobbetti
      This study aimed at investigating the addition of legume (chickpea, lentil and bean) flours to wheat flour bread. Type I sourdough containing legumes or wheat–legume flours were prepared and propagated (back slopped) in laboratory, according to traditional protocols that are routinely used for making typical Italian breads. Based on kinetic of acidification and culture-dependent data, the wheat–legume sourdough was further characterized and selected for bread making. As determined by RAPD-PCR and partial sequencing of 16S rDNA gene analyses, lactic acid bacteria in wheat–legume sourdough included Lactobacillus plantarum, Lactobacillus sanfranciscensis, Leuconostoc mesenteroides, Lactobacillus fermentum, Weissella cibaria, Lactobacillus pentosus, Lactobacillus coryneformis, Lactobacillus rossiae, Lactobacillus brevis, Lactobacillus parabuchneri and Lactobacillus paraplantarum. Two breads containing 15% (w/w) of legume (chickpea, lentil and bean) flours were produced using selected wheat–legume sourdough (WLSB) and traditional wheat sourdough (WSB). Compared to wheat yeasted bread (WYB), the level of total free amino acids (FAA) was higher in WSB and WLSB. Phytase and antioxidant activities were the highest in WLSB. Compared to bread WYB, the addition of legume flours decreased the in vitro protein digestibility (IVPD) (WYB versus WSB). However, the dough fermentation with WSLB favored an increase of IVPD. According to the levels of carbohydrates, dietary fibers and resistant starch, WSB and WLSB showed lower values of hydrolysis index (HI) compared to WYB. As showed by texture and image analyses and sensory evaluation of breads, a good acceptability was found for WSB and, especially, WLSB breads.


      PubDate: 2014-05-10T11:15:21Z
       
  • Population heterogeneity and dynamics in starter culture and lag phase
           adaptation of the spoilage yeast Zygosaccharomyces bailii to weak acid
           preservatives
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Malcolm Stratford , Hazel Steels , Gerhard Nebe-von-Caron , Simon V. Avery , Michaela Novodvorska , David B. Archer
      The food spoilage yeast Zygosaccharomyces bailii shows great resistance to weak-acid preservatives, including sorbic acid (2, 4-hexadienoic acid). That extreme resistance was shown to be due to population heterogeneity, with a small sub-population of cells resistant to a variety of weak acids, probably caused by a lower internal pH reducing the uptake of all weak acids. In the present paper, it was found that resistant cells were extremely rare in exponential cultures, but increased by up to 8000-fold in stationary phase. Inoculation of media containing sorbic acid with a population of Z. bailii cells gave rise to what appeared to be a prolonged lag phase, suggesting adaptation to the conditions before the cells entered the period of exponential growth. However, the apparent lag phase caused by sorbic acid was largely due to the time required for the resistant sub-population to grow to detectable levels. The slow growth rate of the sub-population was identical to that of the final total population. The non-resistant bulk population remained viable for 3days but had lost viability by 6days and, during that time, there was no indication of any development of resistance in the bulk population. The sub-population growing in sorbic acid showed very high population diversity in colony size and internal pH. After removal of sorbic acid, the population rapidly reverted back to the normal, largely non-resistant, population distribution. The data presented suggest that a reevaluation of the lag phase in microbial batch culture is required, at least for the resistance of Z. bailii to sorbic acid. Furthermore, the significance of phenotypic diversity and heterogeneity in microbial populations is discussed more broadly with potential relevance to bacterial “persisters”, natural selection and evolution.


      PubDate: 2014-05-10T11:15:21Z
       
  • The compositional mosaic of Fusarium species and their mycotoxins in
           unprocessed cereals, food and feed products in Belgium
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Adriaan Vanheule , Kris Audenaert , Marthe De Boevre , Sofie Landschoot , Boris Bekaert , Françoise Munaut , Mia Eeckhout , Monica Höfte , Sarah De Saeger , Geert Haesaert
      Global food safety depends on continuous monitoring of food contaminants such as mycotoxins in cereals and cereal-derived products. Here, we combine this type of investigation with quantitative occurrence data on Fusarium infestation of these products in extensive correlation studies. Finally, this contributes to a thorough understanding of the presence, origin and physiology of Fusarium Head Blight (FHB) related mycotoxins and the correlations within their ranks. Two hundred and thirty-seven samples were analyzed from diverse cereal matrices, representing the most important stages of the cereal food and feed chain in Belgium. Food, feed and non-processed field samples were investigated, with a strong emphasis on whole-grain food products. Two approaches were pursued to estimate the full scope of FHB and its repercussions: UPLC–MS/MS was applied to detect twelve different mycotoxins, and Q-PCR was used to measure the presence of ten Fusarium species. We found that different matrices have different characteristic contamination profiles, and extensive correlation studies identified certain mycotoxins for future assessment (e.g. moniliformin produced by the Fusarium avenaceum/Fusarium tricinctum species group). The investigated harvest year of 2012 yielded many non-processed field materials containing elevated levels of deoxynivalenol (DON), while even in a so-called DON-year less prevalent toxins such as T-2 and HT-2 might be considered problematic due to their consistent co-occurrence with related mycotoxins. Our data illustrate complex interactions between the many Fusarium species that are responsible for FHB and their mycotoxins. Correlation studies demonstrate that consistent co-occurrence of mycotoxins is not to be neglected, and pinpoint issues for future surveillance and legislation.


