title: A new source of resistance to 2-furaldehyde from Scheffersomyces (Pichia) stipitis for sustainable lignocellulose-to-biofuel conversion.
abstract: Aldehyde inhibitory compounds derived from lignocellulosic biomass pretreatment have been identified as a major class of toxic chemicals that interfere with microbial growth and subsequent fermentation for advanced biofuel production. Development of robust next-generation biocatalyst is a key for a low-cost biofuel production industry. Scheffersomyces (Pichia) stipitis is a naturally occurring C-5 sugar utilization yeast; however, little is known about the genetic background underlying its potential tolerance to biomass conversion inhibitors. We investigated and identified five uncharacterized putative aryl-alcohol dehydrogenase genes (SsAADs) from this yeast as a new source of resistance against biomass fermentation inhibitor 2-furaldehyde (furfural) by gene expression, gene cloning, and direct enzyme assay analysis using partially purified proteins. All five proteins from S. stipitis showed furfural reduction using cofactor NADH. An optimum active temperature was observed at 40 °C for SsAad1p; 30 °C for SsAad3p, SsAad4p, and SsAad5p; and 20 °C for SsAad2p. SsAad2p, SsAad3p, and SsAad4p showed tolerance to a wide range of pH from 4.5 to 8, but SsAad1p and SsAad5p were sensitive to pH changes beyond 7. Genes SsAAD2, SsAAD3, and SsAAD4 displayed significantly enhanced higher levels of expression in response to the challenge of furfural. Their encoding proteins also showed higher levels of specific activity toward furfural and were suggested as core functional enzymes contributing aldehyde resistance in S. stipitis.
authors.affiliation: Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, China.|BioEnergy Research Unit, USDA-ARS, National Center for Agricultural Utilization Research, 1815 N University St., Peoria, IL, 61604, USA.|Department of Microbiology, College of Life Sciences, Henan Agricultural University, Zhengzhou, Henan, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.affiliation: BioEnergy Research Unit, USDA-ARS, National Center for Agricultural Utilization Research, 1815 N University St., Peoria, IL, 61604, USA. ZLewis.Liu@ars.usda.gov.
authors.forename: Z
authors.initials: Z
authors.lastname: Lewis Liu
authors.affiliation: Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, China.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, China. mgen@sicau.edu.cn.|Institute of Natural Resources and Geographic Information Technology, College of Resources, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, China. mgen@sicau.edu.cn.
authors.forename: Menggen
authors.initials: M
authors.lastname: Ma
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000447:Aldehydes / Q000378:metabolism; D055162:Biocatalysis; D056804:Biofuels / Q000191:economics*; D018533:Biomass; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005662:Furaldehyde / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008031:Lignin / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010843:Pichia / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000447:Aldehydes; D056804:Biofuels; D009243:NAD; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin; D005662:Furaldehyde; D000429:Alcohol Oxidoreductases; C055882:aryl-alcohol dehydrogenase
keywords: Aldehyde reduction; Biofuel conversion; Detoxification; Tolerant strain development; Yeast