Adaptation of soil microbes during establishment of microbial fuel cell consortium fed with lactate
By Futamata, Hiroyuki; Bretschger, Orianna; Cheung, Andrea; Kan, Jinjun; Owen, Rubaba & Nealson, Kenneth H.
Published in Journal of Bioscience and Bioengineering
2013
Abstract
We report the development of microbial populations and changes in their electrochemical production during a 2-month study of a two-chamber microbial fuel cell (MFC). The original inoculum was taken from anaerobic enrichment cultures with soil as the inoculum, and lactate as the exogenous electron donor. Power density (PD), coulombic production (CP), and coulombic efficiency (CE) increased rapidly, reaching high values (320Â mWÂ m-3, 65Â Q, and 12.5%, respectively) in 12–16 days. Under these conditions, several major microbial taxa dominated the anode population. The medium solution in the cathode chamber decreased with aeration, resulting in a decrease in PD to 55Â mWÂ m-3 at day 20. Refilling the cathode chamber around day 30 resulted in restoration of the PD, CP and CE to values equal to or greater than those previously observed. However, after the change in conditions, a marked change in community structure was observed, and high levels of acetate were seen in the anode chamber of the fuel cell for the first time. At day 35, a series of lactate concentrations were used, beginning with low levels and increasing to the 20Â mM level originally used (day 46), the PD decreased but was stable at 150Â mWÂ m-3 and the acetate concentration in the anode stabilized at about 35Â mM. Under these conditions, new major population structures, which were closely related to Propionibacterium, Clostridium, and uncultured bacteria, were observed in the anode. These results suggested that the flexibility of community structure was important for sustainable electricity production.