The major phospholipids of two strains of Bdellovibrio bacteriovorus were characterized. Both strain UKil, which is obligately saprophytic, and strain UKi2, which is facultatively parasitic, contained phosphatidylethanolamine and phosphatidylglycerol as their major glycerophosphatides. A branched, 15-carbon fatty acid is the major component of these alkali-labile lipids. Absent from UKil but present in UKi2 were three alkali-stable lipids (compounds 8, 9, and 11) which appear to be phosphosphingolipids. After acid hydrolysis, both compound 8 and 9 yield the identical phosphorus-containing substance that is water soluble, dipolar ionic, and ninhydrin positive. This substance appears to contain a C-P bond since P1 could not be released from this substance by treatment with alkaline phosphatase or by very harsh mineral acid treatment. Based on chromatographic comparisons, this phosphonate appears to be a novel lipid constituent. Upon degradation, compound 8 yields 1 mol of dihydroxy long-chain base and compound 9 yields 1 mol of a trihydroxy long-chain base. These bases appear to have a 17-carbon, possibly branched, structure based on gas-liquid chromatography retention times. Degradation of both sphingolipids yields a mixture of hydroxy fatty acids, the major component being a branched, 15-carbon hydroxy acid.
1971).MATERIALS AND METHODS Growth of bacteria. B. bacteriovorus strains UKil and UKi2 (4) were grown on 1% (wt/vol) peptone-0.3% (wt/vol) yeast extract on a rotary shaker at 30 C for 15 h. In some experiments the medium was supplemented with "2P-orthophosphate (carrier-free, New England Nuclear Corp., or ICN Corp.).Extraction of lipid. The phospholipids were extracted according to a modification of the method of Lester and Steiner (17). '2P-lieled cells were harvested from 25 ml of medium by centrifugation and suspended in 1.0 ml of water. A 5-ml amount of (CH2CH2)20-CH,CH2OH (3:1, vol/vol) was added, on July 16, 2020 by guest