Multiple paths of electron flow to current in microbial electrolysis cells fed with low and high concentrations of propionate

Hari Ananda Rao, Krishna Katuri, Eduardo Gorron, Bruce E. Logan, Pascal Saikaly

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Microbial electrolysis cells (MECs) provide a viable approach for bioenergy generation from fermentable substrates such as propionate. However, the paths of electron flow during propionate oxidation in the anode of MECs are unknown. Here, the paths of electron flow involved in propionate oxidation in the anode of two-chambered MECs were examined at low (4.5 mM) and high (36 mM) propionate concentrations. Electron mass balances and microbial community analysis revealed that multiple paths of electron flow (via acetate/H2 or acetate/formate) to current could occur simultaneously during propionate oxidation regardless of the concentration tested. Current (57–96 %) was the largest electron sink and methane (0–2.3 %) production was relatively unimportant at both concentrations based on electron balances. At a low propionate concentration, reactors supplemented with 2-bromoethanesulfonate had slightly higher coulombic efficiencies than reactors lacking this methanogenesis inhibitor. However, an opposite trend was observed at high propionate concentration, where reactors supplemented with 2-bromoethanesulfonate had a lower coulombic efficiency and there was a greater percentage of electron loss (23.5 %) to undefined sinks compared to reactors without 2-bromoethanesulfonate (11.2 %). Propionate removal efficiencies were 98 % (low propionate concentration) and 78 % (high propionate concentration). Analysis of 16S rRNA gene pyrosequencing revealed the dominance of sequences most similar to Geobacter sulfurreducens PCA and G. sulfurreducens subsp. ethanolicus. Collectively, these results provide new insights on the paths of electron flow during propionate oxidation in the anode of MECs fed with low and high propionate concentrations.
Original languageEnglish (US)
Pages (from-to)5999-6011
Number of pages13
JournalApplied Microbiology and Biotechnology
Volume100
Issue number13
DOIs
StatePublished - Mar 3 2016

Fingerprint Dive into the research topics of 'Multiple paths of electron flow to current in microbial electrolysis cells fed with low and high concentrations of propionate'. Together they form a unique fingerprint.

Cite this