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 …