Novel electron transfer pathways in Ralstonia eutropha

特征良好的革兰氏阴性细菌富养罗尔斯通氏菌能够利用广泛的异养碳源，但它以其在化能自养条件下固定CO2的能力而闻名。由于其灵活的代谢和越来越多的基因工程工具的可用性，它收到了生物技术应用的快速增长的兴趣。事实上，经过代谢工程改造的R.已经显示真养型菌株在自养条件下产生各种化学品和生物聚合物。然而，基于H2/O2的自养培养的扩大是有风险的，因为可能形成爆炸性气体混合物（氢氧，“Knallgas”），这导致严格的安全要求。此外，由于CO2固定酶RuBisCO的加氧酶副反应，在O2存在下CO2固定效率较低。这些问题可以通过使用替代的电子受体取代O2来规避。在这个建议中，生物电化学系统（BES）将被调查关于其使用作为细胞外电子受体。此外，可逆性的新的电子转移系统将探讨其潜力被利用在阴极驱动的电合成方法。在这个项目中，伦茨/弗里林斯多夫小组（R. eutropha）和Holtmann组（生物化学和电化学工程，用R. eutropha）将被组合以连接R.利用合适的电极构建一个新型、安全、通用和高效的生产平台。

The well-characterized Gram-negative bacterium Ralstonia eutropha is capable in utilizing a wide array of heterotrophic carbon sources, but it is renowned for its ability to fix CO2 under chemolithoautotrophic conditions. Due to its flexible metabolism and the increasing availability of tools for its genetic engineering, it receives rapidly growing interest for biotechnological application. In fact, metabolically engineered R. eutropha strains have already been shown to produce various chemicals and biopolymers under autotrophic conditions. Nevertheless, upscaling of H2/O2-based autotrophic cultivation is risky due to potential formation of explosive gas mixtures (oxyhydrogen, “Knallgas”), which results in rigorous safety requirements. Furthermore, the CO2 fixation efficiency is lower in the presence of O2, due to an oxygenase side reaction of the CO2-fixing enzyme RuBisCO. These issues can be circumvented by the use of alternative electron acceptors substituting O2. In this proposal, a bioelectrochemical system (BES) will be investigated with regard to its use as an extracellular electron acceptor. Furthermore, reversibility of the novel electron transfer systems will be explored for their potential to be exploited in cathode-driven electrosynthesis approaches. In this the project, the expertise of the Lenz/Frielingsdorf group (microbiology, molecular biology and biochemistry of R. eutropha) and the Holtmann group (biochemical and electrochemical engineering, electrobiotechnological production processes with R. eutropha) will be combined to connect the cellular redox metabolism of R. eutropha with suitable electrodes to establish a novel, safe, versatile, and highly efficient production platform.