(274b) Engineering Bioelectricity Production from Microbes for Applications in Living Electronics

Microbes act as living catalysts, capable of orchestrating the most intricate, multi-step reaction pathways. Bioengineers have harnessed the tunability and versatility of their metabolisms to realize diverse applications in synthesis and energy. The same advantages make microbes ideal for applications in bioelectronics such as electrosynthesis, fuel cells, and photovoltaics. However, the progress in these areas has been limited by the inefficient charge transfer across microbial outer membranes.

This presentation highlights our advancements in bioengineering pathways for extracellular charge transfer. We focus on bioelectricity production from both chemotrophs (E. coli) and heterotrophs (Synechocystis PCC 6803). In E. coli, we reconstitute the complete MtrCAB electron transfer pathway, native to S. oneidensis, through the heterologous expression of heme proteins spanning the inner membrane, outer membrane, and periplasmic space. When coupled to electrodes, the engineered E. coli demonstrate a three-fold increase in current produced from the oxidation of lactate compared to empty-vector controls. We further enhance the extracellular electron transfer through the concomitant biosynthesis of flavins. Similarly, in Synechocystis, we improve extracellular electron transfer through the heterologous expression of MtrA, enabling light-driven bioelectricity production. These advances enable energy generation from both organic waste and sunlight in the form of living fuel cells and living photovoltaics, respectively. Moreover, this work lays the framework for unexplored applications in light-powered and voltage-controlled microbial electrosynthesis through intracellular charge transfer.