Shewanella oneidensis uses an electron-shuttling conduit made up of proteins to live off of metal in minerals such as this hematite. |
Bacteria
called Shewanella can use metal ions in place of oxygen to live and
grow. In the process, Shewanella can transform some metals and trap them
in minerals, a useful skill for engineers who want to stop radioactive
or toxic metals from migrating in soil or groundwater. The bacteria also
help cycle metals used as nutrients through the biosphere.
But
bacteria can’t inhale solid metal like humans breathe oxygen. Instead
of lungs, Shewanella send out tiny wires that contact metals and
minerals. Within these wires are proteins that pass electrons outward,
but no one knows what these proteins look like or how exactly they work
together in a large complex.
Now,
a collaborative research team from the University of East Anglia and
Pacific Northwest National Laboratory have determined the structure of
the first of these protein components, providing insights into how
bacteria live off minerals and rocks.
In
addition to cleaning up legacy radioactive waste, the information will
help researchers tap bacteria to generate currents in fuel cells or for
applications in synthetic biology. Researchers performed some of the
work, which they reported in the Proceedings of the National Academy of
Sciences’ Early Edition, using instruments and expertise at EMSL, the
Department of Energy’s Environmental Molecular Sciences Laboratory on
the PNNL campus.
Report at the University of East Anglia.
Study abstract: Structure of a bacterial cell surface decaheme electron conduit
