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Title: Increased electrical output when a bacterial ABTS oxidizer is used in a microbial fuel cell

Author
item Hunter, William
item Manter, Daniel

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2010
Publication Date: 2/1/2011
Citation: Hunter, W.J., Manter, D.K. 2011. Increased electrical output when a bacterial ABTS oxidizer is used in a microbial fuel cell. Current Microbiology. 62(2):633-638.

Interpretive Summary: Microbial fuel cells (MFCs) are an energy production technology that provides electrical energy from the microbial oxidation of organic compounds. In most MFCs oxygen us used in the cathode chamber. For the present study a bacterial oxidizer was investigated and its performance evaluated in a basic two-chambered. The bacteria the produced the oxidant was isolated from soil and identified as Burkholderia cenocepacia using molecular microbiological. This bacteria is a common soil microorganism. The oxidant was produced by log phase cells and was identified by its ability to oxidize the dye 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) or ABTS. The oxidizer has a molecular weight below 1 kD, was heat stable (121°C) and was soluble in ethanol. In a MFC with a 1000 ' load the oxidizer increased outperformed atmospheric oxygen as an oxidant. With the oxidizer cell voltage was 11 times higher than atmospheric. Organisms that produce and release oxidizers into the media may prove useful as bio-cathodes and may be used to improve the electrical output of MFCs.

Technical Abstract: Microbial fuel cells (MFCs) are a technology that provides electrical energy from the microbial oxidation of organic compounds. Most MFCs use oxygen as the oxidant in the cathode chamber. The present study examined the formation in culture of an unidentified bacterial oxidant and investigated the performance of this oxidant in a two-chambered MFC with a proton exchange membrane and an uncoated carbon cathode. DNA, FAME profile, and characterization studies identified the microorganism that produced the oxidant as Burkholderia cenocepacia. The oxidant was produced by log phase cells, oxidized the dye 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), had a molecular weight below 1 kD, was heat stable (121°C) and was soluble in ethanol. In a MFC with a 1000 ' load and ABTS as a mediator the oxidizer increased cell voltage 11 times higher than atmospheric oxygen and 2.9 times higher than that observed with ferricyanide in the cathode chamber. No increase in cell voltage was observed when no mediator was present. Organisms that produce and release oxidizers into the media may prove useful as bio-cathodes by improving the electrical output of MFCs.