      PubDate: 2014-05-05T11:09:38Z
       
  • Butyric acid released during milk lipolysis triggers biofilm formation of
           Bacillus species
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): Ronit Pasvolsky , Varda Zakin , Ievgeniia Ostrova , Moshe Shemesh
      Bacillus species form biofilms within milking pipelines and on surfaces of equipment in the dairy industry which represent a continuous hygiene problem and can lead to serious economic losses due to food spoilage and equipment impairment. Although much is known about the mechanism by which the model organism Bacillus subtilis forms biofilms in laboratory mediums in vitro, little is known of how these biofilms are formed in natural environments such as milk. Besides, little is known of the signaling pathways leading to biofilm formation in other Bacillus species, such as Bacillus cereus and Bacillus licheniformis, both of which are known to contaminate milk. In this study, we report that milk triggers the formation of biofilm-related structures, termed bundles. We show this to be a conserved phenomenon among all Bacillus members tested. Moreover, we demonstrate that the tasA gene, which encodes a major portion of the matrix which holds the biofilm together, is vital for this process. Furthermore, we show that the free fatty acid (FFA) — butyric acid (BA), which is released during lipolysis of milk fat and demonstrates antimicrobial activity, is the potent trigger for biofilm bundle formation. We finally show that BA-triggered biofilm bundle formation is mediated by the histidine kinase, KinD. Taken together, these observations indicate that BA, which is a major FFA within milk triggers biofilm formation in a conserved mechanism among members of the Bacillus genus.


      PubDate: 2014-05-05T11:09:38Z
       
  • The combined effect of pasteurization intensity, water activity, pH and
           incubation temperature on the survival and outgrowth of spores of Bacillus
           cereus and Bacillus pumilus in artificial media and food products
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): S. Samapundo , M. Heyndrickx , R. Xhaferi , I. de Baenst , F. Devlieghere
      The objective of the study was to evaluate the combined effects of pasteurization intensity (no heat treatment and 10min at 70, 80 and 90°C), water activity (a w) (0.960–0.990), pH (5.5–7.0) and storage temperature (7 and 10°C) on the survival and outgrowth of psychrotolerant spores of Bacillus cereus FF119b and Bacillus pumilus FF128a. The experiments were performed in both artificial media and a validation was performed on real food products (cream, béchamel sauce and mixed vegetable soup). It was determined that in general, heat treatments of 10min at 70°C or 80°C activated the spores of both B. cereus FF119b and B. pumilus FF128a, resulting in faster outgrowth compared to native (non-heat treated) spores. A pasteurization treatment of 10min at 90°C generally resulted in the longest lag periods before outgrowth of both isolates. Some of the spores were inactivated by this heat treatment, with more inactivation being observed the lower the pH value of the heating medium. Despite this, it was also observed that under some conditions the remaining (surviving) spores were actually activated as their outgrowth took place after a shorter period of time compared to native non-heated spores. While the response of B. cereus FF119b to the pasteurization intensity in cream and béchamel sauce was similar to the trends observed in the artificial media at 10°C, in difference, outgrowth was only observed at 7°C in both products when the spores had been heated for 10min at 80°C. Moreover, no inactivation was observed in cream or béchamel sauce when the spores were heated for 10min at 90°C in these two products. This was attributed to the protective effect of fat in the cream and the ingredients in the béchamel sauce. The study provides some insight into the potential microbial (stability and safety) consequences of the current trend towards milder heat treatments which is being pursued in the food industry.


