High-temperature Fermentation of Corn Stover for Biodiesel Production Using Candida Tropicalis with Enhanced Lipid Accumulation: A New Strategy for Breeding Thermotolerant Biodiesel-Production Strains

Efficient biodiesel production from biomass is essential for the green-oriented energy transition. The current incongruity between fermentation temperature and microbial thermotolerance is one of the key factors restricting biodiesel production, and it is difficult to solve this problem relying only on conventional microbial characterization and breeding methods. We propose a strategy to solve the corn stover cellulose utilization problem by developing thermotolerant biodiesel-production yeast strains. Candida tropicalis was initially improved by adaptive laboratory evolution and then mutated by atmospheric and room-temperature plasma mutagenesis to obtain a thermotolerant strain capable of growing at temperatures up to 45 °C. Two rounds of fluorescence-activated cell sorting were used to select high lipid content cells, which resulted in a 16.8% increase in lipid accumulation capacity compared to the original cells. The simultaneous saccharification fermentation of the generated strain with pretreated corn stover at 44 °C yielded a lipid generation efficiency of 86.2 ± 2 mg/g. This study provides a new method and an alternative strain for the selection and breeding of high-thermotolerance and high biodiesel-production yeasts and offers a feasible strategy for lignocellulosic fermentation for biodiesel production at elevated temperatures using the new industrial strain.