Pilus

Gene

Electron transport chain

Cell biology

Biofilm

Bacteria

Biology

Gram-negative bacteria

Geobacter

Extracellular

Biochemistry

Electron transfer

Geobacter sulfurreducens

Genetics

Organic chemistry

Microbiology

Escherichia coli

Chemistry

Cell

Multicellular organism

Biophysics

Nature Communications

Long-distance extracellular electron transfer has been observed in Gram-negative bacteria and plays roles in both natural and engineering processes. The electron transfer can be mediated by conductive protein appendages (in short unicellular bacteria such as Geobacter species) or by conductive cell envelopes (in filamentous multicellular cable bacteria). Here we show that Lysinibacillus varians GY32, a filamentous unicellular Gram-positive bacterium, is capable of bidirectional extracellular electron transfer. In microbial fuel cells, L. varians can form centimetre-range conductive cellular networks and, when grown on graphite electrodes, the cells can reach a remarkable length of 1.08 mm. Atomic force microscopy and microelectrode analyses suggest that the conductivity is linked to pili-like protein appendages. Our results show that long-distance electron transfer is not limited to Gram-negative bacteria.

Long-distance electron transfer in a filamentous Gram-positive bacterium