I-11

Identification of Foodborne Bacteria Pathogens and Aerobic Endospore-Forming Bacilli Using Fatty Acid Profiles
P. Whittaker, M. M. Mossoba, S. Al-Khaldi, B. D. Tall, F. S. Fry, M. P. Yurawecz, V. C. Dunkel, CFSAN, FDA, College Park, MD

A gas chromatographic (GC) analysis method was used 1) to determine the cellular fatty acid profiles of various foodborne microbial pathogens, and 2) to compare the fatty acid profiles of spores and vegetative cells of the same endospore-forming bacilli. Fifteen different bacteria, representing 8 genera (Staphylococcus, Listeria, Bacillus, Yersinia, Salmonella, Shigella, Escherichia, and Vibrio) and 11 species, were used to prepare the bacterial fatty acid methyl esters (FAMEs). The endospore-forming bacilli were processed to obtain pure spores and whole cell FAMEs for GC analysis. The cells were cultured on brain heart infusion agar at 35°EC for 24 hours, harvested and then subjected to saponification, methylation and extraction into hexane:methyl tert-butyl ether. The bacterial FAMEs were then measured by GC. A database for each bacterial agent was prepared using fatty acid profiles from 5 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 B. anthracis and B. cereus show that there are two fatty acids, iso 17:1 w10c and 17:1 anteiso, that are unique in these species. Iso 17:1 w10c 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, this analytical method provides a procedure for the identification of bacteria and spores based on their unique fatty acids.
2004 FDA Science Forum | FDA Chapter, Sigma Xi | CFSAN | FDA
Last updated on 2004-APR-02 by frf