Efficient utilization of hemicellulose and cellulose in alkali liquor-pretreated corncob for bioethanol production at high solid loading by Spathaspora passalidarum U1-58

- The U1-58 mutant producing ethanol from xylose at high efficiency was obtained.
- The cellulose and hemicellulose in corncob could be efficiently utilized.
- The highest ethanol titer and yield were 53.24 g/L and 75.35%, respectively.

The bioethanol fermentation of pretreated corncob was investigated using Spathaspora passalidarum U1-58, which simultaneously utilizes glucose and xylose for high-efficiency ethanol production. Two approaches, namely, separate hydrolysis and co-fermentation (SHCF) and simultaneous saccharification and co-fermentation (SSCF), were optimized to test the ethanol fermentation potential of U1-58. The highest ethanol titer of 42.46 g/L and yield of 72.12% were acquired in SHCF, whereas 53.24 g/L ethanol and yield of 75.35% were obtained in SSCF at solid-to-liquid ratio of 1:5 (w/v). Approximately 86.20% of cellulose and 82.99% of hemicellulose were consumed in SSCF after 96 h, and at least 10.49 g/L ethanol was produced from hemicellulose, which corresponded to 37.59% of the theoretical yield. Compared with the published cellulosic ethanol fermentation cases, the present work presented high ethanol titer and yield, and cellulose and hemicellulose could be efficiently utilized for ethanol production.