Novel Methanobacterium Strain Induces Severe Corrosion by Retrieving Electrons from Fe0 under a Freshwater Environment

Methanogens capable of accepting electrons from Fe-0 cause severe corrosion in anoxic conditions. In previous studies, all iron-corrosive methanogenic isolates were obtained from marine environments. However, the presence of methanogens with corrosion ability using Fe-0 as an electron donor and their contribution to corrosion in freshwater systems is unknown. Therefore, to understand the role of methanogens in corrosion under anoxic conditions in a freshwater environment, we investigated the corrosion activities of methanogens in samples collected from groundwater and rivers. We enriched microorganisms that can grow with CO2/NaHCO3 and Fe-0 as the sole carbon source and electron donor, respectively, in ground freshwater. Methanobacterium sp. TO1, which induces iron corrosion, was isolated from freshwater. Electrochemical analysis revealed that strain TO1 can uptake electrons from the cathode at lower than -0.61 V vs SHE and has a redox-active component with electrochemical potential different from those of other previously reported methanogens with extracellular electron transfer ability. This study indicated the corrosion risk by methanogens capable of taking up electrons from Fe-0 in anoxic freshwater environments and the necessity of understanding the corrosion mechanism to contribute to risk diagnosis.

Automated summary

This study identified a methanogenic isolate, Methanobacterium sp. TO1, capable of inducing iron corrosion by accepting electrons from Fe-0. Electrochemical analysis revealed that TO1 can uptake electrons at a lower potential compared to previously reported methanogens with extracellular electron transfer ability. This study highlights the corrosion risk posed by methanogens in anoxic freshwater environments and the importance of understanding the corrosion mechanism.