School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, PR China; Hefei National Laboratory for Physical Science at the Microscale, Hefei, Anhui 230026, PR China.
School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, PR China.
Bioresour Technol. 2019 Feb;273:220-230. doi: 10.1016/j.biortech.2018.11.018. Epub 2018 Nov 7.
Lactic acid is an important industrial product and the production from inexpensive and renewable lignocellulose can reduce the cost and environmental pollution. In this study, a Kluyveromyces marxianus strain which produced lactic acid efficiently from corncob was constructed. Firstly, two of six different lactate dehydrogenases, which from Plasmodium falciparum and Bacillus subtilis, respectively, were proved to be effective for l-lactic acid production. Then, five single genetic modifications were conducted. The overexpression of Saccharomyces cerevisiae proton-coupled monocarboxylate transporter, K. marxianus 6-phosphofructokinase, or disruption of K. marxianus putative d-lactate dehydrogenase enhanced the l-lactic acid accumulation. Finally, the strain YKX071, obtained via combination of above effective genetic engineering, produced 103.00 g/L l-lactic acid at 42 °C with optical purity of 99.5% from corncob residue via simultaneous saccharification and co-fermentation. This study first developed an effective platform for high optical purity l-lactic acid production from lignocellulose using yeast with inexpensive nitrogen sources.
乳酸是一种重要的工业产品，用廉价且可再生的木质纤维素生产乳酸可以降低成本和环境污染。本研究构建了一株能够从玉米芯高效生产乳酸的马克斯克鲁维酵母（Kluyveromyces marxianus）菌株。首先，从疟原虫（Plasmodium falciparum）和枯草芽孢杆菌（Bacillus subtilis）中分别筛选出的两种不同的乳酸脱氢酶中的两种被证明可以有效用于 L-乳酸的生产。然后，进行了五次单基因修饰。过表达酿酒酵母（Saccharomyces cerevisiae）质子偶联单羧酸转运蛋白、马克斯克鲁维酵母 6-磷酸果糖激酶，或敲除马克斯克鲁维酵母潜在的 D-乳酸脱氢酶均增强了 L-乳酸的积累。最后，通过组合以上有效的基因工程手段，获得的 YKX071 菌株在 42°C 下，以玉米芯废渣为原料，通过同步糖化共发酵，可生产 103.00g/L 的 L-乳酸，光学纯度达 99.5%。本研究首次开发了一种利用酵母以廉价氮源从木质纤维素生产高光学纯度 L-乳酸的有效平台。
