Host: Jeff Fox with special guests, Gemma Reguera and Geoffrey Gadd.

Gemma Reguera of Michigan State University in East Lansing and Geoffrey Gadd of the University of Dundee in Scotland talk with Jeff Fox about their efforts, to probe some of the electrical properties of materials produced naturally by specific microorganisms. Thus, Geobacter bacteria make protein filaments, called pili, that act as nanowires, transporting 1 billion electrons per second, according to Reguera and her collaborators. Analytic evidence suggests that the electrons move along these proteins by a thermally activated, multistep hopping mechanism, enabling these bacteria to draw electrons from the extracellular milieu.

Meanwhile, the fungus Neurospora crassa can transform manganese into a mineral composite with favorable electrochemical properties. The fungal cells produce filaments that take up manganese, which after heat treatment forms structures that have electrochemical properties that are suitable for use in supercapacitors or lithium-ion batteries. The carbonized fungal biomass-mineral composite has excellent cycling stability and retains more than 90% capacity after 200 cycles, according to Gadd and his collaborators.

This story was featured in the June 2016 issue of Microbe Magazine.

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