Effect of β-glycosidase supplementation on vinasse saccharification and L-lactic acid fermentation

Abstract

Efficient pretreatment and enzymatic hydrolysis is critical to achieve effective utilization of lignocellulosic biomass. In this study, the cellulase composition for lignocellulosic biomass hydrolysis was strategically optimized to improve the efficiency of vinasse saccharification and thus enhance L-lactic acid production. The results showed that the supplementation of β-glycosidase (BG) increased sugar production, and the glucose concentration exceeded cellobiose concentration after 48 h of hydrolysis. These results suggested that the addition of BG aided the hydrolysis of cellobiose and reduced the inhibitory effects caused by sugar accumulation. After 72 h to 96 h of hydrolysis, the BG supplementation improved cellobiose and glucose production by 25.7% and 27.4%, respectively. The effect of BG supplementation on L-lactic acid production during the fermentation of microwave-alkali pretreated vinasse was also investigated. Here, the L-lactic acid production from simultaneous saccharification and fermentation (SSF) with the addition of BG was 20.8% higher than that without BG addition, and was also 37.0% higher than production from separate hydrolysis and fermentation with BG addition. These results indicated the utilization efficiency of lignocellulosic biomass for L-lactic acid production could be enhanced by supplementation of BG in SSF.