When microbiologist Jarid Ledbetter once returned to his office for the first time in months after a business trip, he found something strange.
The creamy manganese carbonate (MnCO3), which used to paint the glassware it left soaked in a basin, has turned dark. As if something had stolen some of its electrons.
Electron thieves
"The dark matter was a form of manganese oxide (Oxide Manganese) - a product that is formed when manganese ions lose electrons, and they undergo a reaction called oxidation, but there must be something," said Ledbeter, a researcher at the California Institute of Technology - Caltech. What might stimulate the reaction - the electron thief. "
"I began to wonder if the long-sought microbes might be responsible, so we conducted systematic tests to find out," Leadbetter explains.
To verify if this was actually caused by a biological process, Leadbeater and his team further encapsulated the flasks with manganese carbonate, and sterilized some of them with the burning steam.
The result, published in the journal Nature on July 15, was that the manganese compound on these sterile flasks did not change color until a year later.
But the bottles that were not sterilized acquired a dark color. Therefore, make sure that the electron thief is something that can be destroyed by hot steam, according to the Science Alert report on the study.
Two possible Janian
The researchers cultivated what was on the bottles, and the RNA analysis revealed the presence of 70 types of bacteria, but with further tests, the team was able to exclude some species, so only two potential cyclists remained.
The two culprits were: Nitrospira, which are usually crescent-shaped, and Betaproteobacterium, and relatives of these two types of bacteria are known to live in groundwater.
After that, the team "isolated the beta-YouTube bacterium on single bacterial farms, but it was found that this species does not oxidize manganese carbonate alone, either that nitrospira alone is responsible or that this was a joint action."
The team realized that electron theft might have been a team effort, but what's the motive? The researchers had their doubts.
Chemical synthesis
Researchers used carbon manganese called carbon 13 on some of their bacterial farms, and it was found enough that bacteria had incorporated carbon isotopes into their bodies, which assured them that the suspected bacteria were self-feeding, that is, able to produce their food using an energy source.
Bacteria used the energy of manganese electrons to convert carbon dioxide into usable carbon, just like plants that use sunlight to convert carbon dioxide and water into sugars and oxygen during photosynthesis.
This process is called "chemical synthesis", and although this process is known to occur using other minerals, it is the first time we have seen cells use manganese in this way.
"This is the first bacteria that has been found to use manganese as a fuel," said Leadbiter.
Water pipes and other things
While it is one of the most common elements on the surface of our planet, much about manganese and its role on Earth remains a mystery, including its bizarre tendency to block water pipes.
"There is a whole bunch of environmental engineering literature on drinking water distribution systems that are blocked by manganese oxides," Leadbetter said.
But how and why these materials were created, it remains a mystery. Many scientists have considered that bacteria that use manganese in energy may be responsible, but there has been no evidence to support this idea until now.
Manganese oxide also appears mysteriously as nodules on the sea floor, and manganese participates in many interrelated cycles of elements including carbon, nitrogen, iron, and oxygen. So, the presence of such newly discovered bacteria can explain many.
"This discovery fills a large scientific gap in our understanding of Earth's initial cycles, and adds to the diverse ways in which manganese - a mysterious transition metal - has evolved life on our planet," said Caltech geologist Woodward Fisher, who was not involved in the study.