LIPID STORAGE COMPOUNDS IN MARINE-BACTERIA

Forty psychrophile or psychrotrophic crude-oil-utilizing marine bacter ia were investigated for their ability to accumulate lipid storage com pounds in the cytoplasm during cultivation under nitrogen-limiting con ditions. Most of them (73%) were able to accumulate specialized lipids like polyhydroxyalkanoic acids (PHA) while other lipids such as wax e sters occurred in two isolates. Accumulation of PHA occurred predomina ntly at low temperatures (4-20 degrees C) as demonstrated for three is olates. Electron microscopy revealed polyphosphate inclusions occurrin g in two isolates in addition to PHA. Cells of the isolate Acinetobact er sp. 211 were able to synthesize and accumulate lipid inclusions dur ing growth on acetate, ethanol, olive oil, hexadecanol and heptadecane . The composition of the lipid inclusions depended on the compounds pr ovided as carbon source. Wax esters and acylglycerols occurred mainly during the cultivation on olive oil; in contrast, wax esters and free alcohols occurred during cultivation on hexadecanol. Total fatty acids in cells of the Acinetobacter sp. 211 amounted to 25% of the cellular dry weight in olive-oil-grown cells. Palmitic acid was the main fatty acid in the lipids when the cells were cultivated on acetate or ethan ol (44% and 32% of total fatty acids respectively). In contrast, fatty acids occurring in the lipids during cultivation on hexadecanol, hept adecane or olive oil were related to the carbon source. The fatty acid s present in the accumulated lipids consisted predominantly of saturat ed and unsaturated straight-chain fatty acids with a chain length rang ing from 12 to 18 carbon atoms. Analysis of the lipid-granule-associat ed proteins in cells of Acinetobacter sp. 211 revealed a protein of 39 kDa as the predominant protein species.