INTRASPECIES VARIABILITY OF CELLULAR FATTY-ACIDS AMONG SOIL AND INTESTINAL STRAINS OF DESULFOVIBRIO-DESULFURICANS

A comparison of cellular fatty acid profiles of Desulfovibrio desulfur icans DSM 642 and 14 wild strains of this species, isolated from two c ompletely different environments, soil and the human intestine, was ca rried out, All the D. desulfuricans strains grown on lactate and sulfa te indicated the presence of considerable amounts of i-C-15:0, i-C-17: 1 and C-16:0. Although differences in the quantities of individual fat ty acids present in each strain were clear in the group of soil strain s (similarity, 67.6%), in contrast to almost identical fatty acid patt erns (similarity, near 100%) in the intestinal strains, the results we re variable within the limits acceptable for species demonstration, Th e higher similarity of the fatty acid profiles of intestinal strains m ay be a result of the similarity of biocenoses in the human digestive tract. The coefficients of variability of i-C-17:1 and i-C-15:0 (the m ajor branched-chain fatty acids), as well as clustering of the investi gated strains compared with strains described in the literature after plotting percentages of i-C-17:1 fatty acid against i-C-15:0 fatty aci d, confirmed a certain heterogeneity of cellular fatty acid profiles w ithin the group of soil strains, in contrast to almost ideal homogenei ty within the group of intestinal isolates. Intestinal strains contain ed a higher ratio of saturated to unsaturated fatty acids (2.2 +/- 0.1 4) than did soil strains (1.6 +/- 0.2; in one case, 2.7), We propose t hat intestinal D. desulfovibrio bacteria should be assumed to be a hig hly homogeneous group and should be represented by the strain D. desul furicans subsp, intestinus in collections of microbial cultures.