Construction of fast xylose-fermenting yeast based on industrial ethanol-producing diploid Saccharomyces cerevisiae by rational design and adaptive evolution
1 CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China
2 Shanghai Research and Development Center of Industrial Biotechnology, 528 Ruiqing Road, Shanghai 201201, China
BMC Biotechnology 2013, 13:110 doi:10.1186/1472-6750-13-110Published: 19 December 2013
It remains a challenge for recombinant S. cerevisiae to convert xylose in lignocellulosic biomass hydrolysates to ethanol. Although industrial diploid strains are more robust compared to laboratory haploid strains, however, industrial diploid S. cerevisiae strains have been less pursued in previous studies. This work aims to construct fast xylose-fermenting yeast using an industrial ethanol-producing diploid S. cerevisiae strain as a host.
Fast xylose-fermenting yeast was constructed by genome integration of xylose-utilizing genes and adaptive evolution, including 1) Piromyces XYLA was introduced to enable the host strain to convert xylose to xylulose; 2) endogenous genes (XKS1, RKI1, RPE1, TKL1, and TAL1) were overexpressed to accelerate conversion of xylulose to ethanol; 3) Candida intermedia GXF1, which encodes a xylose transporter, was introduced at the GRE3 locus to improve xylose uptake; 4) aerobic evolution in rich xylose media was carried out to increase growth and xylose consumption rates. The best evolved strain CIBTS0735 consumed 80 g/l glucose and 40 g/l xylose in rich media within 24 hours at an initial OD600 of 1.0 (0.63 g DCW/l) and produced 53 g/l ethanol.
Based on the above fermentation performance, we conclude that CIBTS0735 shows great potential for ethanol production from lignocellulosic biomass.