Xiberras Joeline, Klein Mathias, de Hulster Erik, Mans Robert, Nevoigt Elke
Department of Life Sciences and Chemistry, Jacobs University Bremen gGmbH, Bremen, Germany.
Department of Biotechnology, Delft University of Technology, Delft, Netherlands.
Front Bioeng Biotechnol. 2020 Jun 26;8:566. doi: 10.3389/fbioe.2020.00566. eCollection 2020.
Previously, our lab replaced the endogenous FAD-dependent pathway for glycerol catabolism in by the synthetic NAD-dependent dihydroxyacetone (DHA) pathway. The respective modifications allow the full exploitation of glycerol's higher reducing power (compared to sugars) for the production of the platform chemical succinic acid (SA) via a reductive, carbon dioxide fixing and redox-neutral pathway in a production host robust for organic acid production. Expression cassettes for three enzymes converting oxaloacetate to SA in the cytosol ("SA module") were integrated into the genome of -DHA, an optimized CEN.PK derivative. Together with the additional expression of the heterologous dicarboxylic acid transporter DCT-02 from , a maximum SA titer of 10.7 g/L and a yield of 0.22 ± 0.01 g/g glycerol was achieved in shake flask (batch) cultures. Characterization of the constructed strain under controlled conditions in a bioreactor supplying additional carbon dioxide revealed that the carbon balance was closed to 96%. Interestingly, the results of the current study indicate that the artificial "SA module" and endogenous pathways contribute to the SA production in a highly synergistic manner.
此前，我们实验室通过合成的依赖NAD的二羟基丙酮（DHA）途径，取代了[具体生物]中甘油分解代谢的内源性依赖FAD的途径。这些相应的修饰使得能够充分利用甘油更高的还原能力（与糖类相比），通过一条还原、固定二氧化碳且氧化还原中性的途径，在对有机酸生产具有稳健性的生产宿主中生产平台化学品琥珀酸（SA）。将三种在胞质溶胶中把草酰乙酸转化为SA的酶的表达盒（“SA模块”）整合到了优化的CEN.PK衍生物[具体生物]-DHA的基因组中。连同来自[具体生物]的异源二羧酸转运蛋白DCT-02的额外表达，在摇瓶（分批）培养中实现了最大SA滴度为10.7 g/L，甘油产率为0.22±0.01 g/g。在供应额外二氧化碳的生物反应器中，在受控条件下对构建菌株进行表征，结果表明碳平衡达到了96%。有趣的是，当前研究结果表明，人工“SA模块”和内源性途径以高度协同的方式促进了SA的生产。
