Proteomics Reveal the Effect of Exogenous Electrons on Electroactive Escherichia coli

Abstract

Microbial cells utilizing electricity to produce high-value fuels and chemicals are the foundation of the biocathodic bioelectrochemical system. However, molecular mechanisms of electron transfer and utilization have not been elucidated. In this work, Escherichia coli engineered by introducing the Mtr pathway from Shewanella oneidensis exhibited stronger electrochemical activity than control and could utilize exogenous electrons to stimulate metabolite profiles and boost succinate production in the bioelectrochemical system. Proteomic analysis and real-time PCR were performed to investigate the effect of exogenous electrons on electroactive E. coli. Bioinformatics analysis suggested that the proteins of molecular function associated with oxidoreductase activity, 4 iron, 4 sulfur([4Fe-4S]) cluster binding, iron-sulfur cluster binding, and metal cluster binding were positively affected by exogenous electrons. Moreover, mapping to the Kyoto Encyclopedia of Genes and Genomes pathway database showed that the up-regulated proteins were mainly involved in metabolic pathways of tricarboxylic acid cycle, pyruvate metabolism, and nitrogen metabolism pathway, providing support for the metabolic balance of microbial cells shifting toward reduced end-products due to electron utilization. Using a biochemical method, the ompF-overexpressed strain was employed to investigate the function of the channel protein. These findings provided a theoretical basis for further improving electron transfer and utilization efficiency, and contributed to the potential applications of the bioelectrochemical system.

A self-activating electron transfer antibacterial strategy: Co3O4/TiO2 P–N heterojunctions combined with photothermal therapy

“…54 Notably, the role of FMN/FAD and Mtr in the electron transfer process is critical. 35 Mtr serves as a porin-cytochrome complex, acting as an electron conduit, 60,61 whereas FMN/FAD acts as the flavoprotein's prosthetic group in complexes I and II, facilitating electron transfer from NADH to the ubiquinone pool. 62 The interaction between FMN and Mtr can be restricted by “redox switches”, that is, disulfide bonds present on the bacterial membrane which modulate the oxidative stress status.…”