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Microbial activity influences electrical conductivity of biofilm anode.

ABSTRACT: This study assessed the conductivity of a Geobacter-enriched biofilm anode in a microbial electrochemical cell (MxC) equipped with two gold anodes (25?mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH gradient across the biofilm anode at 100?mM phosphate buffer (current density 2.38 A/m2) and biofilm conductivity (Kbio) was as high as 0.87?mS/cm. In comparison, an inner biofilm became acidic at 2.5?mM phosphate buffer in which dead cells were accumulated at ?80??m of the inner biofilm anode. At this low phosphate buffer, Kbio significantly decreased by 0.27?mS/cm, together with declined current density of 0.64 A/m2. This work demonstrates that biofilm conductivity depends on the composition of live and dead cells in the conductive biofilm anode.

SUBMITTER: Dhar BR

PROVIDER: S-EPMC7321815 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Microbial activity influences electrical conductivity of biofilm anode.

Dhar Bipro Ranjan BR Sim Junyoung J Ryu Hodon H Ren Hao H Santo Domingo Jorge W JW Chae Junseok J Lee Hyung-Sool HS

Water research 20171013

This study assessed the conductivity of a Geobacter-enriched biofilm anode in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH gradient across the biofilm anode at 100 mM phosphate buffer (current density 2.38 A/m<sup>2</sup>) and biofilm conductivity (K<sub>bio</sub>) was as high as 0.87 mS/cm. In comparison, an inner biofilm became acidic at 2.5 mM phosphate buffer in wh ...[more]

PMID: 29055828

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Project description:Microbial fuel cells (MFCs) generate energy while aiding the biodegradation of waste through the activity of an electroactive mixed biofilm. Metabolic cooperation is essential for MFCs' efficiency, especially during early colonization. Thus, examining specific ecological processes that drive the assembly of anode biofilms is highly important for shortening startup times and improving MFC performance, making this technology cost-effective and sustainable. Here, we use metagenomics to show that bioaugmentation of the anode surface with a taxonomically defined electroactive consortium, dominated by Desulfuromonas, resulted in an extremely rapid current density generation. Conversely, the untreated anode surface resulted in a highly stochastic and slower biofilm assembly. Remarkably, an efficient anode colonization process was obtained only if wastewater was added, leading to a nearly complete replacement of the bioaugmented community by Geobacter lovleyi Although different approaches to improve MFC startup have been investigated, we propose that only the combination of anode bioaugmentation with wastewater inoculation can reduce stochasticity. Such an approach provides the conditions that support the growth of specific newly arriving species that positively support the fast establishment of a highly functional anode biofilm.IMPORTANCE Mixed microbial communities play important roles in treating wastewater, in producing renewable energy, and in the bioremediation of pollutants in contaminated environments. While these processes are well known, especially the community structure and biodiversity, how to efficiently and robustly manage microbial community assembly remains unknown. Moreover, it has been shown that a high degree of temporal variation in microbial community composition and structure often occurs even under identical environmental conditions. This heterogeneity is directly related to stochastic processes involved in microbial community organization, similarly during the initial stages of biofilm formation on surfaces. In this study, we show that anode surface pretreatment alone is not sufficient for a substantial improvement in startup times in microbial fuel cells (MFCs), as previously thought. Rather, we have discovered that the combination of applying a well-known consortium directly on the anode surface together with wastewater (including the bacteria that they contain) is the optimized management scheme. This allowed a selected colonization process by the wastewater species, which improved the functionality relative to that of untreated systems.

Dataset Information

Microbial activity influences electrical conductivity of biofilm anode.

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Microbial activity influences electrical conductivity of biofilm anode.

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