Synergistic effect of transporter and pathway engineering on the key performance indicators of erythritol synthesis by the yeast Yarrowia lipolytica.

Abstract

Erythritol, a food additive, is produced on an industrial scale using the yeast Yarrowia lipolytica. Nevertheless, the key performance indicators (KPIs) have been found to be unsatisfactory, resulting in elevated erythritol production cost. This study demonstrated that the KPIs (titer, productivity, and yield) of erythritol can be improved by the synergistic application of transporter and pathway engineering strategies in the producing strain. The engineered Y. lipolytica strain Ylxs48 exhibits a glucose consumption rate of 310 g/L of glucose within 46 h during batch culture in 3, 100, and 200 L bioreactors as compared to above 72 h for the parental strain Ylxs01. The erythritol yield achieved ranges from 0.69 to 0.74 g/g depending on the culture conditions as compared to 0.55-0.57 g/g for the parental strain Ylxs01. The productivity surpasses 4.60 g/(L·h), representing a 1.91-fold improvement over the parental strain Ylxs01 in 3, 100, or 200 L bioreactors. Under fed-batch conditions in a 200 L bioreactor, an erythritol titer of 355.81 g/L was achieved, marking the highest titer ever reported. This increased erythritol titer enabled crystallization at 4°C directly from the clear supernatant, eliminating the requirement for evaporation or concentration steps. A comprehensive techno-economic analysis of the entire process conclusively demonstrated that implementing the industrial process based on the engineered strain Ylxs48 led to a significant 23% reduction in production cost. This approach holds the potential to substantially reduce erythritol costs and provides novel insights for engineering other industrial strains.

Importance: The expansion of the erythritol market attracted excessive capital injection, resulting in overcapacity, operational difficulties, and even bankruptcy of erythritol manufacturers. Technology upgrades in the industry are imminent. However, the production technology of existing enterprises is seriously homogenized, and there is a lack of competitive core-producing strains. In this study, the industrial erythritol-producing strain Y. lipolytica CGMCC7326 was genetically modified by integrating substrate transport and pathway modification, which improved the conversion of glucose and significantly improved KPIs, thereby reducing the erythritol production cost.