Development of a Xylose Utilizing Saccharomyces Cerevisiae As a Platform for Lignocellulosic Biofuels/Biochemical Production

Engineering Saccharomyces cerevisiae for efficient pentose fermentation has improved economic feasibility and sustainability of bioethanol production from lignocellulosic biomass. Yet, pentose utilizing strains require further engineering mainly to improve co-fermentation efficiency and diversify products. In this study, we developed an easily engineerable strain of efficient xylose utilizing S. cerevisiae through combinatorial engineering. Specifically, we integrated xylose catabolic pathway genes in gre3 and pho13 loci by using a marker-free genome editing tool of CRISPR/Cas9 system. The rationally engineered strain was then further improved by evolutionary engineering generating efficient xylose fermenting strain of S. cerevisiae(XUSE). Xylose fermentation performance of XUSE was comparable to SXA-R2PE, one of the best xylose utilizing S. cerevisiae. The whole genome sequencing revealed beneficial mutations obtained by evolutionary engineering. Consequently, this study provides a promising platform strain of S. cerevisiae for biofuels/biochemical production from lignocellulosic biomass.