Evaluating Organic Acids As Oxidizable Fuels in R. Capsulatus-Based Bioelectrochemical Systems

Abstract

The development of microbial fuel cells (MFCs) for wastewater treatment has recently gained significant attention in the bioremediation and renewable energy industries. Bacteria can be integrated into the anodes of MFCs to oxidize organic wastes, simultaneously producing electrical current and decontaminating wastewater. The photoheterotrophic purple bacterium Rhodobacter capsulatus has demonstrated photo-catalyzed electron transfer to carbon electrodes via exogenous quinone redox mediators, and tolerance to high salinity, opening opportunities for solar-powered MFC systems for treatment of saline wastewater. While the consumption of malate by R. capsulatus has been electrochemically analyzed previously, in this project, alternative target carbon sources were examined in order to improve electrochemical performance of these R. capsulatus systems. A combination of electrochemical techniques and biological assays were used to evaluate the relative viability of malate, lactate, succinate and propionate as oxidizable fuels. Specifically, cyclic voltammetry and amperometry data demonstrated that R. capsulatus generates distinctive bio-photocurrent densities depending on the fuel metabolized. Bioanodes with immobilized R. capsulatus cells oxidizing lactate (9.49 ± 1.89 µA cm -2 ) as the fuel yielded the greatest mediated bio-photocurrent densities compared to the other fuels, while those metabolizing propionate (1.33 ± 0.18 µA cm -2 ) generated the smallest current densities. In tandem with electrochemistry methods, growth curve assays and RNA sequencing were performed to further delve into the biological effects of altering the carbon source.

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Identifiers

DOI

10.1149/ma2021-01421748mtgabs

Journal

ECS Meeting Abstracts

Year

2021