Incorporation of exogenous docosahexaenoic acid into various bacterial phospholipids

Incorporation of exogenous docosahexaenoic acid (DHA) into bacterial phospholipids was examined as a method for DHA-linked phospholipid production. The cultivation of 23 bacterial strains in medium with DHA showed that an eicosapentaenoic acid-producing bacterium Shewanella sp. strain SCRC-2738 (strain SCRC-2738), Bacillus subtilis W23, B. cereus, an Antarctic marine bacterium strain S-7 (strain S-7), photosynthesis bacterium (PSB) Rhodopseudomonas capsulatus utilized for the production of larval marine fish, Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens and Escherichia coli K12 all incorporated DHA into their polar lipids. The polar lipids of the strain SCRC-2738, strain S-7, PSB and E. coli K12 were identified to be phospholipids. DHA was localized at the sn-2 position in the phospholipids of the four strains. Incorporation of exogenous DHA into their phospholipids produced an increase in saturated fatty acids and a decrease in monounsaturated fatty acids except E. coli K12. The strain SCRC-2738 incorporated the largest amount of DHA into their phospholipids among the tested bacterial strains in this study: DHA was 16% of the total fatty acids in the phosphatidylethanolamine (PE) and 29% in the phosphatidylglycerol (PG). In the PSB, incorporated DHA was 12% of the total fatty acids in the PE, 10% in the PG and phosophatidylcholine so that the PSB was nutritionally fortified.