Knock Down of Erythrulose Kinase (eyk1) Leads to the Enhancement of Erythritol Production in Yarrowia lipolytica Mutant Strain YE4-2

Erythritol is a nearly zero-calorie sweetener, which is in great demand in food and health care industry. Our previous work obtained a Yarrowia lipolytica mutant strain YE4-2 with high erythritol yield. However, its conversion rate of glucose needs further improvement. Erythrulose kinase (eyk1) participates in the early stages of erythritol catabolism; the existence of eyk1 prevents the accumulation of erythritol. In this study, the genetic transformation system of Y. lipolytica YE4-2 was firstly established and the Cre/loxp homologous recombination knockout system was constructed. By using the Cre/loxp system, eyk1 gene was deleted. According to the PCR verification of eyk1 gene, it was preliminarily determined that one allele of eyk1 in this recombinant strain was knocked out. The recombination strain showed an average conversion rate of 48.51%, which was 49.26% higher than that of YE4-2 and the erythritol productivity is increased by 62.26%, which would be a significant improvement in the industrial scale.