Xiaoming Bao
Shandong University, China
Title: Engineering on wild type diploid Saccharomyces cerevisiae for second-generation bioethanol production
Biography
Biography: Xiaoming Bao
Abstract
The cost-effective and sustainable production of second-generation bioethanol, which made from lignocellulosic materials, must resolve two problems: cofermenting xylose with glucose and enhancing strain tolerance to lignocellulosic inhibitors. In our recent work, a robust diploid Saccharomyces cerevisiae strain BSIF was used as chassis cell. The novel Ru-xylA gene (US 8586336 B2) that expressed high xylose isomerase activity in S. cerevisiae and the MGT05196(N360F) gene (CN 104263739A) encoding a transporter that specifically transported xylose without any glucose-inhibition, were introduced into strain BSIF, as well as overexpressed endogenous XKS1 and genes of pentose phosphate pathway, etc. These rationally designed genetic modifications combined with alternant evolution in xylose and leach liquor of pretreated corn stover (PCS) endowed excellent xylose fermentation and inhibitor resistant capacity to the final resulting strain LF1 (CN 105199976A). The ethanol yield and specific xylose consumption rate of LF1 were 0.447 g g-1 and 1.073 g g-1 h-1 in fermentation of 40 g L-1 xylose, and were 0.474 g g-1 and 1.751 g g-1 h-1 in fermentation with mixed sugar (80 g L-1 glucose and 40 g L-1 xylose). In the fermentation of PCS hydrolysate, LF1 consumed 77 g L-1 glucose and 36 g L-1 xylose in 40 h with an ethanol yield of 0.411 g g-1, highlighting its potential use in second-generation bioethanol production. More genetic and evolutionary measures are being taken to make strain LF1 more suitable to producing second-generation bioethanol from various lignocellulosic hydrolysates.