      PubDate: 2014-05-05T11:09:38Z
       
  • The loss of the inducible Aspergillus carbonarius MFS transporter MfsA
           leads to ochratoxin A overproduction
    • Abstract: Publication date: 2 July 2014
      Source:International Journal of Food Microbiology, Volume 181
      Author(s): A. Crespo-Sempere , P.V. Martínez-Culebras , L. González-Candelas
      Ochratoxin A (OTA), a nephrotoxic compound produced by certain Aspergillus and Penicillium species, is one of the most abundant mycotoxins in food commodities. Aspergillus carbonarius is the main source of OTA in wine, grape juice and dried vine fruits. Although many studies have focused on OTA production by A. carbonarius, little is known about the genes related to OTA production and transport. We have found a transporter that belongs to the major facilitator superfamily (MfsA) which is highly expressed with a 102-fold induction in an ochratoxigenic A. carbonarius strain compared to a low OTA producer strain. The encoding mfsA gene shows similarity to the multidrug efflux transporter flu1 from Candida albicans. A high number of putative transcription factor binding sites involved in the response to stress were identified within the promoter of mfsA. Phenotypical analysis of ΔmfsA deletion mutants revealed that the loss of mfsA leads to a slight growth reduction and increased OTA production. We therefore hypothesize that MfsA could be a stress response transporter whose disruption could cause an increase in oxidative stress together with a stimulation of mycotoxin production.


      PubDate: 2014-05-05T11:09:38Z
       
  • Resveratrol against Arcobacter butzleri and Arcobacter cryaerophilus:
           Activity and effect on cellular functions
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Susana Ferreira , Filomena Silva , João A. Queiroz , Mónica Oleastro , Fernanda C. Domingues
      The frequent isolation of Arcobacter butzleri and Arcobacter cryaerophilus from food samples makes it imperative to search for potential compounds able to inhibit the development of these bacteria. Taking this into consideration, this study focuses on the antimicrobial activity of resveratrol and its mechanism of action against A. butzleri and A. cryaerophilus. The activity of resveratrol was assessed by a microdilution method and time–kill curves. Resveratrol effect on cellular functions was assessed by flow cytometry evaluating intracellular DNA content and metabolic activity. Ethidium bromide (EtBr) accumulation in the presence of resveratrol was also evaluated, as well as the susceptibility to resveratrol in the presence of phenylalanine-arginine β-naphthylamide (PAβN). Scanning electron microscopy (SEM) was used to further evaluate cell damage caused by resveratrol. Resveratrol presented MIC values of 100 and 50μg/mL to A. butzleri and A. cryaerophilus, respectively. Based on the time–kill curves, resveratrol exhibited bactericidal activity, leading to a ≥3log10 CFU/mL reduction of initial inoculums, for A. butzleri exponential phase cells incubated for 6h with 1× MIC or with 2× MIC after 24h for stationary phase cells. For A. cryaerophilus cells in exponential growth phase, 99.9% killing was achieved after 24h incubation with 2× MIC, whereas, for stationary phase cells, bactericidal activity was only detected after incubation with 4× MIC. Incubation with resveratrol led to a decrease in both intracellular DNA content and metabolic activity. An increase in the accumulation of EtBr was observed in the presence of resveratrol, and the efflux pump inhibitor PAβN reduced the MIC of resveratrol. SEM analysis revealed disintegration of A. butzleri cells treated with resveratrol, whereas no morphological alteration was observed for A. cryaerophilus cells. Resveratrol has a good anti-Arcobacter activity, and the results obtained suggest that this compound could act through several different mechanisms in the inhibition of this microorganism. The results encourage the use of this compound for the development of potential strategies to control Arcobacter in food products.


      PubDate: 2014-04-30T10:38:23Z
       
  • Identification of the significant factors in food safety using global
           sensitivity analysis and the accept-and-reject algorithm: application to
           the cold chain of ham
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Steven Duret , Laurent Guillier , Hong-Minh Hoang , Denis Flick , Onrawee Laguerre
      Deterministic models describing heat transfer and microbial growth in the cold chain are widely studied. However, it is difficult to apply them in practice because of several variable parameters in the logistic supply chain (e.g., ambient temperature varying due to season and product residence time in refrigeration equipment), the product's characteristics (e.g., pH and water activity) and the microbial characteristics (e.g., initial microbial load and lag time). This variability can lead to different bacterial growth rates in food products and has to be considered to properly predict the consumer's exposure and identify the key parameters of the cold chain. This study proposes a new approach that combines deterministic (heat transfer) and stochastic (Monte Carlo) modeling to account for the variability in the logistic supply chain and the product's characteristics. The model generates a realistic time-temperature product history , contrary to existing modeling whose describe time-temperature profile Contrary to existing approaches that use directly a time-temperature profile, the proposed model predicts product temperature evolution from the thermostat setting and the ambient temperature. The developed methodology was applied to the cold chain of cooked ham including, the display cabinet, transport by the consumer and the domestic refrigerator, to predict the evolution of state variables, such as the temperature and the growth of Listeria monocytogenes. The impacts of the input factors were calculated and ranked. It was found that the product's time-temperature history and the initial contamination level are the main causes of consumers' exposure. Then, a refined analysis was applied, revealing the importance of consumer behaviors on Listeria monocytogenes exposure.


