Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea.
Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea.
J Biotechnol. 2018 Jan 20;266:27-33. doi: 10.1016/j.jbiotec.2017.12.001. Epub 2017 Dec 5.
An efficient production system for optically pure l- and d-lactic acid (LA) from Jerusalem artichoke tuber powder (JAP) was developed by metabolic engineering of Kluyveromyces marxianus. To construct LA-producing strains, the ethanol fermentation pathway of K. marxianus was redirected to LA production by disruption of KmPDC1 and expression of l- and d-lactate dehydrogenase (LDH) genes derived from Lactobacillus plantarum under the control of the K. marxianus translation elongation factor 1α promoter. To further increase the LA titer, the l-LA and d-LA consumption pathway of host strains was blocked by deletion of the oxidative LDH genes KmCYB2 and KmDLD1. The recombinant strains produced 130g/L l-LA and 122g/L d-LA by direct fermentation from 230g/L JAP containing 140g/L inulin, without pretreatment or nutrient supplementation. The conversion efficiency and optical purity were ≫>95% and ≫>99%, respectively. This system using JAP and the inulin-assimilating yeast K. marxianus could lead to a cost-effective process for the production of LA.
通过对马克斯克鲁维酵母的代谢工程改造，开发了一种从菊芋块茎粉（JAP）高效生产光学纯左旋乳酸（LA）和右旋乳酸（d-LA）的生产系统。为构建生产 LA 的菌株，通过敲除 KmPDC1 并表达来自植物乳杆菌的 l-和 d-乳酸脱氢酶（LDH）基因，将马克斯克鲁维酵母的乙醇发酵途径重新定向为 LA 生产，该基因受 K. marxianus 翻译延伸因子 1α 启动子的控制。为了进一步提高 LA 产量，通过缺失宿主菌株的氧化 LDH 基因 KmCYB2 和 KmDLD1 阻断了 l-LA 和 d-LA 的消耗途径。重组菌株直接从 230g/L 的 JAP 发酵生产 130g/L 的 l-LA 和 122g/L 的 d-LA，JAP 中含有 140g/L 的菊糖，无需预处理或营养补充。转化率和光学纯度分别为 ≫>95%和 ≫>99%。该系统使用 JAP 和可利用菊糖的酵母 K. marxianus 可以为 LA 的生产提供一种具有成本效益的工艺。
