Electrogenic potential of Enterococcus faecalis DWW1 isolated from the anodic biofilm of a dairy wastewater fed dual chambered microbial fuel cell

Abstract

In this investigation, a novel electrochemically active Gram positive bacterium was isolated from the biofilm of a dual chambered microbial fuel cell (MFC) flooded with dairy wastewater (DWW), and was annotated as Enterococcus faecalis DWW1 following the 16 s rRNA sequencing. The dye-reduction based electron-transfer activity (DREAM) assay was used as a simple criterion for evaluation of electrochemical activity (0.43) in the candidate microbe. The electrochemical activity of the strain DWW1 was characterized using cyclic voltametry (CV). CV studies revealed that the redox compound present in the DWW was exploited by the strain DWW1 for extracellular electron transfer towards anode. Current generation and chemical oxygen demand (COD) removal efficiencies of the strain DWW1 was examined following an optimum COD concentration of 1.440–1.665 kg COD/m3 and anolyte pH of 8 (maximum current density 258 mA/m2; power density 144 mW/m2, 220 Ω; COD removal efficiency 53.5%; coulombic efficiency 10.89%). Such observations revealed the potential of E. faecalis DWW1 towards DWW remediation and energy generation.