      PubDate: 2014-04-30T10:38:23Z
       
  • Serotype distribution and antibiotic resistance of Salmonella in
           food-producing animals in Shandong province of China, 2009 and 2012
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Jing Lai , Congming Wu , Chenbin Wu , Jing Qi , Yang Wang , Hongyu Wang , Yuqing Liu , Jianzhong Shen
      The aims of this study were to investigate the serotype distribution, genetic relationships and antibiotic resistance of Salmonella from food-producing animals in Shandong province of China in 2009 and 2012. A total of 362 out of 1825 samples from chickens, 53 out of 445 samples from ducks, and 50 out of 692 samples from pigs were positive for Salmonella. Isolates were subjected to serotyping, antibiotic susceptibility testing (15 antibiotics) and pulsed-field gel electrophoresis (PFGE). The most common serotypes recovered in the chicken samples were Enteritidis (n=294, 81.2%) and Indiana (n=45, 12.4%). For ducks, Cremieu (n=25, 47.2%), Indiana (n=13, 24.5%) and Typhimurium (n=9, 17%) were frequently isolated. In the pig samples, Derby (n=29, 58%), Typhimurium (n=9, 18%), and Enteritidis (n=6, 12%) were the most common serovars. PFGE results indicated that clonal dissemination of each serovar was prevalent, and that the Salmonella found on the poultry carcasses was caused by cross-contamination in the abattoirs. More than 99% of the Salmonella isolates collected were resistant to at least one antibiotic. The Salmonella resistance rates for 15 antibiotics in 2012 were significantly higher than those in 2009. In 2012, the highest resistance was to nalidixic acid (95.9%), followed by sulphafurazole (78.2%) and ampicillin (72.3%); the lowest levels of resistance were to kanamycin (40.1%) and amikacin (38.7%). Additionally, 41.5% and 42.2% of the Salmonella were resistant to ciprofloxacin and ceftiofur, respectively. Noticeably, 25% of the serovar Enteritidis and all of the serovar Indiana were resistant to at least 10 antibiotics in 2012. The increasing trend of antibiotic resistance in Shandong province indicates the need for more careful use of antibiotics.


      PubDate: 2014-04-30T10:38:23Z
       
  • Effectiveness of depuration for hepatitis A virus removal from mussels
           (Mytilus galloprovincialis)
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): David Polo , Cristina Álvarez , Ángeles Longa , Jesús L. Romalde
      The efficacy and kinetic of depuration of hepatitis A virus (HAV) were evaluated under experimental conditions with Mediterranean mussels (Mytilus galloprovincialis) subjected previously to bioaccumulation processes. Seven independent trials (70kg of mussels each) were performed in a closed experimental system using two different water temperatures (13 and 17°C) during 7days. The real time RT-PCR technique with TaqMan probes was used for viral quantification. Qualitative infectivity assays were conducted to test the presence of infectious viral particles at the end of the depuration period. The depuration trials showed an average reduction of HAV levels of aproximately 1.1 Log units (>90%). However, the average final viral loads in shellfish samples remain at relatively high levels (6.5×103 RNA copies/g digestive tissue) and still infectious. A positive correlation between the initial and the final numbers of the viral RNA copies was observed. The reduction of HAV showed a two-phase removal kinetic, an initial logarithmic trendline, with a rapid reduction of viruses during the first 24–48h of depuration, and a subsequent stabilization with a slower depuration rate until the end of the process.


      PubDate: 2014-04-30T10:38:23Z
       
  • Implantation and persistence of yeast inoculum in Pinot noir fermentations
           at three Canadian wineries
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Jessica N. Lange , Erin Faasse , Mansak Tantikachornkiat , Frida S. Gustafsson , Liz C. Halvorsen , Amy Kluftinger , David Ledderhof , Daniel M. Durall
      Inoculated fermentations are practiced in most wine regions of the world. This type of fermentation involves adding a commercial Saccharomyces cerevisiae strain as an inoculant. It is often assumed that the inoculant maintains dominance throughout the fermentation; however, sometimes commercial or indigenous yeasts, which were not intentionally added, end up as the dominant yeast in the winery fermentation. The aim of this study was to compare implantation/persistence of inoculants among three Canadian wineries (Quails' Gate, Cedar Creek, and Road 13 wineries). In 2010, three inoculated fermentation tanks at each of three wineries were sampled at four stages of fermentation (pre-inoculation, early, mid, and end). In addition, results from the end stage of fermentation, from two of the three wineries, were compared among different vintages (resulting in a 4-year comparison at Quails' Gate winery and a 2-year comparison at Cedar Creek winery). Strains of S. cerevisiae were discriminated by microsatellite analysis and identified using commercial microsatellite databases, whereas DNA sequencing was used to identify non-Saccharomyces. The percent implantation/persistence of the inoculum was significantly lower at Quails' Gate and Cedar Creek wineries as compared with the Road 13 winery in the 2010 vintage. Relatively low persistence of the inoculum at Quails' Gate winery was also found in the 2009 vintage, but low values were not found at Quails' Gate winery in 2011 and 2012 or at Cedar Creek winery in 2012. In all tanks having <80% relative abundance of the inoculant, the commercial strain (Lalvin ICV-D254®/Fermol® Premier Cru) was the dominant or co-dominant yeast. Our findings highlight year-to-year variation in inoculum implantation/persistence and the idea that unless strain typing of S. cerevisiae is conducted at the winery, there are no obvious fermentation factors that would indicate a relatively low inoculum implantation/persistence.


