Overexpression of Citrate-Malate Carrier Promoted Lipid Accumulation in Oleaginous Filamentous Fungus Mortierella alpina .

The mitochondrial citrate-malate carrier is responsible for the transport of citrate and malate between the mitochondria and cytosol, ensuring citrate supply substrate for fatty acid synthesis. In this study, we investigated the overexpression of the citrate-malate carrier coded by three genes ( MaCT1 / MaCT2 / MaTCT ) in Mortierella alpina to enhance lipid accumulation. Our results showed that the overexpression of MaCT1 , MaCT2 , and MaTCT increased the fatty acid content by up to 21.7, 29.5, and 12.8%, respectively, compared with the control strain, but had no effect on the growth. Among them, the MaCT2 -overexpressing strain performed the best, and its total fatty acid yield was increased by 51.6% compared to the control. Furthermore, the relative transcription level of MaCT2 indeed increased significantly in the recombinant strains. These findings are beneficial to understanding the citrate transport system and improve the industrial applications of the oleaginous filamentous fungus M. alpina .