title: Alteration of xylose reductase coenzyme preference to improve ethanol production by Saccharomyces cerevisiae from high xylose concentrations.
abstract: A K270R mutation of xylose reductase (XR) was constructed by site-direct mutagenesis. Fermentation results of the F106X and F106KR strains, which carried wild type XR and K270R respectively, were compared using different substrate concentrations (from 55 to 220 g/L). After 72 h, F106X produced less ethanol than xylitol, while F106KR produced ethanol at a constant yield of 0.36 g/g for all xylose concentrations. The xylose consumption rate and ethanol productivity increased with increasing xylose concentrations in F106KR strain. In particular, F106KR produced 77.6g/L ethanol from 220 g/L xylose and converted 100 g/L glucose and 100g/L xylose into 89.0 g/L ethanol in 72h, but the corresponding values of F106X strain are 7.5 and 65.8 g/L. The ethanol yield of F106KR from glucose and xylose was 0.42 g/g, which was 82.3% of the theoretical yield. These results suggest that the F106KR strain is an excellent producer of ethanol from xylose.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China.
authors.forename: Mingyong
authors.initials: M
authors.lastname: Xiong
authors.forename: Guohua
authors.initials: G
authors.lastname: Chen
authors.forename: John
authors.initials: J
authors.lastname: Barford
mesh_terms: D000449:Aldehyde Reductase / Q000235:genetics / Q000378:metabolism*; D000693:Anaerobiosis; D056804:Biofuels; D003067:Coenzymes / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense / Q000235:genetics; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D013045:Species Specificity; D014994:Xylose / Q000378:metabolism*; D014996:Xylulose / Q000378:metabolism*
chemical_list: D056804:Biofuels; D003067:Coenzymes; D017931:DNA Primers; D000431:Ethanol; D014996:Xylulose; D014994:Xylose; D000449:Aldehyde Reductase