Prolonged applied potential to anode facilitate selective enrichment of bio-electrochemically active Proteobacteria for mediating electron transfer: Microbial dynamics and bio-catalytic analysis

Prolonged application of poised potential to anode was evaluated to understand the influence of applied potentials [500 mV (E500); 1000 mV (E1000); 2000 mV (E2000)] on bio-electrogenic activity of microbial fuel cell (MFC) and the resulting dynamics in microbial community in comparison to control operation. E1000 system documented higher electrogenic activity (309 mW/m2) followed by E500 (143 mW/m2), E2000 (112 mW/m2) and control (65 mW/m2) operations. The improved power output at optimum applied potential (1000 mV) might be attributed to the enrichment of electrochemically active bacteria majorly belonging to the phylum Proteobacteria with less extent of Firmicutes which helped in effective electron (mediated) transfer through release of exogenous shuttlers. Improved bio-electrogenic activity due to enrichment at 1000 mV applied potential also correlated well with the observed cyctochrome-c peaks on the voltamatogram, lower ion ohmic losses and bio-electro kinetic analysis. Electric-shock at higher applied potential (E2000) resulted in the survival of less number of microbial species leading to lower electrogenesis.