title: Microaerobic conversion of xylose to ethanol in recombinant Saccharomyces cerevisiae SX6(MUT) expressing cofactor-balanced xylose metabolic enzymes and deficient in ALD6.
abstract: Xylose is a major monosugar in cellulosic biomass and should be utilized for cost-effective ethanol production. In this study, xylose-converting ability of recombinant Saccharomyces cerevisiae SX6(MUT) expressing NADH-preferring xylose reductase mutant (R276H) and other xylose-metabolic enzymes, and deficient in aldehyde dehydrogenase 6 (Ald6p) were characterized at microaerobic conditions using various sugar mixtures. The reduction of air supply from 0.5vvm to 0.1vvm increased specific ethanol production rate by 75% and did not affect specific xylose consumption rate. In batch fermentations using various concentrations of xylose (50-104g/L), higher xylose concentration enhanced xylose consumption rate and ethanol productivity but reduced ethanol yield, owing to the accumulation of xylitol and glycerol from xylose. SX6(MUT) consumed monosugars in pitch pine hydrolysates and produced 23.1g/L ethanol from 58.7g/L sugars with 0.39g/g ethanol yield, which was 14% higher than the host strain of S. cerevisiae D452-2 without the xylose assimilating enzymes. In conclusion, S. cerevisiae SX6(MUT) was characterized to possess high xylose-consuming ability in microaerobic conditions and a potential for ethanol production from cellulosic biomass.
authors.affiliation: Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 136-702, Republic of Korea.
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Jo
authors.affiliation: Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 136-702, Republic of Korea.
authors.forename: Yeong-Je
authors.initials: YJ
authors.lastname: Seong
authors.affiliation: Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 136-702, Republic of Korea.
authors.forename: Hyun-Soo
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Division of Wood Chemistry and Microbiology, Korea Forest Research Institute, Seoul 130-172, Republic of Korea.
authors.forename: Soo Min
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 136-702, Republic of Korea; Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Soo-Jung
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Bio and Chemical Engineering, Hongik University, Sejong 339-701, Republic of Korea.
authors.forename: Kyungmoon
authors.initials: K
authors.lastname: Park
authors.affiliation: Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 136-702, Republic of Korea. Electronic address: ycpark@kookmin.ac.kr.
authors.forename: Yong-Cheol
authors.initials: YC
authors.lastname: Park
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000332:Aerobiosis; D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D061249:Batch Cell Culture Techniques; D050260:Carbohydrate Metabolism / Q000187:drug effects; D003067:Coenzymes / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D028223:Pinus / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism*
chemical_list: D000085:Acetates; D003067:Coenzymes; D011994:Recombinant Proteins; D000431:Ethanol; D014994:Xylose; D000445:Aldehyde Oxidoreductases; C018699:aldehyde dehydrogenase (NAD(P)+)
keywords: ALD6; Ethanol; NADH-preferring xylose reductase; Pitch pine hydrolysates; Saccharomyces cerevisiae; Xylose