Microbiologists at Caltech discovered a bacteria that feeds on manganese metal

Microbiology researchers at Caltech have made a discovery that ends a 100-year long search for microbes able to live on manganese. The researchers discovered a bacteria that feeds on manganese and uses the metal as their source of calories. Microbes of this type were predicted to exist over 100 years ago, but the Caltech discovery marks the first time they've been described.The scientists note that bacteria can also use manganese to convert carbon dioxide into biomass in a process called chemosynthesis. Before this discovery, the researchers knew that bacteria and fungi could oxidize manganese but only speculated that microbes might exist that could harness the process to drive growth.

The bacteria was discovered while performing unrelated experiments using a light, chalk-like form of manganese. A researcher left a glass jar soiled with the substance to soak up water in the office sink before departing for several months for off-campus work. When he returned, the jar was coated with a dark material.

Upon seeing the material, he wondered if the hypothesized microbes could be responsible and performed tests to decide. The black coating was oxidized manganese generated by the sought-after bacteria that had likely come from tap water. The researcher noted that there is evidence the creatures live in groundwater.

The scientists pointed out that there is an entire set of environmental engineering literature about drinking water distribution systems being clogged by manganese oxides, but how those oxides are generated was a mystery. While scientists speculated that bacteria might be the cause of the clogs, this is the first definite proof of that. Researchers say that the discovery fills a major "intellectual gap" in the understanding of the Earth's elemental cycles.