(438f) Expanding Whole Cell Catalysis Using Extracellular Electron Transfer

Metabolic engineering and whole-cell catalysis has facilitated the production of pharmaceuticals, fuels, and soft materials but is generally limited to well-defined metabolic pathways. Here, we'll discuss how extracellular electron transfer (EET) can be leveraged to expand the reaction scope of microbial catalysis by coupling metabolism to an extracellular catalytic cycle.¹ Specifically, we used the model electrogen Shewanella oneidensis to power a living radical polymerization via electron transfer to a metal catalyst. Using S. oneidensis, we achieved precise control over the molecular weight and polydispersity of a bioorthogonal polymer while non-electroactive organisms, such as E. coli, showed no significant activity. We also found that polymerization performance was a strong function of catalyst structure, bacterial metabolism, and specific electron transfer proteins. Finally, we describe how polymerization can be used to control hydrogel cross-linking in a genotypic-specific manner as well as our initial efforts to transcriptionally regulate relative flux through EET pathways. Overall, our results suggest that manipulating extracellular electron transfer pathways may be a general strategy for expanding the synthetic reaction space available to microbes.

1. G. Fan, C. M. Dundas, A. J. Graham, N. A. Lynd, B. K. Keitz,* “Shewanella oneidensis as a Living Electrode for Controlled Radical Polymerization” Proc. Natl. Acad. Sci. U.S.A., 2018, 115, 4559-4564.