Use of a rapid analytical method for identifying closely related Yersinia species to provide a procedure for food safety and security

Abstract

Capillary gas chromatography with flame ionization detection (GC‐FID) analysis of chemical components of bacterial cells has provided useful information for rapid detection and identification of bacteria in clinical and diagnostic bacteriology laboratories and currently has increased significance for both food safety and security. GC‐FID was used to determine the cellular fatty acid (CFA) profiles of closely related Yersinia species. For GC‐FID analysis, whole cell fatty acid methyl esters (FAMEs) from cells cultured on brain heart infusion (BHI) agar at 35 (C for 24 h were obtained by saponification, methylation and extraction into hexane/methyl tert‐butyl ether. A data set for each Yersinia species was prepared using fatty acid profiles from five replicates prepared on different days. Major fatty acids of the 26 Yersinia strains evaluated in this study were straight‐chain 12:0, 14:0, 15:0, 16:0 and unsaturated 16:1 ω7c/16:1 ω6c, 18:1 ω7c, and 14:0 3OH/16:1 iso, and 17:0 ωcyclo 7‐8. The Yersinia species Y. enterocolitica, Y. pseudotuberculosis, Y. frederiksenii, Y. intermedii, Y. kristensenii, and Y. pestis have unique fatty acid patterns. The CFA profiles for Y. pestis and Y. pseudotuberculosis are similar, but there are several fatty acids, 16:1 ω5c, 16:0, 17:1 ω7c, 17:0 ωcyclo 7‐8, 19:0 and summed 18:2 ω6c, 9c/18:0 ante that differ significantly between these two species. Analysis of FAMEs from Yersinia strains grown on BHI agar by a rapid GC‐FID method can provide a sensitive procedure for the identification of these organisms, and this analytical method provides a procedure applicable to issues of both food safety and security.