Novel electron transfer pathways in Ralstonia eutropha

Cupriavidus necator (Ralstonia eutropha) is probably the best known aerobic H2 oxidizer and an ideal candidate for the production of high-value compounds from CO2 and electrical energy. Nevertheless, upscaling of H2/O2-based autotrophic cultivation is risky due to potential formation of explosive Knallgas mixtures, resulting in rigorous safety requirements. Furthermore, the CO2 fixation efficiency is lower in the presence of O2, which is due to the oxygenase side reaction of the CO2-fixing enzyme RuBisCO. These issues can be circumvented by using alternative terminal electron acceptors to substitute O2.
In this project, a bioelectrochemical system (BES) is being investigated with regard to its use as an extracellular electron acceptor that enables “anodic respiration”. Furthermore, reversibility of the novel electron transfer systems will be explored with respect to their potential use in cathode-driven electrosynthesis approaches. The expertise of the Lenz/Frielingsdorf group (microbiology, molecular biology and biochemistry of C. necator) and the Holtmann group (biochemical and electrochemical engineering, electrobiotechnological production processes with C. necator) will be combined to connect the cellular redox metabolism of C. necator with suitable electrodes to establish a novel, safe, versatile, and highly efficient production platform.

Project overview