The researchers studied microbial nanowires, protein filaments that bacteria use naturally to make electrical connections with other microbes or minerals.
"Microbial nanowires are a revolutionary electronic material with substantial advantages over man-made materials,” Derek Lovley explains. “Chemically synthesising nanowires in the lab requires toxic chemicals, high temperatures or expensive metals.
“By contrast, natural microbial nanowires can be mass-produced at room temperature from inexpensive renewable feedstocks in bioreactors with much lower energy inputs."
The lab looked at the protein filaments of Geobacter species and found a range in conductivities. One species, Geobacter metallireducens produced nanowires 5000 times more conductive than the G. sulfurreducens wires the team had originally been studying.
To create Geobacter metallireducens, the researchers took the gene for the protein that assembles into microbial nanowires and inserted it into G. sulfurreducens. The result is a genetically modified G. sulfurreducens that expresses the G. metallireducens protein, making nanowires much more conductive.
"We have found that G. sulfurreducens will express filament genes from many different types of bacteria,” says Lovley. “This makes it simple to produce a diversity of filaments in the same microorganism and to study their properties under similar conditions."
"With this approach, we hope to see what is out there in terms of useful conductive materials," he adds.
The high conductivity of the G. metallireducens nanowires suggests they may be an attractive material for the construction of conductive materials, electronic devices and sensors for medical or environmental applications.
