title: Two-stage transcriptional reprogramming in Saccharomyces cerevisiae for optimizing ethanol production from xylose.
abstract: Conversion of lignocellulosic material to ethanol is a major challenge in second generation bio-fuel production by yeast Saccharomyces cerevisiae. This report describes a novel strategy named "two-stage transcriptional reprogramming (TSTR)" in which key gene expression at both glucose and xylose fermentation phases is optimized in engineered S. cerevisiae. Through a combined genome-wide screening of stage-specific promoters and the balancing of the metabolic flux, ethanol yields and productivity from mixed sugars were significantly improved. In a medium containing 50g/L glucose and 50g/L xylose, the top-performing strain WXY12 rapidly consumed glucose within 12h and within 84h it consistently achieved an ethanol yield of 0.48g/g total sugar, which was 94% of the theoretical yield. WXY12 utilizes a KGD1 inducible promoter to drive xylose metabolism, resulting in much higher ethanol yield than a reference strain using a strong constitutive PGK1 promoter. These promising results validate the TSTR strategy by synthetically regulating the xylose assimilation pathway towards efficient xylose fermentation.
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China; Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada. Electronic address: caolimin@cnu.edu.cn.
authors.forename: Limin
authors.initials: L
authors.lastname: Cao
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China.
authors.forename: Xingliang
authors.initials: X
authors.lastname: Tang
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China.
authors.forename: Xinyuan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China.
authors.forename: Jingtao
authors.initials: J
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China.
authors.forename: Xuelei
authors.initials: X
authors.lastname: Tian
authors.affiliation: Department of Biochemical Engineering, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, China.
authors.forename: Jingyu
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minneapolis, MN, USA.
authors.forename: Mingyong
authors.initials: M
authors.lastname: Xiong
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China; Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada. Electronic address: weixiao@cnu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Xiao
mesh_terms: D000431:Ethanol / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D060847:Metabolic Engineering; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*; D014994:Xylose / Q000378:metabolism*
chemical_list: D000431:Ethanol; D014994:Xylose
keywords: Ethanol; Saccharomyces cerevisiae; Two-stage transcription reprogramming; Xylose; Xylose reductase