Microbial population and functional dynamics associated with surface potential and carbon metabolism

Abstract

Microbial extracellular electron transfer (EET) to solid surfaces is an important reaction for metal reduction occurring in various anoxic environments. However, it is challenging to accurately characterize EET-active microbial communities and each member's contribution to EET reactions because of changes in composition and concentrations of electron donors and solid-phase acceptors. Here, we used bioelectrochemical systems to systematically evaluate the synergistic effects of carbon source and surface redox potential on EET-active microbial community development, metabolic networks and overall electron transfer rates. The results indicate that faster biocatalytic rates were observed under electropositive electrode surface potential conditions, and under fatty acid-fed conditions. Temporal 16S rRNA-based microbial community analyses showed that Geobacter phylotypes were highly diverse and apparently dependent on surface potentials. The well-known electrogenic microbes affiliated with the Geobacter metallireducens clade were associated with lower surface potentials and less current generation, whereas Geobacter subsurface clades 1 and 2 were associated with higher surface potentials and greater current generation. An association was also observed between specific fermentative phylotypes and Geobacter phylotypes at specific surface potentials. When sugars were present, Tolumonas and Aeromonas phylotypes were preferentially associated with lower surface potentials, whereas Lactococcus phylotypes were found to be closely associated with Geobacter subsurface clades 1 and 2 phylotypes under higher surface potential conditions. Collectively, these results suggest that surface potentials provide a strong selective pressure, at the species and strain level, for both solid surface respirators and fermentative microbes throughout the EET-active community development.

Anodic and cathodic microbial communities in single chamber microbial fuel cells

“…However a recent study demonstrated that different Geobacter clades and different microbial associations were linked to specific potentials. In fact, Geobacter metallireducens clade appeared to be associated with more negative potentials, while Geobacter clades 1 and 2 were observed at more positive potentials [34]. The effect of the electrode potential on the cathodic communities is not well described.…”

Carbon-Based Air-Breathing Cathodes for Microbial Fuel Cells

“…The biofilm acts as a catalyst for the metabolism of unrefined substrates (organic matter), during which electrons, protons, and other organic compounds are released. An understanding of the anodic reaction mechanism, together with an improvement of the electron transfer and the biofilm growth needs to be addressed to achieve an increased power density [20][21][22][23][24].…”

Resilience, Dynamics, and Interactions within a Model Multispecies Exoelectrogenic-Biofilm Community

“…Recently, many studies were carried out to expand the application of BESs and increase the efficiency of electricity production (9)(10)(11). One strategy is to understand and steer the microbial community on electrode surfaces (12). We are far from understanding the role of individual groups of microorganisms that thrive on anode surfaces in nonaxenic systems.…”