Scientists at the University of Massachusetts Amherst have discovered that a bacterial strain known as Geobacter sulfurreducens permits electron transport across impressive distances. “In this species, the biofilm contains proteins that behave like a metal, conducting electrons over a very long distance, basically as far as you can extend the biofilm,” explains physicist Nikhil Malvankar active in the research.
Networks of nanowires fashioned from the bacteria strain offer material conductivity similar to that of synthetic conducting polymers. The discovery could revolutionize nanotechnology and bioelectronics, leading to the development of inexpensive, nontoxic nanomaterials that could be used for biosensors or solid-state electronics capable of interacting with biological systems.
From the press release:
Lead microbiologist Derek Lovley with physicists Mark Tuominen, Nikhil Malvankar and colleagues, say networks of bacterial filaments, known as microbial nanowires because they conduct electrons along their length, can move charges as efficiently as synthetic organic metallic nanostructures, and they do it over remarkable distances, thousands of times the bacterium’s length.
Networks of microbial nanowires coursing through biofilms, which are cohesive aggregates of billions of cells, give this biological material conductivity comparable to that found in synthetic conducting polymers, which are used commonly in the electronics industry.
Lovley says, “The ability of protein filaments to conduct electrons in this way is a paradigm shift in biology and has ramifications for our understanding of natural microbial processes as well as practical implications for environmental clean-up and the development of renewable energy sources.”
The discovery represents a fundamental change in understanding of biofilms, Malvankar adds. “In this species, the biofilm contains proteins that behave like a metal, conducting electrons over a very long distance, basically as far as you can extend the biofilm.”
Tuominen, the lead physicist, adds, “This discovery not only puts forward an important new principle in biology but in materials science. We can now investigate a range of new conducting nanomaterials that are living, naturally occurring, nontoxic, easier to produce and less costly than man-made. They may even allow us to use electronics in water and moist environments. It opens exciting opportunities for biological and energy applications that were not possible before.”
It was previously thought that such conduction would require a mechanism involving a series of other proteins known as cytochromes, with electrons making short hops from cytochrome to cytochrome. By contrast, the UMass Amherst team has demonstrated long-range conduction in the absence of cytochromes. The Geobacter filaments function like a true wire.
Abstract in Nature Nanotechnology: Tunable metallic-like conductivity in microbial nanowire networks