High homogeneity of the Yersinia pestis fatty acid composition

The cellular fatty acid compositions of 29 strains of Yersinia pestis repre senting the global diversity of this species have been analyzed by gas-liqu id chromatography to investigate the extent of fatty acid polymorphism in t his microorganism. After culture standardization, all Y, pestis strains stu died displayed some major fatty acids, namely, the 12:0, 14:0, 3-OH-14:0, 1 6:0, 16:1 omega 9cis, 17:0-cyc, and 18:1 omega 9trans compounds. The fatty acid composition of the various isolates studied was extremely homogeneous (average Bousfield's coefficient, 0.94) and the subtle variations observed did not correlate with epidemiological and genetic characteristics of the s trains. Y. pestis major fatty acid compounds were analogous to those found in other Yersinia species, However, when the ratios for the 12:0/16:0 and 1 4:0/16:0 fatty acids were plotted together, the genus Yersinia could be sep arated into three clusters corresponding to (i) nonpathogenic strains and s pecies of Yersinia, (ii) pathogenic Yersinia enterocolitica isolates, and ( iii) Yersinia pseudotuberculosis and Y. pestis strains. The grouping of the two latter species into the same cluster was also demonstrated by their hi gh Bousfield's coefficients (average, 0.89), Therefore, our results indicat e that the fatty acid composition of I: pestis is highly homogeneous and ve ry close to that of Y. pseudotuberculosis.