AUTHOR=Zhang Jia , Xu Teng , Wang Xiaohang , Jing Xiaoyan , Zhang Jia , Hong Jiong , Xu Jian , Wang Jichao 

TITLE=Lignocellulosic xylitol production from corncob using engineered Kluyveromycesmarxianus

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2022.1029203

DOI=10.3389/fbioe.2022.1029203

ISSN=2296-4185

ABSTRACT=<p>Xylitol production from lignocellulose hydrolysate is a sustainable and environment-friendly process. In this study, a systematic process of converting corncob waste into xylitol is described. First, the corncobs are hydrolyzed with acid to a hydrolysate. Second, <italic>Kluyveromyces marxianus</italic> YZJQ016 derived from <italic>K. marxianus</italic> YZJ074, constructed by overexpressing <italic>ScGAL2-N376F</italic> from <italic>Saccharomyces cerevisiae</italic>, <italic>CtXYL1</italic> from <italic>Candida tropicalis</italic>, and <italic>KmZWF1</italic> from <italic>K. marxianus</italic>, produces xylitol from the hydrolysate. A total of ten xylose reductase genes were evaluated, and <italic>CtXYL1</italic> proved best by showing the highest catalytic activity under the control of the <italic>KmGAPDH</italic> promoter. A 5 L fermenter at 42°C produced 105.22 g/L xylitol using <italic>K. marxianus</italic> YZJQ016—the highest production reported to date from corncob hydrolysate. Finally, for crystallization of the xylitol, the best conditions were 50% (v/v) methanol as an antisolvent, at 25°C, with purity and yield of 99%–100% and 74%, respectively—the highest yield reported to date.</p>