[Response of microbial fuel cell anodic microbial communities to substrate switch of lactate-propionate-lactate]

To study the effect of substrates variation on the electricity production of microbial fuel cell (MFC) and anodic microbial communities.

An MFC was started up and operated by feeding in turn with lactate, then with propionate and finally with lactate. The anodic microbial communities were monitored by using culture-independent microbial molecular ecological techniques.

The switch of substrates markedly affected the power efficiency of MFC. It required relatively long time to recover the electricity generation capability as the substrate was switched. The substrates switch also changed the microbial community structure. Anaeromusa spp. , Pseudomonas spp. and Thiobacillus thioparus were dominated with lactate fed because they were enriched in the presence of lactate. When propionate was supplied as sole substrate, Dechloromonas spp. and Comamonas testosterone were selected. The electricity-producing bacteria, Geobacter spp. , were enriched by acetate from either lactate or propionate degradation. Hence, Geobacter spp. was an overlapping microbial population in the presence of the two different substrates.

A well correspondence between substrate and anodic microbial community was observed in MFC with switching substrates. To reduce the effect of substrate fluctuation on the MFC electricity production, more complex organic substrate should be provided as broader nutrients which could improve the functional overlap of populations and MFC stability.