Toward Natural and Engineered Microbial-Electronic Systems

Microorganisms are unsurpassed as materials: they self-assemble and self-repair from common non-precious materials; perform a wide range of biosynthetic processes, sense and respond to chemical and physical changes to their environment; harvest, store, release and transform chemical, light, and electrical energy; and self-organize into rugged structures. Some microorganisms are able to directly link internal electron consuming or generating metabolic processes with electron donors or acceptors residing outside the cell through a process called extracellular electron transfer (EET). Microbial EET sets the stage for microbial-based electronic systems when electrodes are used as the electron donor and acceptor, enabling precise -flick of a switch- control over the linked process. It also provides fertile ground for synthetic biology approaches to achieve direct electronic control over engineered processes, such as gene regulation and carbon fixation (converting CO2 to  fuel for a carbon neutral economy), and to impart EET to microorganisms that possess desired processes but lack the ability to perform EET. Here I will describe microbial EET, microbial electrochemistry (the study of microbial EET at electrodes) and its application to understand how EET occurs through natural microbial systems (such as how oxidant limited cells buried deep in a biofilm can still respire oxygen), synthetic biology and microbial EET, and a microbial-biofilm based rechargeable battery my colleagues and I are developing.