Liu Zhuo, Inokuma Kentaro, Ho Shih-Hsin, den Haan Riaan, van Zyl Willem H, Hasunuma Tomohisa, Kondo Akihiko
Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
Biotechnol Bioeng. 2017 Jun;114(6):1201-1207. doi: 10.1002/bit.26252. Epub 2017 Mar 6.
Crystalline cellulose is one of the major contributors to the recalcitrance of lignocellulose to degradation, necessitating high dosages of cellulase to digest, thereby impeding the economic feasibility of cellulosic biofuels. Several recombinant cellulolytic yeast strains have been developed to reduce the cost of enzyme addition, but few of these strains are able to efficiently degrade crystalline cellulose due to their low cellulolytic activities. Here, by combining the cellulase ratio optimization with a novel screening strategy, we successfully improved the cellulolytic activity of a Saccharomyces cerevisiae strain displaying four different synergistic cellulases on the cell surface. The optimized strain exhibited an ethanol yield from Avicel of 57% of the theoretical maximum, and a 60% increase of ethanol titer from rice straw. To our knowledge, this work is the first optimization of the degradation of crystalline cellulose by tuning the cellulase ratio in a cellulase cell-surface display system. This work provides key insights in engineering the cellulase cocktail in a consolidated bioprocessing yeast strain. Biotechnol. Bioeng. 2017;114: 1201-1207. © 2017 Wiley Periodicals, Inc.
结晶纤维素是木质纤维素难以降解的主要原因之一，需要高剂量的纤维素酶才能消化，从而阻碍了纤维素生物燃料的经济可行性。已经开发了几种重组纤维素分解酵母菌株以降低添加酶的成本，但由于其纤维素分解活性低，这些菌株中很少有能够有效降解结晶纤维素的。在这里，通过将纤维素酶比例优化与一种新的筛选策略相结合，我们成功提高了在细胞表面展示四种不同协同纤维素酶的酿酒酵母菌株的纤维素分解活性。优化后的菌株从微晶纤维素中获得的乙醇产量为理论最大值的57%，从稻草中获得的乙醇滴度提高了60%。据我们所知，这项工作是首次通过在纤维素酶细胞表面展示系统中调整纤维素酶比例来优化结晶纤维素的降解。这项工作为在整合生物加工酵母菌株中设计纤维素酶混合物提供了关键见解。《生物技术与生物工程》2017年；114：1201 - 1207。©2017威利期刊公司
