Department of Agricultural Biotechnology, Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Republic of Korea.
Department of Food Science and Human Nutrition, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Bioresour Technol. 2017 Mar;228:355-361. doi: 10.1016/j.biortech.2016.12.042. Epub 2016 Dec 18.
Even though industrial yeast strains exhibit numerous advantageous traits for the production of bioethanol, their genetic manipulation has been limited. This study demonstrates that an industrial polyploidy Saccharomyces cerevisiae JHS200 can be engineered through Cas9 (CRISPR associated protein 9)-based genome editing. Specifically, we generated auxotrophic mutants and introduced a xylose metabolic pathway into the auxotrophic mutants. As expected, the engineered strain (JX123) enhanced ethanol production from cellulosic hydrolysates as compared to other engineered haploid strains. However, the JX123 strain produced substantial amounts of xylitol as a by-product during xylose fermentation. Hypothesizing that the xylitol accumulation might be caused by intracellular redox imbalance from cofactor difference, the NADH oxidase from Lactococcus lactis was introduced into the JX123 strain. The resulting strain (JX123_noxE) not only produced more ethanol, but also produced xylitol less than the JX123 strain. These results suggest that industrial polyploidy yeast can be modified for producing biofuels and chemicals.
尽管工业酵母菌株在生产生物乙醇方面表现出许多有利的特性，但它们的遗传操作一直受到限制。本研究表明，通过 Cas9（CRISPR 相关蛋白 9）为基础的基因组编辑可以对工业多倍体酿酒酵母 JHS200 进行工程改造。具体来说，我们生成了营养缺陷型突变体，并将木糖代谢途径引入营养缺陷型突变体中。正如预期的那样，与其他工程化的单倍体菌株相比，工程化菌株 (JX123) 增强了对纤维素水解物的乙醇生产能力。然而，JX123 菌株在木糖发酵过程中会产生大量的木糖醇作为副产物。假设木糖醇的积累可能是由于辅因子差异导致细胞内氧化还原失衡引起的，我们将乳球菌 Lactococcus lactis 的 NADH 氧化酶引入到 JX123 菌株中。结果表明，该菌株 (JX123_noxE) 不仅产生了更多的乙醇，而且产生的木糖醇也比 JX123 菌株少。这些结果表明，工业多倍体酵母可以被修饰以生产生物燃料和化学品。
