Microbiology researchers at the California Institute of Technology have made a discovery that ends a 100-year search for a microbial process that can make a living from manganese. The researchers found a type of bacteria that feeds on manganese and uses metals as their source of heat. This type of microbe was predicted to exist more than 100 years ago, but they were first discovered by the California Institute of Technology.
Scientists say bacteria can also use manganese to convert carbon dioxide into biomass in a process called chemical synthesis. Prior to this discovery, the researchers knew that bacteria and fungi could oxidize manganese, but only speculated that there might be microbes that could use the process to drive growth.
The bacteria was discovered in an unrelated experiment using a light, chalk-like manganese. A researcher left a glass jar stained with the substance in the office sink to soak up water a few months before leaving for work outside the school. When he came back, the jar was covered with a black substance.
After seeing the substance, he wondered if it was caused by microbes, so he conducted experiments to decide. The black coating is the manganese oxide oxidized by the bacteria, most likely from tap water. The researchers point out that there is evidence that the creature lives in groundwater.
Scientists point out that there is a whole set of environmental engineering literature on how drinking water distribution systems are blocked by manganese oxide, but how manganese oxide is produced is a mystery. Although scientists speculate that bacteria may be the cause of the blockage, this is the first clear evidence. The researchers say the discovery fills a major gap in understanding the Earth’s elemental cycle.