Effects of NADH-preferring xylose reductase expression on ethanol production from xylose in xylose-metabolizing recombinant Saccharomyces cerevisiae

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• 作者：Sung-Haeng Lee^a ; Tsutomu Kodaki^b ; Yong-Cheol Park^c ; ^{ycpark@kookmin.ac.kr} ; Jin-Ho Seo^a ; ^d ; ^{jhseo94@snu.ac.kr}
• 关键词：Ethanol ; Xylose ; Saccharomyces cerevisiae ; NADH-preferable xylose reductase
• 刊名：Journal of Biotechnology
• 出版年：2012
• 期刊代码：53_01681656
• 类别：imm
• 出版时间：30 April, 2012
• 卷：158
• 期：4
• 页码：184-191
• 文件大小：412 K

摘要

Efficient conversion of xylose to ethanol is an essential factor for commercialization of lignocellulosic ethanol. To minimize production of xylitol, a major by-product in xylose metabolism and concomitantly improve ethanol production, Saccharomyces cerevisiae D452-2 was engineered to overexpress NADH-preferable xylose reductase mutant (XR^MUT) and NAD⁺-dependent xylitol dehydrogenase (XDH) from Pichia stipitis and endogenous xylulokinase (XK). In vitro enzyme assay confirmed the functional expression of XR^MUT, XDH and XK in recombinant S. cerevisiae strains. The change of wild type XR to XR^MUT along with XK overexpression led to reduction of xylitol accumulation in microaerobic culture. More modulation of the xylose metabolism including overexpression of XR^MUT and transaldolase, and disruption of the chromosomal ALD6 gene encoding aldehyde dehydrogenase (SX6^MUT) improved the performance of ethanol production from xylose remarkably. Finally, oxygen-limited fermentation of S. cerevisiae SX6^MUT resulted in 0.64 g l^鈭? h^鈭? xylose consumption rate, 0.25 g l^鈭? h^鈭? ethanol productivity and 39%ethanol yield based on the xylose consumed, which were 1.8, 4.2 and 2.2 times higher than the corresponding values of recombinant S. cerevisiae expressing XR^MUT, XDH and XK only.