FATTY ACID COMPOSITION OF WHOLE CELLS THYLAKOIDS AND LIPOPOLYSACCHARIDES OF RHODOSPIRILLUM RUBRUM AND RHODOPSEUDOMONAS CAPSULATA

The fatty acid composition of the photosynthetic bacteria Rhodospirillum rubrum and Rhodopseudomonas capsulata was investigated. The bulk of fatty acids of R. rubrum consisted of C16:0 (11%), C16:1 (30%), and C18:1 (52%). The major fatty acid of Rps. capsulata was vaccenic acid (C18:1), which accounted for 94% of the total fatty acids. Cells of both organisms, which were grown anaerobically in the light and fitted out with thylakoids had the same fatty acid composition as cells grown aerobically in the dark, which have no thylakoids. Purified thylakoids had the same fatty acid pattern as whole cells. Whole cells of light and dark cultures were extracted with phenol/water at 68° C. An opalizing fraction in the aqueous phase was sedimentable in the ultracentrifuge like the lipopolysaccharides of the Enterobacteriaceae. The pattern of fatty acids in this compound differed considerably from that of whole cells. The major fatty acids in this macromolecular fraction were C12:1 (40%) and C16:0 (50%) in Rps. capsulata, whereas in R. rubrum the whole range of fatty acids from C10 to C20 was demonstrable. Light and dark grown cells differed in the fatty acid composition of that compound. The fatty acid content of the extracted fraction accounted for 5-7% of the total fatty acids of whole cells. No hydroxymyristic acid could be identified in either R. rubrum or Rps. capsulata. © 1969 Springer-Verlag.