An accessory enzymatic system of cellulase for simultaneous saccharification and co-fermentation
Han Liu, Xuxin Wang, Yan Liu, Zhuoran Kang, Jiaqi Lu, Yutong Ye, Zhipeng Wang, Xinshu Zhuang, Shen Tian
Abstract
The enhanced hydrolysis of xylan-type hemicellulose is important to maximize ethanol production yield and substrate utilization rate in lignocellulose-based simultaneous saccharification and co-fermentation system. In this study, we conduct δ-integration CRISPR Cas9 to achieve multicopy chromosomal integration with high efficiency of reductase–xylitol dehydrogenase pathway in Saccharomyces cerevisiae. Subsequently, we devise a consolidated bioprocessing-enabling S. cerevisiae consortium, in which every engineered yeast strain could secrete or display different assembly components to be adaptively assembled on the surface of scaffoldin-displaying yeast cell for synergistic catalysis and co-fermentation from steam-exploded Pennisetum purpureum. Despite the accumulation of xylitol, the maximum ethanol titer of the genetically engineered yeast strain reached 12.88 g/l with the cellulose conversion of 91.21% and hemicellulose conversion of 55.25% under 30 ºC after 96 h with the addition of commercial cellulase. The elaborated cellulosomal organization toward genetic engineering of an industrially important microorganism presents a designed approach for advanced lignocellulolytic potential and improved capability of biofuel processing.