UNUSUAL LIPID-COMPOSITION OF THE GRAM-NEGATIVE, FRESH-WATER, STALKED BACTERIUM CAULOBACTER BACTEROIDES NP-105

The extractable lipids of the gram-negative, stalked, freshwater bacte rium Caulobacter bacteroides NP-105 account for about 9.5% by weight o f dry cells, polar lipids comprising up to 95% of the total. The polar lipids consist of five glycolipids, namely, 1,2-diacyl-3-alpha-D-gluc opyranosyl-sn-glycerol (I) (34% of the total), 2''-diacyl-sn-glycero-3 -phospho)]glucopyranosyl-sn (II) (7%), 1,2-diacyl-3-alpha-D-glucuronop yranosyl-sn-(III) (17%), l-3-alpha-D-(6'-sulfo)quinovopyranosyl-sn-gly cerol (V) (9%), and 1,2-diacyl-3-alpha-D-[4'-(alpha-D-glucopyranosyl)] glucuronopyranosyl-sn-glycerol (VI) (28%), and one glycerophospholipi d, 1,2-diacyl-sn-glycero-3-phosphoglycerol (IV) (5%), The main fatty a cyls of the lipids are n-16:0, cis-18:1 omega 7, and cis-11,12-methyle neoctadecanoic (lactobacillic) acid residue. Of the 6 lipids listed, o nly 3 (I, IV, and V) can be treated as widely encountered. However, su lfonic glycolipid V is a characteristic lipid component of photosynthe tic organisms rather than non-photosynthetic ones. Phosphatidyl deriva tives of glycosyldiacylglycerols of type II normally occur in gram-pos itive bacteria, among gram-negative bacteria they have been revealed o nly in two species of the Pseudomonas genus. Glucuronosyl and alpha-gl ucosyl-alpha-glucuronosyl diacylglycerols such as III and VI, respecti vely, are very rare lipids, the latter being found so far only in a St reptomyces strain. (C) 1997 Elsevier Science B.V.