Use of fatty acid profiles to identify food-borne bacterial pathogens and aerobic endospore-forming bacilli.

Capillary gas chromatography (GC) with flame ionization detection was used to determine the cellular fatty acid profiles of various food-borne microbial pathogens and to compare the fatty acid profiles of spores and vegetative cells of the same endospore-forming bacilli. Fifteen bacteria, representing eight genera (Staphylococcus, Listeria, Bacillus, Yersinia, Salmonella, Shigella, Escherichia, and Vibrio) and 11 species were used to compare the extracted fatty acid methyl esters (FAMEs). Endospore-forming bacilli were processed to obtain pure spores and whole cell FAMEs for GC analysis. A data set for each bacterial agent was prepared using fatty acid profiles from five replicates prepared on different days. The results showed that these fatty acid intensity profiles were unique for each of the 11 species and that they could be used as a fingerprint for the organisms. The cellular fatty acid profiles for Bacillus anthracis and Bacillus cereus show that there are two branched chain fatty acids, iso 17:1 omega10c and 17:1 anteiso, which are unique in these species. Iso 17:1 omega10c is present in B. cereus vegetative cells and spores but is not observed in B. anthracis. The 17:1 anteiso fatty acid is present in B. anthracis cells but not in B. cereus cells. Fatty acids 16:0 2OH and 17:0 iso 3OH are present in B. anthracis and B. cereus spores but not in the vegetative cells. In summary, analysis of FAMEs from bacteria and spores can provide a sensitive procedure for the identification of food-borne pathogens.