Our research interests lie at the interface of physics, microbiology, and nanotechnology. This research is particularly focused on the the interface between biological and inorganic systems. From a basic biological physics standpoint, we study cell-surface interactions as well as the electronic and enzymatic activity of extracellular nanostructures, such as bacterial nanowires and redox-reactive vesicles involved in microbe-inorganic interactions. Our goal is to identify the genetic basis, molecular structure, and electronic transport mechanism(s) in such nanostructures. Armed with the basic physics, we harness this understanding towards a new generation of biotechnological devices that exploit extracellular electron transport in the areas of bioenergy, bioremediation, and biosynthesis of nanomaterials.

Living Conductors: Extracellular Electron Transport in Bacterial Nanowires

The recent discovery that metabolically diverse microorganisms produce electrically conductive appendages is rapidly reshaping our understanding of extracellular electron transfer in microbial communities. We’ve initiated an interdisciplinary research program to investigate the molecular building blocks and the basic physics of conduction in these bacterial nanowires. Our improved understanding of this topic has immense implications for physiology, ecology, bioenergy production, bioremediation, pathogenic biofilms, and signal transduction across the biological-inorganic interface. We are currently leading the way in biocompatible nanofabrication methods that address individual bionanowires. This work is highly interdisciplinary and our collaborations span the USC Departments of Biological Sciences, Earth Sciences, and the J. Craig Venter Institute.

Bioenergy from Microbial Fuel Cells

The ability of certain microorganisms to transfer electrons directly to solid surfaces enables the emerging technology of microbial fuel cells, where bacteria are used as catalysts to convert fuel to electricity. Understanding the electron transport physics at the biological-inorganic interface is critical to improving the power density of fuel cells that function directly by consuming biomass. Our objective is to understand how nanoscale microbial-surface interactions translate to the observable power output in these devices. To accomplish this goal, our approaches combine surface modification, scanning probe microscopy, nano-scale electrical characterization, and macro-scale electrochemical analysis. This work is part of a Multidisciplinary University Research Initiative (MURI) and is funded by the Air Force Office of Scientific Research. Click here to visit the project’s website.

Biological Routes to Nanomaterial Synthesis


We are working to understand and control the synthesis of inorganic nanostructures templated in the extracellular matrix of biofilms. In one recent demonstration, the bacterium Shewanella oneidensis MR-1 drives the synthesis of semiconductive arsenic sulfide nanotubes (pictured here). Our understanding of Shewanella’s genome and metabolism, coupled with our experience in nanomaterial synthesis and charaterization enables us to explore the molecular basis of nanotube formation, and the potential to synthesize other technologically important materials, such as cadmium sulfide. The production of nanomaterials by biological means opens the possibility of cheaper and more environmentally friendly manufacture of electronic materials.

New Imaging Techniques Research summary coming soon.

The Enzymatic Activity of Extracellular Nanostructures. Implications for Bioenergy and Bioremediation Research summary coming soon.