      PubDate: 2014-04-30T10:38:23Z
       
  • Development of PMA real-time PCR method to quantify viable cells of
           Pantoea agglomerans CPA-2, an antagonist to control the major postharvest
           diseases on oranges
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Lourdes Soto-Muñoz , Neus Teixidó , Josep Usall , Inmaculada Viñas , Ana Crespo-Sempere , Rosario Torres
      Dilution plating is the quantification method commonly used to estimate the population level of postharvest biocontrol agents, but this method does not permit a distinction among introduced and indigenous strains. Recently, molecular techniques based on DNA amplification such as quantitative real-time PCR (qPCR) have been successfully applied for their high strain-specific detection level. However, the ability of qPCR to distinguish viable and nonviable cells is limited. A promising strategy to avoid this issue relies on the use of nucleic acid intercalating dyes, such as propidium monoazide (PMA), as a sample pretreatment prior to the qPCR. The objective of this study was to optimize a protocol based on PMA pre-treatment samples combined with qPCR to distinguish and quantify viable cells of the biocontrol agent P. agglomerans CPA-2 applied as a postharvest treatment on orange. The efficiency of PMA-qPCR method under the established conditions (30μM PMA for 20min of incubation followed by 30min of LED light exposure) was evaluated on an orange matrix. Results showed no difference in CFU or cells counts of viable cells between PMA-qPCR and dilution plating. Samples of orange matrix inoculated with a mixture of viable/dead cells showed 5.59log10 CFU/ml by dilution plating, 8.25log10 cells/ml by qPCR, and 5.93log10 cells/ml by PMA-qPCR. Furthermore, samples inoculated with heat-killed cells were not detected by dilution plating and PMA-qPCR, while by qPCR was of 8.16log10 cells/ml. The difference in quantification cycles (Cq) among qPCR and PMA-qPCR was approximately 16cycles, which means a reduction of 65,536 fold of the dead cells detected. In conclusion, PMA-qPCR method is a suitable tool for quantify viable CPA-2 cells, which could be useful to estimate the ability of this antagonist to colonize the orange surface.


      PubDate: 2014-04-30T10:38:23Z
       
  • Decreased ethyl carbamate generation during Chinese rice wine fermentation
           by disruption of CAR1 in an industrial yeast strain
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Dianhui Wu , Xiaomin Li , Chao Shen , Jian Lu , Jian Chen , Guangfa Xie
      Saccharomyces cerevisiae metabolizes arginine to ornithine and urea during wine fermentations. In the fermentation of Chinese rice wine, yeast strains of S. cerevisiae do not fully metabolize urea, which will be secreted into the spirits and spontaneously reacts with ethanol to form ethyl carbamate, a potential carcinogenic agent for humans. To block the pathway of urea production, we genetically engineered two haploid strains to reduce the arginase (encoded by CAR1) activity, which were isolated from a diploid industrial Chinese rice wine strain. Finally the engineered haploids with opposite mating type were mated back to diploid strains, obtaining a heterozygous deletion strain (CAR1/car1) and a homozygous defect strain (car1/car1). These strains were compared to the parental industrial yeast strain in Chinese rice wine fermentations and spirit production. The strain with the homozygous CAR1 deletion showed significant reductions of urea and EC in the final spirits in comparison to the parental strain, with the concentration reductions by 86.9% and 50.5% respectively. In addition, EC accumulation was in a much lower tempo during rice wine storage. Moreover, the growth behavior and fermentation characteristics of the engineered diploid strain were similar to the parental strain.


