Electron acceptor-limitation controls wastewater electrogenic biodegradation in G. sulfurreducens

GUTIERREZ-GARRAN, CRISTINA; BUSALMEN, JUAN PABLO; ESTEVE-NUÑEZ, ABRAHAM

Seville

Simposio; 20th SETAC Europe annual meeting; 2010

Classical anaerobic wastewater treatment involves the transformation of organic matter into short-chain organic acids, yielding acetate as main biodegradation product. This acetate can be further processed in a microbial fuel cell (MFC) able to convert acetate into electricity by means of electrogenic microorganisms. Fe(III)-reducing bacteria Geobacter sulfurreducens is the most suitable organism for this purpose, due to its biodegradation capacities and the ability to oxidise organic compounds whilst transferring electrons to MFC anodes [1]. Previous studies [1, 2] showed that the acetate/electron acceptor ratio is key for the coupling among oxidation and exocellular electron transfer while outermost membrane cytochromes establish the electrical wiring from G. sulfurreducens to the conducting surface[3]. For giving insights into this fact, we have analyzed acetate-limiting and acetate-excess chemostat cultures by combining Cyclic Voltammetry assays with outermost protein biochemical analysis. Furthermore, we have analyzed the metabolome of chemostat-growing cells in order evaluate the fluxome pattern for the optimal conversion of waste into current production. Our studies suggest a different electrogenic response regarding the substrate-limitation of these cells. We demonstrate the crucial role of outermost membranecytochromes for current production when the cells are cultured under electron acceptor-limiting conditions.