Electroactive microorganisms in bioelectrochemical systems.

Abstract

A vast array of microorganisms from all three domains of life can produce electrical current and transfer electrons to the anodes of different types of bioelectrochemical systems. These exoelectrogens are typically iron-reducing bacteria, such as Geobacter sulfurreducens, thatproduce high power densities at moderate temperatures. With the right media and growthconditions, many other microorganisms ranging from common yeasts to extremophiles such ashyperthermophilic archaea can also generate high current densities. Electrotrophic microorganisms that grow by using electrons derived from the cathode are less diverse and haveno common or prototypical traits, and current densities are usually well below those reported for model exoelectrogens. However, electrotrophic microorganisms can use diverse terminal electron acceptors for cell respiration, including carbon dioxide, enabling a variety of novel cathode-driven reactions. The impressive diversity of electroactive microorganisms and theconditions in which they function provide new opportunities for electrochemical devices, such as microbial fuel cells that generate electricity or microbial electrolysis cells that produce hydrogen or methane.