Deciphering the mechanism of formate utilization in Rhodobacter capsulatus and its metabolic optimization

Abstract

Biorefining from formate to fuels and chemicals is an attractive way to address the current energy crisis and greenhouse effect, and it is also one of the key strategies to achieve carbon neutrality and sustainable industry development. Rhodobacter capsulatus, a kind of purple non-sulfur photosynthetic bacteria (PNSB), can grow efficiently on formate as the sole carbon source, which serves a good candidate for formate-based biorefinery. However, the exact mechanism for formate assimilation and metabolic regulation in R. capsulatus has not yet been elucidated, which greatly limits the application of formate-based biorefinery by R. capsulatus. To address the above bottlenecks, based on the previous studies about the comparative analysis of formate metabolic pathways in R. capsulatus, we will decipher the mechanism of formate assimilation through the transcriptomic analysis, gene knockouts to block the potential pathways, and the metabolic flux analysis with the ¹³C-label. Then, we will promote the formate assimilation pathways, and obtain the dominant mutant under the high formate concentration through laboratory adaptive evolution, to reveal the regulatory mechanism of the enhanced formate metabolism. Finally, we will take the bisabolene biosynthesis as an example to validate the performance of formate-based biorefinery by R. capsulatus. Our research will lay a foundation in elucidating the formate assimilation pathways in other PNSB, and provide the theoretical and technical support for promoting the development of formate-based biorefinery at an industrial-scale.