Nitrogen Sources Affect the Long-Chain Polyunsaturated Fatty Acids Content in Thraustochytrium sp. RT2316-16

The psychrophilic marine microorganism Thraustochytrium sp. RT2316-16 can produce carotenoids as well as lipids containing the omega-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid and docosahexaenoic acid. This work reports on the effects of the composition of the culture medium, including certain amino acids, on growth and lipid synthesis by RT2316-16. Compared with the culture on glutamate, the use of lysine, alanine, or serine, increased the content of the omega-3 PUFA in total lipids. In the media that contained yeast extract, glutamate, and glucose, lipid accumulation occurred when organic ammonium was exhausted earlier than glucose. In contrast, lipid mobilization was promoted if glucose was exhausted while organic ammonium (supplied by yeast extract and glutamate) remained in the medium. The total content of carotenoids in the lipid-free biomass decreased during the first 12 to 24 h of culture, simultaneously with a decrease in the total lipid content of the biomass. The experimental data suggested a possible interrelationship between the metabolism of carotenoids and lipids. A high content of omega-3 PUFA in the total lipids could be obtained by growing the thraustochytrid in a medium with a low glucose concentration (6 g L-1) and a high concentration of organic nitrogen (yeast extract 12 g L-1; glutamate 1.06 g L-1), after glucose was exhausted. These observations may guide the development of a strategy to enhance omega-3 PUFA in the biomass.

Automated summary

This study investigates the effects of different amino acids in the culture medium on the growth and lipid synthesis of Thraustochytrium sp. RT2316-16. The results show that lysine, alanine, or serine can increase the content of omega-3 polyunsaturated fatty acids (PUFA) in the lipids. The use of organic ammonium and glucose in the culture medium also affects lipid accumulation and mobilization. The findings suggest a possible relationship between carotenoid and lipid metabolism, and provide guidance for enhancing omega-3 PUFA in the biomass.