Microbial community dynamics and electron transfer of a biocathode in microbial fuel cells

Abstract

Microbial community dynamics and its electron transfer process within a biocathode in a microbial fuel cell (MFC) were investigated in this study. The MFC was operated steadily over 400 days, and the power density reached 1.92 and 10.27 W/m 3 based on the reduction of nitrate and oxygen, respectively. The six major groups of the clones that were categorized among the 26 clone types were Proteobacteria, Bacteroidetes, Actinobacteria, Planctomycetes, Firmicutes and uncultured bacteria. Microbial community dynamics showed that Betaproteobacteria was replaced by Gammaproteobacteria as the most abundant division among all the clone types with a percentage of 48.86% in the cathode compartment, followed by 20.45% of uncultured bacteria, 17.05% of Bacteroidetes, and others. Distinct oxidation and reduction peaks could be observed in the profiles of cathodic effluent during the cyclic and differential pulse voltammetry tests. It confirmed that nitrate and oxygen reduction in the cathode compartment could be significantly enhanced by the presence of microbes, which are able to excrete metabolites to assist the electron transfer process either in the anode or in the cathode compartment.

Kinetics and gene diversity of denitrifying biocathode in biological electrochemical systems

“…Previously, the 16S rRNA gene-based phylogenic information of microbial consortia for cathodic denitrication through sequencing analysis have been studied, and Bacteroidetes, Proteobacteria, Firmicutes, Chloroexi, and Planctomycetes are reported as ve typical dominant phyla for denitrifying biocathodes. [15][16][17][18] Classes of Alphaproteobacteria, Anaerolineae, and Phycisphaerae may benet the performance of current production and nitrate removal. 18 Nevertheless, if only phylogenic information is used, then major functional denitriers in the microbial consortia of cathodic biolms can't be specied.…”

Performance and recent improvement in microbial fuel cells for simultaneous carbon and nitrogen removal: A review

“…The direct electron transfer mechanism was demonstrated with Geobacter species that were able to retrieve electrons directly from a graphite electrode, and used these electrons to reduce nitrate to nitrite (Gregory et al, 2004). Besides pure-culture systems, electron transfer has also been demonstrated to be involved in transformation of nitrate to N 2 in mixed-culture biocathodes (Chen et al, 2010;Zhu et al, 2013). While some bacteria perform direct electron transfer, some microorganisms can excrete redox-active compounds to carry out mediated electron transfer with electrodes.…”

Adding Zero-Valent Iron to Enhance Electricity Generation during MFC Start-Up

“…In recent years, many metals and their oxides were used to modify the cathode or anode of MFCs in an attempt to improve the ability to transfer electrons in reactors. In MFCs, the pass-way of the anode's extracellular electrons transfer can be divided into direct electron transfer and indirect electron transfer [9][10][11]. The former is transferred by the microbial extracellular cytochrome or "nanowires" "nanowires" while a soluble redox mediator is needed in the latter.…”