AUTHOR=Zha Jian , Hu Menglong , Shen Minghua , Li Bingzhi , Wang Jingyu , Yuan Yingjin 

TITLE=Balance of XYL1 and XYL2 expression in different yeast chassis for improved xylose fermentation

JOURNAL=Frontiers in Microbiology

VOLUME=3

YEAR=2012

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2012.00355

DOI=10.3389/fmicb.2012.00355

ISSN=1664-302X

ABSTRACT=<p>Reducing xylitol formation is necessary in engineering xylose utilization in recombinant <italic>Saccharomyces cerevisiae</italic> for ethanol production through xylose reductase/xylitol dehydrogenase pathway. To balance the expression of <italic>XYL1</italic> and mutant <italic>XYL2</italic> encoding xylose reductase (XR) and NADP<sup>+</sup>-dependent xylitol dehydrogenase (XDH), respectively, we utilized a strategy combining chassis selection and direct fine-tuning of <italic>XYL1</italic> and <italic>XYL2</italic> expression in this study. A <italic>XYL1</italic> gene under the control of various promoters of <italic>ADH1</italic>, truncated <italic>ADH1</italic> and <italic>PGK1</italic>, and a mutated <italic>XYL2</italic> with different copy numbers were constructed into different xylose-utilizing modules, which were then expressed in two yeast chassises W303a and L2612. The strategy enabled an improved L2612-derived recombinant strain with <italic>XYL1</italic> controlled by promoter <italic>PGK1</italic> and with two copies of <italic>XYL2</italic>. The strain exhibited a 21.3% lower xylitol yield and a 40.0% higher ethanol yield. The results demonstrate the feasibility of the combinatorial strategy for construction of an efficient xylose-fermenting <italic>S. cerevisiae</italic>.</p>