Title: Real-time monitoring of subsurface microbial metabolism with graphite electrodes

Abstract

Monitoring in situ microbial activity in anoxic submerged soils and aquatic sediments can be labor intensive and technically difficult, especially in dynamic environments in which a record of changes in microbial activity over time is desired. Microbial fuel cell concepts have previously been adapted to detect changes in the availability of relatively high concentrations of organic compounds in waste water but, in most soils and sediments, rates of microbial activity are not linked to the concentrations of labile substrates, but rather to the turnover rates of the substrate pools with steady state concentrations in the nM-μ M range. In order to determine whether levels of current produced at a graphite anode would correspond to the rates of microbial metabolism in anoxic sediments, small graphite anodes were inserted in sediment cores and connected to graphite brush cathodes in the overlying water. Currents produced were compared with the rates of [2-¹⁴C]-acetate metabolism. There was a direct correlation between current production and the rate that [2-¹⁴C]-acetate was metabolized to ¹⁴CO₂ and ¹⁴CH₄ in sediments in which Fe(III) reduction, sulfate reduction, or methane production was the predominant terminal electron-accepting process. At comparable acetate turnover rates, currents were higher in the sediments in which sulfate-reductionmore » or Fe(III) reduction predominated than in methanogenic sediments. This was attributed to reduced products (Fe(II), sulfide) produced at distance from the anode contributing to current production in addition to the current that was produced from microbial oxidation of organic substrates with electron transfer to the anode surface in all three sediment types. In conclusion, the results demonstrate that inexpensive graphite electrodes may provide a simple strategy for real-time monitoring of microbial activity in a diversity of anoxic soils and sediments.« less

Authors:

Wardman, Colin ^[1]; Nevin, Kelly P. ^[1]; Lovley, Derek R. ^[1]

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+ Show Author Affiliations

1. Univ. of Massachusetts, Amherst, MA (United States). Dept. of Microbiology

Publication Date:

Fri Nov 21 00:00:00 EST 2014

Research Org.:

Univ. of Massachusetts, Amherst, MA (United States). Dept. of Microbiology

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1441382

Grant/Contract Number:  

SC0006790

Resource Type:

Accepted Manuscript

Journal Name:

Frontiers in Microbiology

Additional Journal Information:

Journal Volume: 5; Journal ID: ISSN 1664-302X

Publisher:

Frontiers Research Foundation

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; subsurface sediments; microbial activity; anaerobic metabolism; electromicrobiology; aquatic sediments; biogeochemistry