A bacteria's double life: living off both iron and electricity

September 25, 2015

Researchers at the RIKEN CSRS and the University of Tokyo have demonstrated that the bacterium Acidithiobacillus ferrooxidans can take electrons needed for growth directly from an electrode power source when iron—its already known source of energy—is absent. The study, published in Frontiers in Microbiology, shows that A. ferrooxidans can use direct uptake of electrons from an electrode to fuel the same metabolic pathway that is activated by the oxidation of diffusible iron (Fe2+) ions.

Researchers cultured A. ferrooxidans in an Fe2+-free environment and supplied an electrode with an electrical potential of +0.4 V, carbon-dioxide as a carbon source, and oxygen as an electron acceptor. The team found that these conditions created a current that originated from the electrode, and that the strength of the current depended on how many cells were attached to the electrode. Killing the cells with UV light immediately suppressed the current.

This research showed that the electricity could be the third energy following to the light and chemicals to support the food chain on the earth. It is expected to become an important knowledge for investigating the electrical ecosystem which is a hypothetical biosphere depending on electricity at the deep seabed.


Original article
Frontiers in Microbiology doi: 10.3389/fmicb.2015.00994
T. Ishii, S. Kawaichi, H. Nakagawa, K. Hashimoto, R. Nakamura,
"From Chemolithoautotrophs to Electrolithoautotrophs: CO2 Fixation by Fe(II)-Oxidizing Bacteria Coupled with Direct Uptake of Electrons from Solid Electron Sources".

Ryuhei Nakamura
Team Leader
Biofunctional Catalyst Research Team