Engineered living conductive biofilms

Living conductive biofilms are biomaterials comprised of bacterial cells electrically connected to each other and to electrodes across multiple length scales. The properties of living conductive biofilms are due to the ability of some bacteria to form a network of charge carrying proteins across the cell membrane and through the biofilm matrix in a process called extracellular electron transfer. Such bacteria, known as electroactive bacteria, catalyze an array of reactions at electrodes not possible with nonliving conductive films due to the diverse range of their cellular metabolisms. Applications of natural living conductive biofilms include energy harvesting at the bottom of the ocean, bioremediation, and carbon capture for biosynthesis. Recent breakthroughs in bioengineering offer new tools to modify living conductive biofilms in order to improve on existing technologies, such as increasing the electrical current produced by a microbial fuel cell, or creating entirely new ones. For example, fully synthetic living conductive biofilms could be deployed as electrically responsive materials under conditions where natural electroactive bacteria cannot operate. In this chapter, we review our current state of understanding of natural conductive biofilms, tools and methods for studying conductive biofilms, and opportunities for bioengineering of these biomaterials.