      PubDate: 2014-04-30T10:38:23Z
       
  • Editorial Board
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179




      PubDate: 2014-04-25T11:05:19Z
       
  • Overproduction of 2-phenylethanol by industrial yeasts to improve
           organoleptic properties of bakers' products
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Rafael Dueñas-Sánchez , Ana G. Pérez , Antonio C. Codón , Tahía Benítez , Ana María Rincón
      2-Phenylethanol (PEA), an important alcohol derived from phenylalanine, is involved in aroma and flavour of bakers' products. Four spontaneous mutants of an industrial bakers' yeast, V1 strain, were isolated for their resistance to p-fluoro-DL-phenylalanine (PFP), a toxic analogue of L-phenylalanine. Mutants overproduced this amino acid and showed variations in their internal pool for several other amino acids. Moreover, a rise in PEA production after growth in industrial medium (MAB) was observed in three of the mutants, although their growth and fermentative capacities were slightly impaired. However, concentration of PEA remained higher during dough fermentation and also after baking, thus improving taste and aroma in bread.


      PubDate: 2014-04-25T11:05:19Z
       
  • Tracking and modeling norovirus transmission during mechanical slicing of
           globe tomatoes
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Y. Carol Shieh , Mary Lou Tortorello , Gregory J. Fleischman , Di Li , Donald W. Schaffner
      Recent epidemiological evidence indicates that preparation of fresh produce for use as ingredients in ready-to-eat food in commercial settings has been a significant source of the norovirus (NoV) infections in the U.S. This research investigated the dissemination of NoV from a single tomato to many others via the use of an 11-horizontal blade slicer commonly found in restaurants or sandwich shops. A total of eight trials were conducted. The source of contamination in each trial was a soak-inoculated, air-dried globe tomato containing ~8log10 murine norovirus (MNV). Each trial began by slicing a single un-inoculated tomato in the slicer, followed by slicing an inoculated tomato. This was then followed by slicing 9 to 27 un-inoculated tomatoes. A similar and constant hand pressure on the slicer was used in every trial. Three slices from each tomato were collected for virus elution, concentration, and extraction before RT-PCR detection of MNV. The change in MNV per sliced tomato was averaged over all eight trials, and two mathematical models were fit to the average data using a logarithmic model or a power model. Regression analysis determined that the equation that best fit the data was y=−0.903∗ln(x)+7.945, where y =log10 MNV per slicing and x =tomato slicing number. An acceptable fit (R 2 =0.913) was indicated. The MNV levels transferred (y) generally decreased as the number of tomatoes sliced (x) increased, with some exceptions. Infrequent but erratic transfers, where the MNV level of a subsequent tomato was higher than that of a preceding tomato, occurred in later transfer of some trials. In contrast, the first and second transfers of each trial were always shown to have sharply decreased levels of MNV from the inoculum. The MNV log10 reduction per slicing event changes throughout the process: with a predicted 0.63log10 reduction from tomato 1 to tomato 2 (76% reduction); a 0.07log10 reduction predicted from tomato 13 to tomato 14 (a 14% reduction); and 0.03log10 reduction predicted from tomato 27 to tomato 28 (a 7% reduction). Virus transfer is clearly variable even given the consistent slicing procedure used throughout each trial. This study illustrates the complex nature of risk prediction associated with NoV cross-contamination during food preparation in commercial establishments.


      PubDate: 2014-04-25T11:05:19Z
       
  • Identification of Bacillus species occurring in Kantong, an acid fermented
           seed condiment produced in Ghana
    • Abstract: Publication date: 16 June 2014
      Source:International Journal of Food Microbiology, Volume 180
      Author(s): Elmer Nayra Kpikpi , Line Thorsen , Richard Glover , Victoria Pearl Dzogbefia , Lene Jespersen
      Kantong is a condiment produced in Ghana by the spontaneous fermentation of kapok tree (Ceiba pentandra) seeds with cassava flour as an additive. Fermentation is over a 48h period followed by a drying and a kneading process. Although lactic acid bacteria (LAB) have previously been identified other micro-organisms may also be involved in the fermentation process. In this study we examined the occurrence of aerobic endospore-forming bacteria (AEB) in raw materials, during fermentation and in the final product at 2 production sites in Northern Ghana. Total aerobic mesophilic bacterial counts increased from 5.4±0.1log10 CFU/g in the raw materials to 8.9±0.1log10 CFU/g in the final products, with the AEB accounting for between 23% and 80% of the total aerobic mesophilic (TAM) counts. A total of 196 AEB were identified at a species/subspecies level by the use of phenotypic tests and genotypic methods including M13-PCR typing, 16S rRNA and gyrA gene sequencing. Bacillus subtilis subsp. subtilis (63% of the AEB), Bacillus safensis (26% of the AEB) and Bacillus amyloliquefaciens subsp. plantarum/Bacillus methylotrophicus (9% of the AEB) were the predominant Bacillus species during fermentation and in the final products. B. amyloliquefaciens/B. methylotrophicus originated from cassava flour, B. safensis from seeds and cassava flour, while the origin of B. subtilis was less clear. Brevibacillus agri and Peanibacillus spp. occurred sporadically. Further investigations are required to elucidate the role of AEB occurring in high numbers, in the fermentation of Kantong.


