Engineering the oleaginous yeast Yarrowia lipolytica for β-farnesene overproduction

beta-farnesene is a sesquiterpenoid with various industrial applications which is now commercially produced by a Saccharomyces cerevisiae strain obtained by random mutagenesis and genetic engineering. We rationally designed a genetically defined Yarrowia lipolytica through recovery of L-leucine biosynthetic route, gene dosage optimization of beta-farnesene synthase and disruption of the competition pathway. The resulting beta-farnesene titer was improved from 8 to 345 mg L-1. Finally, the strategy for decreasing the lipid accumulation by individually and iteratively knocking out four acyltransferases encoding genes was adopted. The result displayed that beta-farnesene titer in the engineered strain CIBT6304 in which acyltransferases (DGA1 and DGA2) were deleted increased by 45% and reached 539 mg L-1 (88 mg g(-1) DCW). Using fed-batch fermentation, CIBT6304 could produce the highest beta-farnesene titer (22.8 g L-1) among the genetically defined strains. This study will provide the foundation of engineering Y. lipolytica to produce other terpenoids more cost-efficiently.