Study investigates steel-eating microbes on ship hulls

Until now, researchers thought the microbial strain Mariprofundus sp. DIS-1 only thrived under anaerobic, or micro aerobic, conditions. But new research proves the steel-eating bacteria can tolerate oxygen.

The findings, detailed in the journal Applied and Environmental Microbiology, suggest steel ships and marine infrastructure are more vulnerable to corrosion than previously thought.

Mariprofundus sp. DIS-1 gains energy by oxidizing iron. Its metabolic processes trigger the formation of iron oxides, or rust.

Researchers believed the ocean-dwelling steel-eater had an aversion to oxygen. That turned out not to be the case.

"We followed up this initial finding by obtaining the genome sequence of strain DIS-1, and found that it possessed a suite of oxygen tolerance genes that are not found in other members of the Mariprofundus genus," study author Adam C. Mumford, a researcher with the U.S. Geological Survey, explained in a news release.

Previously, scientists had only studied DIS-1 in jars in the lab. To get a better idea of how the microbes are able to colonize a ship's steel hull, researchers built a system of flowing water to mimic a marine environment.

Prior studies have singled out sulfate-reducing bacteria as the culprit of microbial corrosion in marine environments, but the latest experiments prove iron-oxidizing bacteria are the first to colonize.

"We wanted to figure out how the initial colonization by iron oxidizing bacteria proceeded, and that question really drove the research," said Mumford.

By better understanding how marine microbes colonize steel, researchers hope to develop improved anti-corrosion methods for the protection of ships, pipes, bridges and other types of marine infrastructure. Underwater corrosion is a billion-dollar problem.

"Understanding the basic microbiology of this process is a crucial part of figuring out how to mitigate it," concluded Mumford.