Docosahexaenoic acid (DHA) is an essential dietary supplement that is highly coveted due to its benefits for human health. Extensive research has been conducted for the sustainable commercial production of DHA by various strains in thraustochytrid family due to the accumulation of higher lipid content in the cells. The current study is focused on improving DHA production by investigating various key enzymes like glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME), and ATP-citrate lyase (ACL) involved in DHA production using Thraustochytrium sp. T01. The growth of this strain was compared in batch and fed-batch mode. The fed-batch yielded better Dry cell weight (40 g L-1), lipid (27.75 g L-1 or 693 mg g-1 of DCW), and DHA contents (11.10 g L-1 or 277 mg g-1 of DCW). G6PDH activity increased 4-fold during the glucose fed-batch, but ME and ACL did not increase significantly. Furthermore, a study was conducted to determine the effects of organic acids (pyruvate and malate) on key enzyme activities. The addition of pyruvate increased the lipid content by 1.35-fold, and ACL activity by 10-fold as compared with control (without added organic acids). Malate addition into the culture media increased DHA content 1.4-fold, and ME activity increased 14-fold compared with control.
Keywords: ATP-citrate lyase; Acetyl CoA; docosahexaenoic acid; glucose-6-phosphate dehydrogenase; malic enzyme.