Ability of a Haloalkaliphilic Bacterium Isolated from Soap Lake, Washington to Generate Electricity at pH 11.0 and 7% Salinity


A variety of anaerobic bacteria have been shown to transfer electrons obtained from organic compound oxidation to the surface of electrodes in microbial fuel cells (MFCs) to produce current. Initial enrichments for iron (III) reducing bacteria were set up with sediments from the haloalkaline environment of Soap Lake, Washington, in batch cultures and subsequent transfers resulted in a culture that grew optimally at 7.0% salinity and pH 11.0. The culture was used to inoculate the anode chamber of a MFC with formate as the electron source. Current densities up to 12.5 mA/m2 were achieved by this bacterium. Cyclic voltammetry experiments demonstrated that an electron mediator, methylene blue, was required to transfer electrons to the anode. Scanning electron microscopic imaging of the electrode surface did not reveal heavy colonization of bacteria, providing evidence that the bacterium may be using an indirect mode of electron transfer to generate current. Molecular characterization of the 16S rRNA gene and restriction fragment length profiles (RFLP) analysis showed that the MFC enriched for a single bacterial species with a 99% similarity to the 16S rRNA gene of Halanaerobium hydrogeniformans. Though modest, electricity production was achieved by a haloalkaliphilic bacterium at pH 11.0 and 7.0% salinity.


Biological Sciences


Missouri University of Science and Technology. Energy Research Development Center


This work was funded by the Missouri University of Science and Technolog's Energy Research and Development Center.

Keywords and Phrases

Electricity Production; Extremophiles; Generate Electricity; Halanaerobium hydrogeniformans; Haloalkaliphile; Microbial Fuel Cells (MFCs); Molecular Characterization; Scanning Electron Microscopic; Aromatic Compounds; Batch Cell Culture; Cyclic Voltammetry; Electrons; Genes; Lakes; RNA; Bacteria; Formic Acid; Methylene Blue; RNA 16S; Anoxic Conditions; Colonization; Electricity Generation; Electrode; Iron; Microbial Activity; Molecular Analysis; pH; Salinity; Scanning Electron Microscopy; Species Diversity; Anaerobic Bacterium; Bacterium; Bacterium Culture; Controlled Study; Cyclic Potentiometry; Electricity; Electrode; Electron; Electron Transport; Environment; Halanaerobium; Haloalkaliphilic Bacterium; Lake; Nonhuman; Nucleotide Sequence; Restriction Fragment; Sediment; United States; Soap Lake; Washington [United States]; Bacteria (Microorganisms); Bacteria; Bioelectric Energy Sources; Biofuels; Electrochemistry; Electrodes; Electrons; Energy-Generating Resources; Hydrogen-Ion Concentration; Iron; Lakes; Methylene Blue; Microscopy, Electron, Scanning; Phenotype; RNA, Ribosomal, 16S; Salts; Microbial Biofuel Cell

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Article - Journal

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© 2014 Taylor & Francis, All rights reserved.

Publication Date

01 Apr 2014

PubMed ID