Improving an Alternative Glycerol Catabolism Pathway in Yarrowia lipolytica to Enhance Erythritol Production

Engineering the glycerol-3-phosphate pathway could enhance erythritol production by accelerating glycerol uptake. However, little work has been conducted on the alternative dihydroxyacetone (DHA) pathway in Yarrowia lipolytica. Herein, this route was identified and characterized in Y. lipolytica by metabolomic and transcriptomic analysis. Moreover, the reaction catalyzed by dihydroxyacetone kinase encoded by dak2 was identified as the rate-limiting step. By combining NHEJ-mediated insertion mutagenesis with a push-and-pull strategy, Y. lipolytica strains with high-yield erythritol synthesis from glycerol were obtained. Screening of a library of insertion mutants allows the identification of a mutant with fourfold increased erythritol production. Overexpression of DAK2 and glycerol dehydrogenase GCY3 together with gene encoding transketolase and transaldolase from the nonoxidative part of the pentose phosphate pathway led to a strain with further increased productivity with a titer of 53.1 g/L and a yield 0.56 g/g glycerol, which were 8.1- and 4.2-fold of starting strain.