IAFP 2009 Program Book and Abstract Book - AB174

lactate and nitrite), either alone or in combination with reduced pH (5.5) and added salts (sodium chloride and potassium chloride). Studies were done in a broth system and a cooked sliced chicken product. Two types of C. botulinum cocktail were used, one containing non-proteolytic type B and one containing type E. Results: Results showed that in the broth system, reduction of the pH to 5.5 had the largest antibotulinal effect at either 8° or 30°C. Additional effects were observed by addition of any of the four preservative types, particularly at 30°C, where pH reduction alone was not sufficient to inhibit growth. In the sliced cooked chicken product, the presence of any of the four preservatives inhibited the growth of C. botulinum over a four-week period, in contrast to growth in the control chicken, in which growth of this organism occurred within 3 weeks. Furthermore, the levels of C. botulinum type E declined in products containing nitrite and lactate. Significance: This study has demonstrated the potential for use of benzoate, lactate, sorbate and nitrite as antibotulinal agents in chilled VP/MAP foods. P3-69 Bacteriophages to Control Foodborne Pathogens in Ready-to-Eat Meat HANY E. ANANY, Isabelle Gross and Mansel Griffiths University of Guelph, Canadian Research Institute for Food Safety, Guelph, ON, Canada Introduction: Bacteriophages have potential for the control of foodborne pathogens. It was shown previously that bacteriophage can reduce the number of many pathogens, either in laboratory media or in foods. Purpose: Therefore, our objective is to develop systems based on host-specific bacteriophage to enhance food safety by capturing and controlling some important foodborne pathogens in food matrices. Methods: A cocktail of three lytic bacteriophages active against each of E. coli O157:H7, Salmonella Enteritidis, Listeria monocytogenes and Shigella boydii were tested in TSB at 4 and 25°C. The Bioscreen C was used to determine the most effective multiplicity of infection (MOI) for each cocktail to control its respective host over a five day incubation period at 25°C. Listeria phages have been tested for their ability to control Listeria monocytogenes in Ready-to-Eat oven roasted turkey under different packaging (aerobic, anaerobic and MAP) conditions and temperatures (4° and 25°C). Results: Results showed that cocktails of phage were able to reduce bacterial growth by 1 to 2.6 log cycles at 4°C, while at 25°C reductions were from 2 to 7 logs. For the Salmonella at 25°C, the difference between control and treated samples was not noticeable. The Bioscreen results showed that a MOI higher than 0.1 was sufficient to inhibit growth of Listeria monocytogenes, while MOI of around 103 to 105 was required to cause complete growth inhibition for the other target pathogens. Furthermore, the Listeria phage cocktail led to reductions in count of Listeria monocytogenes of between 1 to 2.2 log cycles in the meat at different storage conditions. Significance: These findings suggest that using a cocktail of lytic bacteriophages is a useful biocontrol option that can be used alone or in combination with other preservation techniques to enhance food safety. P3-70 Control and Prevention of Cronobacter sakazakii and S. enterica Typhimurium by Each Virulent Phage in Powdered Infant Formula YOUNG-DUCK LEE, Young-Duck Lee, Tae-Hwa Ryu, Hyo-Ihl Chang and Jong-Hyun Park Korea University, Seoul, Korea, South Introduction: Cronobacter sakazakii (Enterobacter sakazakii) and S. enterica Typhimurium are major foodborne pathogens in powdered infant formula (PIF). Especially, these pathogens can lead to serious developmental effects and death in infants. Purpose: The aims of this study were reduction of C. sakazakii and S. enterica Typhimurium by using virulent phages in PIF. Methods: Phages were isolated from swine feces and analyzed plaque assay, transmission electron microscopy, DNA restriction enzyme patterns and structure protein profiles. Results: As the results of screening, seven C. sakazakii phages (CS) and five S. enterica Typhimurium (ST) phages were newly isolated. Bacterial cell lytic activity was dependent on infection temperature and concentration of each phage. Each virulent phage was selected for further testing for infection efficiency. CS2 and ST2 phage effectively prevented growth of target pathogens in culture broth and powdered infant formula at various temperatures. Significance: In conclusion, we think that use of the virulent phages might be reduce the risk of C. sakazakii and S. enterica Typhimurium infection in PIF. P3-71 Isolation and Identification of Bacteriophages against Salmonella Typhimurium MASTURA AKHTAR, Stelios Viazis, Joellen Feirtag and Francisco Diez-Gonzalez University of Minnesota, Food Science and Nutrition, St. Paul, MN, USA Introduction: Salmonella is one of the most common causes of enteric foodborne infections. Among all Salmonella serovars, S. Typhimurium is responsible for the majority of human cases. Purpose: The goal of this project was to develop a collection of bacteriophages isolated from manure specific against Salmonella. Specific objectives included isolation, identification, characterization and evaluation of phages for controlling Salmonella Typhimurium. Methods: Animal waste samples were collected from a dairy cattle herd and a swine barn. The bacteriophage isolation method included enrichment, spot test, filtration, plaque assays, purification and amplification. Salmonella Typhimurium strains were used as host strains in the isolation process. Isolated phages were tested against pure cultures of different Salmonella strains including Typhimurium, Newport, Montevideo, Agona, Enteritidis and Heidelberg serovars. The efficiency of plaquing (EOP) method was used to measure lytic activity of phages. Some phages were tested against Escherichia coli O157:H7 strains to evaluate the broad spectrum activity. Transmission electron microscopy (TEM) was used to observe phage morphology. 174 — Abstract Book Poster

IAFP 2009 Program Book and Abstract Book

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