Now, Nielsen, who was not involved in the new study, is speculating about how microbes take best advantage of natural conductors around them. "With electric conductors around, it seems very attractive to exchange goods into a common and more liquid currency—electrons," he argues. "To get the full benefit of these mini electrodes, I imagine that the microbes may have developed structures to control the location of them and not just rely on coincidental contact," he adds.
That idea remains to be proved. In the meantime the new discovery suggests that microbes like G. sulfurreducens and T. denitrificans may build electric grids wherever they find themselves. After all, magnetite and other conducting minerals abound on Earth, and such metal-based grids, by allowing the long-distance transfer of electrons, would foster microbial growth. Humans may benefit from bacterial grid-building as well. Understanding how the microbes construct their grids may help us to build a better fuel cell to put that potential to work for us.