Proteomic analysis of the electron uptake pathway of Rhodopseudomonas palustris CGA009 under different cathodic potentials

Abstract

Microbial electrosynthesis can convert greenhouse gas CO2 into value-added chemicals at room temperature and mild conditions, and the efficiency of its reaction is closely dependent on the electrode potential and electron transport chain-related functional proteins. In this study, the photosynthetic bacterium Rhodopseudomonas palustris CGA009 was used to explore CO2 bioreduction behavior at different potentials (−0.2 V, −0.5 V, −0.8 V). Label-free quantitative proteomics was used to analyze the mechanism of microbial electron transfer. The results showed that the cathodic potential could positively affect the NAD(P)-binding domain-containing protein of R. palustris CGA009. Ubiquinone and other terpenoid-quinone biosynthesis pathways that are mainly responsible for NAD(P)-binding domain-containing proteins also showed an upregulating trend in the KEGG analysis. The electrons are transferred to the photosynthetic chain through the B800-850 complex to collect light energy, and then the photosynthetic reaction center uses this energy to generate a proton gradient for transmembrane transport, allowing R. palustris CGA009 to use electrons for the fixation process of CO2. Our results enlighten the role of proteins in electron transfer chain of microbial electrosynthesis and provide an insight into how to regulate the microbial process to produce value-added chemicals.