Inspiration from humans and microbes—and maybe a lot of luck: the “discovery” of Shewanella oneidensis MR-1 and extracellular electron transfer (EET)

ABSTRACT In the early 1980s, it was generally believed that insoluble electron acceptors were unavailable to bacteria unless they could be solubilized and transferred from the cell exterior to the cell membrane for use in redox reactions. Thus, many potentially active oxidants, such as metal oxides, while thermodynamically capable of acting as electron acceptors for respiration, were thought to not be available to bacteria or archaea. However, in 1988, with the isolation and characterization of Shewanella oneidensis MR-1 (so-called because it was the first metal-reducing bug we found) (C. R. Myers, K. H. Nealson, Science 240:1319–1321, 1988, https://doi.org/10.1126/science.240.4857.1319 ), it became clear that microbial manganese oxide reduction was indeed possible by a process now known as extracellular electron transfer or EET. In this minireview, I first discuss the isolation and characterization of S. oneidensis MR-1 and its progression from a “must be verified” status to its position as a model organism for the study of EET. This is followed by a summary of the roles that S. oneidensis MR-1 played in opening many previously unknown windows of microbial metabolism.