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Hydrophobic Extraction of B. anthracis Spores from Liquid Foods

Award No.: 
Principal Investigator: 
Francisco Diez-Gonzalez
PI Organization: 
University of Minnesota-Twin Cities
The lack of effective pre-analytical methods for quick recovery of select agents in foods is a major weakness of our national food security system. Milk and other liquid foods that are potential targets for bio-terrorist attack with a number of select agents, including Bacillus anthracis. The purpose of this study was to investigate methods of extracting and concentrating B. anthracis from milk based on hydrophobicity and density differences. Raw milk inoculated with specific levels of spores was subjected to heat, centrifuge treatments, and hexadecane to determine concentration efficiency. Inoculated milk was also centrifuged with and without a silicone oil layer of greater density than milk. Spores were effectively concentrated and extracted (> 90% recovery) from inoculated raw milk when first heated at 85°C for 60 s, then centrifuged with silicone oil. A low percentage of spores were recoverable from milk that had not being heated prior to centrifugation. Few spores were recovered from extraction with milk using hexadecane. Spore concentration increased in the cream phase following separation. This data suggests that it is possible to rapidly and effectively concentrate and extract spores from milk.