Abstract: Most microbes use soluble electron donors and acceptors, but some can also use insoluble conductive substances/surfaces (called conductive substances/surfaces). This process is called extracellular electron transfer (EET). The directionality of electron flow during EET can be either outbound, where conductive substances/surfaces are used as electron acceptors via reductive EET (rEET), or inbound, where conductive substances/surfaces are used as electron donors via extracellular electron uptake (EEU).

rEET was noted nearly three decades ago, and numerous studies have revealed that it significantly contributes to the biogeochemical cycling of iron, manganese, other heavy metals, sulfur, nitrogen, and carbon. The mechanisms underlying rEET are known, and this knowledge has been used for many applications.

In contrast to rEET, EEU has come to fore only recently, and this newly discovered microbial capability is the focus of my laboratory’s research. In recent work, we show that this process can be performed by phototrophic microbes and that it is very common in nature. We are also using some of these microbes as chassis organisms for sustainable bioproduction.