Microbial Community Characterization on Polarized Electrode Surfaces

Microbes are an integral part of any bioelectrochemical system (BES). In pure-culture systems, they are involved in catalyzing the transfer of electrons to an anode or from a cathode. In mixed cultures, in addition to these exoelectrogenic and exoelectrotrophic populations, there may be community members involved in other metabolisms that indirectly assist electrochemical activity (e.g., by converting a complex substrate into acetate) or compete with and impair electrochemical reactions (e.g., diverting acetate to methane). A thorough understanding of these systems and the accurate interpretation of system performance often require the characterization of the microbial communities that establish on either electrode, or perhaps even in suspension or on other reactor surfaces. The BES research community has used a variety of techniques to study microbial populations and communities. This chapter focuses on nucleic acid-based methods for community characterization, primarily 16S rRNA and 16S rRNA gene-targeted techniques (although they could be adapted to study other genes), which is consistent with the majority of BES ecology studies.