| 초록 |
A lack of outer membrane proteins in Gram-positive bacteria suggests that electron transfers to electrode are impossible without soluble electron-carrying mediator. Although one of spore-forming Clostridium butyricum strain has been reported to be electrically active without the addition of a soluble mediator (Anaerobe, 2001, 7(6), 297-306), the mechanism of electron transfer between electrode and Gram-positive spore formers remains unexplained. Here, we show that the direct electron transfer from one of butyrate-producing Clostridium strain to a cathode. Without mediators, the current was consumed by the Clostridium strain at a cathode compartment of H-type bioelectrochemical reactor (BER) in which an anode oxidizes ferrous to ferric ion. Other tested strains, C. acetobutyricum and C. tyrobutyricum did not show current consumption without mediator. Increased reducing powers induced by electron supply to the Clostridium strain enhanced butyrate production up to 1.6 times. Also, biofilm formation was electrochemically driven on the surface of cathode, graphite felt. The study of electrochemical activity of Clostridium strain can help to understand interaction between Gram-positive spore former and electrode and to apply electricity for an electron donor to microbes. |
