The Lipid Fatty Acids of Proteolytic Clostridia

Abstract

Capillary gas-liquid chromatography (g.l.c.) and g.l.c./mass spectrometry (g.l.c./m.s.) were used to study the fatty acid composition of the lipids of the following 23 species of proteolytic clostridia grown in a Trypticase/yeast extract medium: Clostridium bifermentans, C. cadaveris, C. caloritolerans, C. cochlearium, C. difficile, C. ghoni, C. glycolicum, C. histolyticum, C. lentoputrescens, C. limosum, C. lituseburense, C. malenominatum, C. mangenotii, C. propionicum, C. putrefaciens, C. putrificum, C. scatologenes, C. sordellii, C. sporogenes, C. sticklandii, C. subterminale, C. tetani, C. tetanomorphum. These species contained a total of 55 fatty acids in the range C12 to C18. The methyl esters were separated on a 152 m stainless steel capillary column coated with poly(1,4-butanediol succinate) and characterized by their equivalent chain lengths and by g.l.c./m.s. The predominant acids were n-C14:0 and n-C16:0. There were two groups of organisms: those which contained fatty acids of the n, iso and anteiso series and those which contained only those of the n series. All the organisms which contained iso and anteiso acids also oxidized valine, leucine and isoleucine to the corresponding branched-chain volatile fatty acids. The iso acids found had both even and odd numbers of carbon atoms and were probably derived from valine and leucine, respectively; the anteiso acids all had odd numbers of carbon atoms and were probably derived from isoleucine via 2-methylbutyric acid. These organisms also produced small amounts of monoenoic iso acids. Of the seven species which contained only acids of the n series, C. histolyticum produces acetic acid as its only end-product whereas the other six ferment glutamic acid and produce acetic and n-butyric acids; they also form propionic acid from threonine.