Improved bioethanol production from corn stover using microwave-assisted protic ionic liquid pretreatment and an engineered S. cerevisiae strain

Construction of a green, economical, and energy-efficient lignocellulose pretreatment process is the core to improve the economic feasibility of the second-generation bioethanol production. This study presents an effective strategy for bioethanol production based on microwave-assisted Diisopropylammonium hydrosulfate ([DIP][HSO₄]) pretreatment. The mechanisms for the depolymerization of the lignocellulose matrix in the novel pretreatment process were proposed by characterize the fractionated pulp and lignin. In this process, the effect of microwave power on mono-sugars production was also investigated. Results indicated that substantial removal of hemicellulose and lignin by 63.75 wt% and 59.36 wt %, respectively, were realized at 170 W for 3 min, which afforded to 69.69 % and 73.78 % of glucan and xylan recoveries in subsequent saccharification. Ethanol fermentation performances of the enzymatic hydrolysate of the pretreated pulps were evaluated using a C5/C6 co-assimilation Saccharomyces cerevisiae YL23. 34.35 g L⁻¹ of ethanol with a yield of 0.42 g g⁻¹ (total monomer sugars in hydrolysate) was received in the end fermentation broth using the fed-batch hydrolysate containing total 80.88 g L⁻¹ of mono-sugars. Correspondingly, 12.01 g of bioethanol and 13.12 g of technical lignin were co-generated from 100 g of dried corn stover.