Microbial lipid production from enzymatic hydrolysate of corn stover pretreated by combining with biological pretreatment and alkalic salt soaking

Abstract

The conversion of lignocellulose for biofuel production requires an effective pretreatment to disrupt the recalcitrant plant cell walls and to make the cellulose accessible to cellulases. In this study, sequential biological pretreatment (BP) with Galactomyces sp. CCZU11-1 under the mild condition and alkalic salt pretreatment (AP) with Na2CO3 by autoclaving was used to pretreat untreated corn stover (CS) for enhancing its enzymatic saccharification. After the optimization, the optimum pretreatment conditions were obtained. The crystallinity, porosity, and morphology of the pretreated solid residue of CS were correlated with the enhancement of enzymatic saccharification. After 72 h, the yields of glucose from the hydrolysis of 50 g/L BP-AP-CS with a cocktail of Galactomyces sp. CCZU11-1 cellulases in the absence and presence of Na2CO3 (0.82 wt%) could be obtained at 47.2% and 46.1% respectively. Using BP-AP-CS-hydrolysates containing 25.6 g/L glucose as carbon source, microbial lipids effectively produced by Rhodococcus pyridinivorans CCZU-B16 in the presence of Na2CO3 (0.82 wt%). Four fatty acids including palmitic acid (C16:0; 23.5%), palmitoleic acid (C16:1; 19.0%), stearic acid (C18:0; 16.2%), and oleic acid (C18:1; 24.8%) were distributed in total fatty acids. In conclusion, this combination pretreatment strategy has potential application for the production of microbial lipids from biomass in future.