Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes
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Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated “intact” sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress.
KeywordsHypersaline Microbial fuel cell Electricity Arsenate
Microbial fuel cell
We thank Suresh Seshadri and Martin Buehler of JPL for their enthusiastic support of this project. The following people helped in the laboratory: Jodi Switzer Blum, Stacy Bennett, Shelley Hoeft, Tom Kulp, Shaun Baesman, John Duff, and Larisa Yunerman. Thank you also to Charlie Ogle, Kelly Wrighton, and Cameron Thrash for assistance with microbial fuel cells. Kelly Wrighton and Chad Saltikov reviewed an early draft of this manuscript. Financial support was provided by USGS National Research Program, and NASA ASTID 2003.
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