Understanding the Dynamics of the Saccharomyces cerevisiae and Scheffersomyces stipitis Abundance in Co-culturing Process for Bioethanol Production from Corn Stover

The co-utilization pentose and hexose in lignocellulosic biomass hydrolysate is the core for economically fermentative production of the second-generation bioethanol as sustainable biofuel candidate. In this study, S. cerevisiae was co-cultured with S. stipitis for highly effective bioethanol production from pentose and hexose enriched lignocellulose hydrolysate. Results indicated that the co-culturing process could be divided into two phases (a twin-consortium phase and a second phase with xylose conversion by S. stipitis). Under the optimized condition (S. cerevisiae/S. stipitis inoculum ratio of 20/80 (v/v), overall inoculation size of 10% (v/v), and ventilation volume of 0.01 vvm), the highest ethanol yield of 0.39 g/g (of monomer sugars) can be achieved. Dynamics of the S. stipitis and S. cerevisiae abundance were further investigated, which revealed that the flora of S. cerevisiae contains a large part in the twin-consortium phase, while the S. stipitis flora gradually increased with the lengthen of fermentation period, and finally became the predominated strain after used up the glucose consumption in corn stover hydrolysate. [GRAPHICS] .