Screening of Foamless Yarrowia lipolytica Strain and Metabolic Engineering for Erythritol Production from Sucrose-Based Feedstocks

The industrial fermentation process is often accompanied by foam production, which can reduce the available volume of the bioreactor and increase the risk of bacterial contamination. The current investigation employed a combination of a non-homologous end joining-mediated integration mutation and a spontaneous mutation of Yarrowia lipolytica to screen for the foamless strain capable of producing erythritol. Genome resequencing analysis suggests that genes YALI0_A01892g and YALI0_F06006g associated with yeast flocculation play a significant role in the development of the foamless variant of Y. lipolytica. Subsequently, Saccharomyces cerevisiae invertase was displayed on the cell surface by fusing the cell wall protein YlPir1. The yield, production, and productivity of erythritol reached 0.57 g/g sucrose, 195 g/L, and 1.88 g/(L h), respectively, using sugar cane syrup as a carbon source in a 5 L bioreactor, which is one of the highest yields of erythritol obtained from sucrose-based feedstocks. The defoamer addition was 1.63 mL, which is less than half of the control during the fermentation process by the engineered strain YlxsFL02. The approach described here provides a roadmap for future research into the genetic basis of foamless fermentation in Y. lipolytica, which could lead to further reductions in the cost of erythritol production.