Efficient D-threitol production by an engineered strain of Yarrowia lipolytica overexpressing xylitol dehydrogenase gene from Scheffersomyces stipitis

Abstract

D-threitol (hereinafter as threitol) is a diastereoisomer of erythritol with wider applications in green chemistry, food, pharmaceutical, and medicine. Herein, xylitol dehydrogenase from Scheffersomyces stipitis CBS 6054 was demonstrated able to catalyze highly efficient threitol formation from erythritol with erythrulose as an intermediate. When the corresponding gene Ss-XDH was overexpressed in the erythritol-producing Yarrowia lipolytica strain CGMCC7326, threitol was produced with a titer of 112 g·L−1 and yield of 0.37 from glucose. Unexpectedly, gene encoding mannitol dehydrogenase was upregulated in the threitol producing stain, leading to mannitol accumulation in the culture broth. In order to eliminate this byproduct and coproduced erythritol, a second process step based on the culture of Candida parapsilosis was developed to facilitate subsequent threitol purification. This is the first report to efficiently biosynthesize threitol from glucose through the fermentation process by an engineered Y. lipolytica and wild-type Candida parapsilosis.