      PubDate: 2014-04-20T21:24:10Z
       
  • Behaviour of lactic acid bacteria populations in Pecorino di Carmasciano
           cheese samples submitted to environmental conditions prevailing in the
           gastrointestinal tract: Evaluation by means of a polyphasic approach
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Annamaria Ricciardi , Giuseppe Blaiotta , Alessandro Di Cerbo , Mariantonietta Succi , Maria Aponte
      The survival of the autochthonous microflora, of samples collected during Pecorino di Carmasciano cheese manufacturing, was evaluated along the passage through a model mimicking the gastro-intestinal tract. The aim was the selection of lactic acid bacteria potentially able to arrive alive and metabolically active to the colon. The dynamics of lactic microbiota, throughout simulated digestion of cheese samples, were evaluated by means of an approach PCR–DGGE-based. Dominant species after cheese digestion could be related to the Lactobacillus plantarum and Lactobacillus casei groups. Sixty-three strains, which survived to simulated gastro-intestinal transit, were further evaluated for technological features and tolerance to human digestion in several experimental conditions, according to routinely used protocols. Bacterial survival appeared to be, more than strain-specific, strongly affected by experimental conditions, i.e. some strains showed an acceptable survival when resuspended in skim milk but not in ewe milk and vice versa. Nevertheless according to data, one gram of fresh Pecorino di Carmasciano cheese may convey to human colon about the same amount of viable LAB of a probiotic drink. Although it cannot be assumed that lactobacilli introduced with Pecorino have beneficial effects on the host, the healthy impact of autochthonous lactic acid bacteria of naturally fermented food has a broad consensus in the current literature.


      PubDate: 2014-04-20T21:24:10Z
       
  • Evaluating food additives as antifungal agents against Monilinia
           fructicola in vitro and in hydroxypropyl methylcellulose–lipid
           composite edible coatings for plums
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Hakan Karaca , María B. Pérez-Gago , Verònica Taberner , Lluís Palou
      Common food preservative agents were evaluated in in vitro tests for their antifungal activity against Monilinia fructicola, the most economically important pathogen causing postharvest disease of stone fruits. Radial mycelial growth was measured in Petri dishes of PDA amended with three different concentrations of the agents (0.01–0.2%, v/v) after 7days of incubation at 25°C. Thirteen out of fifteen agents tested completely inhibited the radial growth of the fungus at various concentrations. Among them, ammonium carbonate, ammonium bicarbonate and sodium bicarbonate were the most effective while sodium acetate and sodium formate were the least effective. The effective agents and concentrations were tested as ingredients of hydroxypropyl methylcellulose (HPMC)–lipid edible coatings against brown rot disease on plums previously inoculated with M. fructicola (curative activity). ‘Friar’ and ‘Larry Ann’ plums were inoculated with the pathogen, coated with stable edible coatings about 24h later, and incubated at 20°C and 90% RH. Disease incidence (%) and severity (lesion diameter) were determined after 4, 6, and 8days of incubation and the ‘area under the disease progress stairs’ (AUDPS) was calculated. Coatings containing bicarbonates and parabens significantly reduced brown rot incidence in plums, but potassium sorbate, used at 1.0% in the coating formulation, was the most effective agent with a reduction rate of 28.6%. All the tested coatings reduced disease severity to some extent, but coatings containing 0.1% sodium methylparaben or sodium ethylparaben or 0.2% ammonium carbonate or ammonium bicarbonate were superior to the rest, with reduction rates of 45–50%. Overall, the results showed that most of the agents tested in this study had significant antimicrobial activity against M. fructicola and the application of selected antifungal edible coatings is a promising alternative for the control of postharvest brown rot in plums.


      PubDate: 2014-04-20T21:24:10Z
       
  • Trichothecene genotypes and production profiles of Fusarium graminearum
           isolates obtained from barley cultivated in Argentina
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Eliana Castañares , Diana Ramirez Albuquerque , María Inés Dinolfo , Virginia Fernandez Pinto , Andrea Patriarca , Sebastián Alberto Stenglein
      Fusarium graminearum is one of the most important pathogens isolated from small cereal grains with Fusarium Head Blight symptoms. The presence of this fungus is often linked to the occurrence of several mycotoxins in barley and wheat. The aim of our study was to characterize trichothecene genotypes and production profiles of F. graminearum sensu stricto isolates obtained from barley grains in Argentina. A total of 110 F. graminearum s.s. isolates were analyzed by PCR assays to predict deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON), 3-acetyldeoxynivalenol (3-ADON) and nivalenol (NIV) production, and all isolates were found to belong to the same molecular 15-ADON genotype. Trichothecene production in autoclaved rice was analyzed by using gas chromatography (GC) and confirmed by GC–MS. Of the 110 isolates, 95% were able to produce DON, 71% produced 15-ADON, 63% 3-ADON and 52% NIV. With the exception of a single isolate, all isolates that produced NIV, also produced DON. However, the NIV production was very low, ranging from 0.13 to 0.30μg/g. Six different production profiles of DON and its acetyl-derivatives were detected, the predominant being simultaneous production of DON, 3-ADON and 15-ADON, followed by DON production, and DON and 15-ADON co-production. This work is the first attempt to characterize the trichothecene genotypes and production profiles of F. graminearum s.s. isolates from Argentinean barley.


