IAFP 2009 Program Book and Abstract Book - AB186

Results: When selected foods were inoculated with Salmonella serovars at a level of ~1 CFU/25 g, there was no difference in sensitivity between this method and the standard reference methods. When specificity was evaluated 96/100 Salmonella serovars were identified using this method, and 29/30 of the non-Salmonella showed no growth or atypical growth. Significance: Enriching samples using ONE Broth Salmonella and plating on Brilliance™ Salmonella medium reduced time to detection to 2 days, compared to 4 days for the FDA and USDA methods. P3-103 Purification and Characterization of Xylanase from a New Strain of Bacillus sp. LI-JUNG YIN, Yen-I Chiang and Shann-Tzong Jiang National Kaohsiung Marine University, Dept. of Sea Food Science, Kaohsiung, Taiwan Introduction: Xylo-oligosaccharides are non-carcinogenic and considered to be prebiotics that can promote the growth of beneficial bifidobacteria in the colon. They are sugar oligomers produced during hydrolysis of xylan, a major component of plant hemicellulose. Xylanases are glycosidases that can catalyze the endohydrolysis of 1,4-β-D-xylosidic linkages in xylan. Purpose: The aim of this study was to purify and characterize xylanase produced by a new strain Bacillus sp. grown on rice straw. Methods: The cells of Bacillus sp. were removed by passing through a 0.45 µm membrane after 4 days incubation at 25°C which had the highest xylanase activity (2.26 U/mL). Purification procedures included ammonium sulfate precipitation, ion exchange and gel filtration chromatographs. Results: The xylanase was purified to electrophorectical homogeneity by precipitating at 40 to 60% saturation of ammonium sulphate, passing through CM-Sepharose FF and Sephacryl S-100 HR chromatographs. About 3.5% of xylanase was recovered and 678.1-fold purification was obtained. The purified xylanase was with a molecular mass of 19 kDa and specific activity of 1435.98 U/mg. It had an optimal pH and temperature at 6.0 and 50°C, respectively, and was stable at pH 5.0~9.0 and 10~40oC. This xylanase was highly inhibited by Cu2+, Fe3+, Hg2+, PMSF, TPCK, NEM and Leupeptin, but strongly activated by β-mercaptoethanol and glutathione. Significance: According to substrate specificity, the purified xylanase had high specificity to beechwood xylan, birchwood xylan and oat spelts xylan. From the above substrate specificity suggests the potential use of the purified xylanase in xylooligosaccharide production. P3-104 Survival of Escherichia coli O157:H7 and Salmonella Newport in Animal Feces SADHANA RAVISHANKAR, Libin Zhu and Jorge M. Fonseca University of Arizona, Veterinary Science & Microbiology, Tucson, AZ, USA Introduction: Human enteric pathogens can be shed in animal feces, which in turn could serve as the primary source for contamination of vegetables in the field. Escherichia coli O157:H7 and Salmonella enterica are well known to survive in animal feces. The survival of these pathogens in animal feces shed in vegetable fields can be affected by several factors, including relative humidity (RH) and temperature. Purpose: The objective of this study was to determine the growth and/or survival of E. coli O157:H7 and S. enterica serotype Newport in different animal feces exposed to various temperatures and RH levels. Methods: Cow and dog feces were inoculated with E. coli O157:H7 or S. Newport overnight culture (10M7 CFU/g). Samples were stored at either 26°C, 40% RH or 15°C, 80% RH. Surviving populations of E. coli O157:H7 and S. Newport were enumerated by taking samples at different times, stomaching, diluting, and plating on appropriate media. Results: In dog feces, both E. coli O157:H7 and S. Newport survived longer at 15°C, 80% RH than at 26°C, 40% RH. Both pathogens survived up to 7 days at 15°C, while the survival was only 3 days at 26°C. With one batch of cow feces, the survival of E. coli O157:H7 was 103 CFU/g on day 370 at 26°C, and 102 CFU/g on day 373 at 15°C. The survival of S. Newport was 102 CFU/g on day 289 at 15°C, as well as on day 284 at 26°C. In another batch of cow feces, for both pathogens, no survivors were detected on day 180 at 15°C, but both pathogens survived longer than 230 days (102 CFU/g) at 26°C. Significance: This study will provide the produce industry with a good scientific basis to understand pathogen survival in animal feces under different conditions, which can in turn contribute to mitigating microbiological risks from contaminated vegetables. P3-105 Recovery and Infectivity of Norovirus in Bacterial Biofilms on Stainless Steel ADRIENNE E. SHEARER and Kalmia E. Kniel University of Delaware, Animal and Food Sciences, Newark, DE, USA Introduction: Recurring outbreaks of norovirus infection have occurred among individuals in close association despite reported fervent cleaning of common contact surfaces. The persistence of hepatitis A virus and bacteriophage in bacterial aggregations in food and drinking water systems, respectively, has been observed. The persistence of norovirus in biofilms has not been reported. Purpose: The incorporation and infectivity of mouse norovirus (MNV-1), as a surrogate for human norovirus, was assessed on material commonly found in food handling environments. Methods: Duplicate stainless steel (type 304, 16-gauge) coupons (1 in by 3 in) were suspended in 25 ml deionized water with MNV-1 (104 PFU/ml) alone or in a cocktail of Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli (3 × 107 CFU/ml combined) added either simultaneously or 6 h prior to the addition of virus. Inoculated coupons were incubated unagitated at ambient temperature for 48 h. Coupons were rinsed in deionized water stream (20 ml), then shaken vigorously (30 s) in 25 ml of Butterfield’s Phosphate Buffer (BPB). Bacteria recovered in BPB were enumerated on TSA. BPB was centrifuged to pellet bacteria, and infectivity of MNV-1 in the supernatant was determined by plaque assay in RAW cells. The efficacy of Virkon® (0.1 g/mL, 10-minute submersion) disinfection on coupons was evaluated. Poster 186 — Abstract Book

IAFP 2009 Program Book and Abstract Book

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