Deficiency of β-Glucosidase Beneficial for the Simultaneous Saccharification and Lipid Production by the Oleaginous Yeast Lipomyces starkeyi.

It is inevitably for cellobiose to be co-generated during enzymatic hydrolysis of cellulose, especially when the cellulase is lack of β-glucosidase activity. In the present study, cellobiose was found superior to glucose for cell growth by L. starkeyi, regardless of the sugar concentrations. Glucose was assimilated preferentially when cellobiose and glucose were co-fermented. Deficiency of β-glucosidase was observed to be beneficial for the simultaneous saccharification and lipid production (SSLP). High lipid titer and cellulose conversion of 9.1 g/L and 92.4%, respectively, were achieved when cellulase with low β-glucosidase activity was supplemented. The SSLP achieved higher lipid titer of 9.5 g/L when a pre-hydrolysis process was introduced. The glucosidase generated by L. starkeyi was primarily cell-bound, which contributed significantly to the cellobiose utilization and the high lipid production. These results provided a novel scheme for enhanced lipid production from lignocellulosic biomass with reduced enzyme usage, which is believed to facilitate the design of a more cost-effective lignocellulose-to-lipid route.