Abstract
Metal reduction assays are traditionally used to select and characterize electrochemically active bacteria (EAB) for use in microbial fuel cells (MFCs). However, correlating the ability of a microbe to generate current from an MFC to the reduction of metal oxides has not been definitively established in the literature. As these metal reduction assays may not be generally reliable, here we describe a fourโ to nineโwell prototype high throughput voltageโbased screening assay (VBSA) designed using MFC engineering principles and a universal cathode. Bacterial growth curves for Shewanella oneidensis strains DSP10 and MRโ1 were generated directly from changes in open circuit voltage and current with five percent deviation calculated between each well. These growth curves exhibited a strong correlation with literature doubling times for Shewanella indicating that the VBSA can be used to monitor distinct fundamental properties of EAB life cycles. In addition, eight different organic electron donors (acetate, lactate, citrate, fructose, glucose, sucrose, soluble starch, and agar) were tested with S. oneidensis MRโ1 in anode chambers exposed to air. Under oxygen exposure, we found that current was generated in direct response to additions of acetate, lactate, and glucose. Biotechnol. Bioeng. 2009;102: 436โ444. ยฉ 2008 Wiley Periodicals, Inc.