Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 1/26/2010
Publication Date: N/A
Technical Abstract: Microbial fuel cells (MFCs) often use biological processes to generate electrons from organic material contained in the anode chamber and abiotic processes employing atmospheric oxygen as the oxidant in the cathode chamber. This study investigated the accumulation of an oxidant in bacterial cultures and examined the performance of this oxidant in the cathode chamber of a MFC. The MFC was a two-chambered cell with a stainless steel anode and an uncoated carbon cathode. Chambers were separated by a proton exchange membrane. The oxidant is produced by log phase cells of Burkholderia cenocepacia; is heat stable (121°C); has a molecular weight below 1 kD; oxidizes the dye 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS); and is soluble in water, ethanol or methanol. Its structure is unknown. The oxidant producing microorganism was identified as B. cenocepacia via FAME profile, 16S rRNA gene sequence data, and cellular characterization studies. The B. cenocepacia oxidizer performed better as a cathodic oxidizer than atmospheric oxygen or ferricyanide. MFC voltage (1000 ohm load) was 11 times higher with the B. cenocepacia oxidizer in the cathode chamber than with atmospheric oxygen (635 mm bar) and 2.9 times higher than with ferricyanide (0.02%). A mediator, ABTS, was required. Microorganisms that produce oxidizers might be used in bio-cathodes to improve the electrical output of MFCs.