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United States Department of Agriculture

Agricultural Research Service

Research Project: INTERVENTION TECHNOLOGIES FOR MINIMALLY PROCESSED FOODS

Location: Food Safety and Intervention Technologies

Title: Potential for bio-control of food-borne pathogens with Bacteriovorax spp. and implications for food safety

Authors
item Olanya, Modesto
item Richards, Gary

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 17, 2014
Publication Date: July 21, 2014
Citation: Olanya, O.M., Richards, G.P. 2014. Potential for bio-control of food-borne pathogens with Bacteriovorax spp. and implications for food safety. Meeting Abstract. Proceedings of the 3rd International Conference and Exhibition on Food Processing and Technology. Las Vegas, Nevada. 2014. Volume 5: Page 47.

Technical Abstract: Bacteriovorax spp. (Bvx) are delta proteobacteria adapted to marine ecosystems where salinity concentration range from 1-3%. Due to their predation of Gram-negative bacteria, Bvx may have great potential for biocontrol of food-borne pathogens on fruits and leafy greens. The goal of this research was to optimize the plaque assay for quantifying Bvx isolates. We determined the predation of E. coli O157:H7 (Ec) and formation of Bvx plaques by Bvx strains G3, S11, OR7, and OS1 on polypeptone peptone medium (PP20) amended with sterilized seawater (SW) in a double agar plaque assay. For plaque assays of Bvx, bottom and top PP20 agar layers were amended with: a) NaCl (bottom layer)+SW (top layer), b) SW (bottom)+NaCl (top), c) SW (bottom)+SW (top), and d) NaCl-MgCl-CaCl (bottom)+NaCl (top) and plaques were enumerated on Ec host cells. The effects of incubation temperatures (22, 26, 31, 37 deg C) on plaque development were assessed on lawns of Ec. Plaque forming units (PFU/ml) on PP20 amended with SW ranged from 0.56 x 10e6 (OR7) to 2.07 x 10e6 (isolate S11). PP20 amended with NaCl and divalent calcium and magnesium had the lowest mean number of plaques (0.73 x 10e6 PFU/ml), while SW+NaCl (1.22 x 10e6) had the greatest counts. Except for G3, storage temperatures varied with Bvx, as temperature optima for OR7 and S11 was 26 deg C, but were non-significant (P>0.05) for G3. These results suggest that food-borne pathogens and Bvx may be assessed on PP20 devoid of SW, which could otherwise provide a source of variability from one seawater collection to another. Storage temperatures and media amendment provide useful parameters for quantifying Bacteriovorax efficacy as a biocontrol agent.

Last Modified: 11/25/2014
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