Metal-eating bacteria discovered by accident

Hyperaxion Jul 20, 2020

Dr. Jared Leadbetter, a professor of microbiology, was surprised to find a new species of bacteria in objects used in an experiment with manganese carried out months ago.

In a new study by the California Institute of Technology (Caltech) in the United States, scientists have discovered a new species of bacteria that feeds on manganese and uses it as an energy source.

Metal-eating bacteria discovered by accident
Manganese oxide nodules generated by bacteria discovered by the Caltech team. The nodules are usually about 0.1 to 0.5 mm in diameter. (Credit: Hang Yu / Caltech).

The researchers believe that the species, called Candidatus Manganitrophus noduliformans, has existed for more than a century, but has gone unnoticed until now. The results of the discovery were published in the journal Nature on July 15.

The study revealed that these bacteria can use manganese to convert carbon dioxide into biomass, in a process called chemosynthesis.

Species of bacteria and fungi capable of oxidizing manganese or removing its electrons were already known to scientists, but a microorganism that used the oxidation process of manganese to feed and grow had never been found before.

The way the bacteria was discovered was also unexpected. Jared Leadbetter, professor of environmental microbiology at Caltech, accidentally found it after conducting experiments with manganese.

He had left a glass jar of the substance soaked in tap water in his office sink before leaving for several months to work off campus. When he returned, the jar was covered with a dark material.

The black coating was oxidized manganese generated by the newly discovered bacteria, which probably came from the tap water itself.

“These are the first bacteria found to use manganese as their source of fuel,” Leadbetter said. “A wonderful aspect of microbes in nature is that they can metabolize seemingly unlikely materials, like metals, yielding energy useful to the cell.”

The discovery may help researchers better understand the geochemistry of groundwater. It is already known that bacteria can break down pollutants in groundwater, in a process called bioremediation.

The research results may also help to explain the manganese nodules that have been found in much of the seabed since the 1870s, through the HMS Challenger expeditions.

In recent years, mining companies have expressed interest in exploring these nodules, as they may contain rare metals in their composition.

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