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When the microbiologist, Jared w. Leadbeater he returned to his office for the first time in months after a work trip, found something quite strange: a compound of carbonate of manganese to a cream color ( MnCO3 ) covered the crystal objects that habúa left in the sink. But, in addition, had a strange hue more dark.

I Thought, ‘What is that? “‘, says Leadbeater, a researcher at the California Institute of Technology (Caltech), who quickly realized that the carbonate magnaneso he had “stolen” their electrons. That is to say, had rusted becoming a manganese oxide . But something had to be starting the reaction: a “thief” of electrons . “I began to wonder if a few microbes sought after for decades by science could be responsible for what I set out to do tests to solve the riddle,” says the micriobiólogo for Sciencealert.

The first experiments

Leadbeater and his team covered more jars with MnCO3 and neutered, some with steam (because it is known that the MnCO3 is stable in these conditions). But the compound manganese not darkened (even a year later). Therefore, the “thief” had to be something that will be destroyed with hot steam. It is for this reason that the researchers studied what was in the jars through the analysis of RNA , which revealed that there were up to 70 bacteria . After more testing, the team ruled out the most until you are left with two possible culprits.

In particular, were bacteria Nitrospirae , that generally have the shape of a half moon, and Betaproteobacterium, in the shape of a cane. It is known that the family of both species of bacteria live in groundwater. “We isolate betaproteobacterium of the oxides are altered as single colonies… but this species does not oxidize MnCO3 only. Or Nitropirae is the only responsible for the oxidation of Mn (II) or the activity is in consortium”, type on the computer in the study just published in the journal “Nature”.

Eating metals

To check if the theft had been a team work , the researchers used manganese labelled with carbon-13 in some of their crops and, indeed, the bacteria incorporated these isotopes of carbon into their bodies. This confirmed that the bacteria suspected were autotrophic : they can produce their own food using a source of energy and, in this case, the bacteria were using the energy of the electrons of manganese to convert the CO2 into carbon usable , as plants use sunlight to convert CO2 and water into sugars and oxygen during photosynthesis.

This process is called chemosynthesis, and although it is known to occur using other metals, it is the first time that it is observed that these bacteria can use manganese as a source of fuel. While it is one of the most common elements on the surface of our planet, largely on the manganese and its cycle on Earth remain a mystery, including his strange tendency to clog the water pipes.

What clogs the pipes

“There is a complete set of literature of environmental engineering systems of distribution of drinking water that is clogged with oxides of manganese,” says Leadbetter-, but how and why it generates such material has continued to be an enigma . Many scientists have found bacteria that use manganese as energy could be responsible, but the evidence that supports this idea was not available. Up to now”.

The oxide of manganese also appears cryptically as nodes in a large part of the seafloor, and is involved in many cycles of interconnected elements that include carbon, nitrogen, iron and oxygen . It is for this reason that the “thieves” that steal electrons from manganese, as these bacteria newly discovered, could explain a lot.

The researchers say that the cell doubling times of the bacteria and the rates of oxidation would form manganese oxides in amounts equivalent to the global reserves in just two years. The close relatives of these species appear to be present in many places, and their potential to circulate this metal by the Earth could be huge.