Deletion of the Fatty Acid Synthase Gene Enhanced Lipid Accumulation in the Oleaginous Fungus Mucor circinelloides WJ11

Two fas genes (namely fas1 and fas2 ) of Mucor circinelloides WJ11 were deleted through homologous recombination technology. The deletion of the fas gene has a considerable influence on lipid content and fatty acid composition. Compared with the control strain, the lipid content at fermentation of 96 h was increased by 9.1% for the fas1 -knockout strain Mc- fas1 Δ and 18.4% for the fas2 -knockout strain Mc- fas2 Δ, respectively. Possibly due to the compensatory effect between fas1 and fas2, the expression of fas2 was improved 4.3-fold in Mc- fas1 Δ compared with the control strain, and that of fas1 was significantly improved 14.3-fold in Mc- fas2 Δ, aligning with the elevated FAS activity in both mutant strains. Meanwhile, the deletion of the fas gene also drives the enzymatic activity and gene expression of key enzymes that provide substrates and reducing power for fatty acid synthesis. This is the first report demonstrating the correlation between the fas gene and lipid synthesis in the oleaginous fungus M. circinelloides .