title: Improvement of xylose fermentation in respiratory-deficient xylose-fermenting Saccharomyces cerevisiae.
abstract: Effective conversion of xylose in lignocelluloses is expected to reduce the production cost of second-generation biofuels significantly. The factors affecting xylose fermentation in Saccharomyces cerevisiae that express xylose reductase-xylitol dehydrogenase (XR-XDH) are studied. Although overproduction of non-oxidative pentose phosphate pathway significantly increased the aerobic-specific growth rate on xylose and slightly improved conversion of xylose to ethanol under oxygen-limited conditions, the elimination of respiration by deleting cytochrome C oxidase subunit IV gene impeded aerobic growth on xylose. However, the adaptive evolution of the respiratory-deficient strain with an NADP(+)-preferring XDH mutant in xylose media dramatically improved its xylose-fermenting ability. The specific growth rate, ethanol yield, and xylitol yield of the evolved strain on xylose were 0.06h(-1), 0.39gg(-1), and 0.13gg(-1) consumed xylose, respectively. Similar to anaerobic fermentation, the evolved strain exhibited accumulated ethanol rather than recycled it under aerobic conditions.
authors.affiliation: The State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, China.
authors.forename: Bingyin
authors.initials: B
authors.lastname: Peng
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Li
authors.forename: Xiao
authors.initials: X
authors.lastname: Chen
authors.forename: Jin
authors.initials: J
authors.lastname: Hou
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Bao
mesh_terms: D000449:Aldehyde Reductase / Q000235:genetics / Q000378:metabolism; D000693:Anaerobiosis / Q000187:drug effects / Q000235:genetics; D050542:D-Xylulose Reductase / Q000235:genetics / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects / Q000235:genetics*; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014994:Xylose / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D014994:Xylose; D000449:Aldehyde Reductase; D050542:D-Xylulose Reductase; D003576:Electron Transport Complex IV