For more than 100 years, scientists have predicted the existence of manganese-eating bacteria. But none has been found—until now, Science News reports. Two environmental microbiologists left a jar covered in manganese carbonate, a pink metal compound, in the sink to soak. Ten weeks later, they returned to something remarkable. The jar’s contents had been replaced with a new substance, dark and crusty. And two new species of bacteria were responsible, according to a study the researchers published last week in Nature. The bacteria, tentatively christened Candidatus Manganitrophus nodulliformans and Ramlicbacter lithotrophicus, can borrow electrons from metals like manganese and use them as fuel for growth. When metals lose electrons, they oxidize; in the case of the dirty jar, this caused the contents to transform from manganese carbonate into manganese oxide (above). Because both species likely came from tap water, the findings could help control manganese oxide pollution in drinking water, the researchers say.
*Correction, 23 July, 10:45 a.m.: An earlier version of this story incorrectly implied that metal-eating bacteria were previously undiscovered.