Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
A bioelectrical reactor (BER) with anode and cathode cambers separated by a proton exchange membrane was designed and used for stimulation of butyrate production mediated by methyl viologen (MV) as an electron shuttle. A sucrose utilizing strain of Clostridium tyrobutyricum, BAS 7 was cultivated in a cathode compartment with 0.5 mM MV at constant cathode potential of -750 mV vs Ag/AgCl. C. tyrobutyricum is an acidogenic bacterium and produces butyrate, acetate, CO2, and H2 as main end-products. Butyrate production in MV (0.5 mM)-treated BAS 7 culture was increased 150(±6.5) % and gas formation was decreased up to 65(±3.2) % of untreated bacteria control. High value of g butyrate / g sucrose (product/substrate) in BER showed bioelectrosynthesis of butyrate, electricity-driven synthesis by C. tyrobutyricum. We constructed complete electron equivalent balances for untreated, MV-treated, and BER (MV as a mediator) system by measuring all e- sinks to know the stimulation mode of MV and BER on butyrate production and changed microbial metabolism driven by electrical current. This result shows external electron donors changed microbial metabolism and leaded valuable products of biofuel from electricity.