Temperature profiled simultaneous saccharification and co-fermentation of corn stover increases ethanol production at high solid loading

Trade-off temperature used in traditional SScF process always resulted in inhibition on enzymatic hydrolysis (low temperature inhibition, LTI). Thus, effect of temperature and solid loading on LTI was investigated in this study. Results showed that LTI was more severe at lower temperature and higher solid loading. Accordingly, a novel temperature profiled SScF process was designed. Two specific yeast strains, high temperature resistant Saccharomyces cerevisiae and xylose utilizing S. cerevisiae were co-cultured in the novel SScF process. Through eliminating sugars accumulation and alleviating ethanol repression by process optimization, 59.8 g/L ethanol was achieved in temperature profiled SScF at 12% glucan loading. Cell viability of yeast in co-culture SScF was ten times, sometimes even thousands of times, of that in mono-culture SScF during the late phase of the fermentation (48-108 h). It suggested that high temperature resistant strain helped the xylose utilizing strain maintain cell viability in SScF at high temperature (42 degrees C). Based on the results, the designed novel temperature profiled SScF process showed appealing potential for bioethanol production at high solid loading and high temperature.