Enrichment of novel electroactive bacteria from sediments via potentiostatic growth

Sediments are usually enriched in electrochemically active microorganism via growth at defined potential, either in Microbial Fuel Cells or in potentiostat-controlled electrochemical cells. Despite the great microbial diversity of sediments from natural and man-made environment, most electrochemical enrichments select a small group of dissimilatory metal-reducing microorganisms. 

In this study, we aim to enrich novel electrochemically active strains in sediments from various equatorial environments.  Sediment inocula from urban waterways, industrial area, and mines were tested in long-term enrichment experiments at controlled anodic potentials. In addition to the conventional voltamperometric characterization, the biofilm, formed at the working electrode was subjected to Electrochemical Impedance Spectroscopy (EIS) over a wide range of potentials. EIS of the biofilms reveal several charge transfer routes at different potentials and with different characteristic times. Furthermore, EIS enable monitoring the long-term changes of the electroactive biofilm and quantifying the effect of biofilm accumulation on the conductivity of the biofilm/electrode interface. 

Electrochemical analysis is coupled with meta-genomic and meta-transcriptomics to reveal novel electrochemically active microorganisms and to understand their charge transfer mechanism. The understanding of the microbe/electrode interaction in the sediments will help controlling the dynamic of metal cycling in urban sediments. Furthermore, novel electrochemically active microorganism will find application in bioremediation and environmental sensing applications.