Microbes thrive on iron in oxygen-free environments

Microbes thrive on iron in oxygen-free environments
by Robert Schreiber
Berlin, Germany (SPX) Oct 27, 2024
Pipelines, sprinklers, and other infrastructure in oxygen-free settings are at risk from Microbially Induced Corrosion (MIC). This process, caused by microorganisms, leads to the degradation of iron-based structures, posing significant risks of costly damages or even infrastructure collapse. MIC is a distinct type of corrosion that occurs in the absence of oxygen, unlike rust, which is driven by oxygen-based chemical reactions. The microbes responsible for MIC feed directly on the iron, triggering a destructive reaction that damages the material. This form of corrosion is a costly issue, especially for industries like oil and gas, which lose billions of dollars annually. Addressing the microbial activity behind this corrosion is, therefore, critical.

Microbiologists PhD Satoshi Kawaichi and Professor Dr. Amelia-Elena Rotaru from the University of Southern Denmark have made important discoveries about how the microbial species "Methanococcus maripaludis" corrodes iron with high efficiency. The research, funded by a Sapere Aude grant awarded to Rotaru by the Danish Independent Research Fund, was published in "npj Biofilms and Microbiomes".

Contrary to previous assumptions, which suggested that microbes release enzymes into their environment to corrode iron and facilitate growth, this study reveals that these microbes adhere directly to iron surfaces. The microbes use sticky enzymes on their cell walls to extract nutrients without expending energy by releasing enzymes into their surroundings, which may not always reach the iron surface.

Once attached, these microbes initiate corrosion, rapidly forming a black film on the material.

"The microbes will quickly create pits under this black film, and within a few months, significant damage will occur. I would say that 5-gram iron granules visible with the naked eye are bio-deteriorated to a black powder in a month or two," said Satoshi Kawaichi.

Additionally, microbial adaptation to iron poses environmental concerns. According to the researchers, "Methanococcus maripaludis" has adapted to thrive in human-made environments by efficiently deriving energy from iron structures.

"These microbes are methanogenic, meaning they produce methane. Methane is a potent greenhouse gas, so it does cause some concern that microbes adapting to human-made, built environments produce methane more effectively. These new adaptations may spur increases in methane emissions," said Amelia-Elena Rotaru.

Methane-producing microbes also thrive on various mineral particles released into the environment through human activities like industry, agriculture, and climate change. These particles, sourced from river runoffs, forest fires, melting glaciers, and more, may encourage the growth of methane-producing microbes. Rotaru's research group is currently studying particles from melting glaciers in Greenland to assess their influence on methane emissions into the atmosphere.

Research Report:Adaptation of a methanogen to Fe0 corrosion via direct contact