TY - JOUR T1 - Comparative study on a series of recombinant flocculent Saccharomyces cerevisiae strains with different expression levels of xylose reductase and xylulokinase. AU - Matsushika,Akinori, AU - Sawayama,Shigeki, Y1 - 2011/03/02/ PY - 2010/10/30/received PY - 2011/01/30/revised PY - 2011/02/02/accepted PY - 2011/11/25/entrez PY - 2011/11/25/pubmed PY - 2012/4/13/medline SP - 466 EP - 71 JF - Enzyme and microbial technology JO - Enzyme Microb Technol VL - 48 IS - 6-7 N2 - Ethanol production from xylose is important for the utilization of lignocellulosic biomass as raw materials. Recently, we reported the development of an industrial xylose-fermenting Saccharomyces cerevisiae strain, MA-R4, which was engineered by chromosomal integration to express the genes encoding xylose reductase and xylitol dehydrogenase from Pichia stipitis along with S. cerevisiae xylulokinase gene constitutively using the alcohol-fermenting flocculent yeast strain, IR-2. IR-2 has the highest xylulose-fermenting ability of the industrial diploid strains, making it a useful host strain for genetically engineering xylose-utilizing S. cerevisiae. To optimize the activities of xylose metabolizing enzymes in the metabolic engineering of IR-2 for further improvement of ethanol production from xylose, we constructed a set of recombinant isogenic strains harboring different combinations of genetic modifications present in MA-R4, and investigated the effect of constitutive expression of xylulokinase and of different levels of xylulokinase and xylose reductase activity on xylose fermentation. This strain comparison showed that constitutive expression of xylulokinase increased ethanol production from xylose at the expense of xylitol excretion, and that high activity of xylose reductase resulted in an increased rate of xylose consumption and an increased glycerol yield. Moreover, strain MA-R6, which has moderate xylulokinase activity, grew slightly better but accumulated more xylitol than strain MA-R4. These results suggest that fine-tuning of introduced enzyme activity in S. cerevisiae is important for improving xylose fermentation to ethanol. SN - 1879-0909 UR - https://www.unboundmedicine.com/medline/citation/22113018/Comparative_study_on_a_series_of_recombinant_flocculent_Saccharomyces_cerevisiae_strains_with_different_expression_levels_of_xylose_reductase_and_xylulokinase_ DB - PRIME DP - Unbound Medicine ER -