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


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


      PubDate: 2014-04-16T11:06:45Z
       
  • Array based detection of antibiotic resistance genes in Gram negative
           bacteria isolated from retail poultry meat in the UK and Ireland
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Grainne McNeece , Violetta Naughton , Martin J. Woodward , James S.G. Dooley , Patrick J. Naughton
      The use of antibiotics in birds and animals intended for human consumption within the European Union (EU) and elsewhere has been subject to regulation prohibiting the use of antimicrobials as growth promoters and the use of last resort antibiotics in an attempt to reduce the spread of multi-resistant Gram negative bacteria. Given the inexorable spread of antibiotic resistance there is an increasing need for improved monitoring of our food. Using selective media, Gram negative bacteria were isolated from retail chicken of UK-Intensively reared (n =27), Irish-Intensively reared (n =19) and UK-Free range (n =30) origin and subjected to an oligonucleotide based array system for the detection of 47 clinically relevant antibiotic resistance genes (ARGs) and two integrase genes. High incidences of β-lactamase genes were noted in all sample types, acc (67%), cmy (80%), fox (55%) and tem (40%) while chloramphenicol resistant determinants were detected in bacteria from the UK poultry portions and were absent in bacteria from the Irish samples. Denaturing Gradient Gel Electrophoresis (DGGE) was used to qualitatively analyse the Gram negative population in the samples and showed the expected diversity based on band stabbing and DNA sequencing. The array system proved to be a quick method for the detection of antibiotic resistance gene (ARG) burden within a mixed Gram negative bacterial population.


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


      PubDate: 2014-04-06T06:52:37Z
       
  • Identification and characterization of the polyketide synthase involved in
           ochratoxin A biosynthesis in Aspergillus carbonarius
    • Abstract: Publication date: 2 June 2014
      Source:International Journal of Food Microbiology, Volume 179
      Author(s): Antonia Gallo , Benjamin P. Knox , Kenneth S. Bruno , Michele Solfrizzo , Scott E. Baker , Giancarlo Perrone
      Ochratoxin A (OTA) is a potent mycotoxin produced by Aspergillus and Penicillium species and is a common contaminant of a wide variety of food commodities, with Aspergillus carbonarius being the main producer of OTA contamination in grapes and wine. The molecular structure of OTA comprises a dihydroisocoumarin ring linked to phenylalanine and, as shown in different producing fungal species, a polyketide synthase (PKS) is a component of the OTA biosynthetic pathway. Similar to observations in other filamentous ascomycetes, the genome sequence of A. carbonarius contains a large number of genes predicted to encode PKSs. In this work a pks gene identified within the putative OTA cluster of A. carbonarius, designated as AcOTApks, was inactivated and the resulting mutant strain was unable to produce OTA, confirming the role of AcOTApks in this biosynthetic pathway. AcOTApks protein is characteristic of the highly reduced (HR)-PKS family, and also contains a putative methyltransferase domain likely responsible for the addition of the methyl group to the OTA polyketide structure. AcOTApks is different from the ACpks protein that we previously described in A. carbonarius, which showed an expression profile compatible with OTA production. We performed phylogenetic analyses of the β-ketosynthase and acyl-transferase domains of the OTA PKSs that had been identified and characterized in different OTA producing fungal species. The phylogenetic results were similar for both domains analyzed and showed that OTA PKS of A. carbonarius, Aspergillus niger and Aspergillus ochraceus clustered in a monophyletic group with 100% bootstrap support suggesting a common origin, while the other OTA PKSs analyzed were phylogenetically distant. A quantitative RT-PCR assay monitored AcOTApks expression during fungal growth and concomitant production of OTA by A. carbonarius in synthetic grape medium. A clear correlation between the expression profile of AcOTApks and kinetics of OTA production was observed, with AcOTApks reaching its maximum level of transcription before OTA accumulation in mycelium reached its highest level, confirming the fact that gene transcription always precedes phenotypic production.


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


      PubDate: 2014-04-01T06:16:51Z
       
 
 
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