Effect of pyridine on the fatty acid composition of Pimelobacter sp.

Abstract The fatty acid composition of Pimelobacter sp. is of the complex type. When pyridine was used as a sole inhibitory substrate, the fatty acid composition of Pimelobacter sp. was quite different from that within other readily available substrates. When compared with the fatty acid composition in a complex medium, the proportion of isopalmitic acid ( iso -C_16:0) drastically decreased from 68.4% to 7.7%, while the proportion of anteisoheptadecanoic acid ( anteiso -C_17:0) remained almost constant at ca. 7%. Concomitantly, this decrease of the branched-chain fatty acid was accompanied by the increase of the straight-chain, especially long-chain, fatty acid such as heptadecanoic (C_17:0), octadecenoic (Cig:i), 10-methylheptadecanoic (10-me-18) and 10-methyloctadecanoic (10-me-19) acids. Consequently, in response to membrane active organic solvents, Pimelobacter sp. was found to regulate its membrane fatty acid composition in a fashion different from Gram-negative bacteria.