Construction of a xylose-metabolizing yeast by genome integration of xylose isomerase gene and investigation of the effect of xylitol on fermentation |
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Authors: | Takanori Tanino Atsushi Hotta Tomonori Ito Jun Ishii Ryosuke Yamada Tomohisa Hasunuma Chiaki Ogino Naoto Ohmura Takayuki Ohshima Akihiko Kondo |
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Institution: | (1) Department of Chemical and Environmental Engineering, Graduate School of Engineering, Gunma University, 1-5-1 Tenjincho, Kiryu Gunma, 376-8515, Japan;(2) Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan;(3) Organization of Advanced Science and technology, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan |
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Abstract: | A yeast with the xylose isomerase (XI) pathway was constructed by the multicopy integration of XI overexpression cassettes
into the genome of the Saccharomyces cerevisiae MT8-1 strain. The resulting yeast strain successfully produced ethanol from both xylose as the sole carbon source and a mixed
sugar, consisting of xylose and glucose, without any adaptation procedure. Ethanol yields in the fermentation from xylose
and mixed sugar were 61.9% and 62.2% of the theoretical carbon recovery, respectively. Knockout of GRE3, a gene encoding nonspecific aldose reductase, of the host yeast strain improved the fermentation profile. Not only specific
ethanol production rates but also xylose consumption rates was improved more than twice that of xylose-metabolizing yeast
with the XI pathway using GRE3 active yeast as the host strain. In addition, it was demonstrated that xylitol in the medium exhibits a concentration-dependent
inhibition effect on the ethanol production from xylose with the yeast harboring the XI-based xylose metabolic pathway. From
our findings, the combination of XI-pathway integration and GRE3 knockout could be result in a consolidated xylose assimilation pathway and increased ethanol productivity. |
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