Recoloured SEM of Gloeomargarita lithophora with amorphous carbonate mineral phase inclusions.

A Gloeomargarita lithophora bacterium containing carbonate granules (white spheres). The microbe’s ability to form such granules internally might explain how it draws radioactive isotopes from its surroundings. Credit: Karim Benzerara and Stefan Borensztajn/CNRS

Environmental sciences

Nuclear waste? These microbes might help with the cleanup

Bacteria discovered in a Mexican lake accumulate two radioactive isotopes in their cells.

A species of photosynthetic bacterium could help to soak up radioactive contaminants in polluted waterways.

Benjamin Kocar at the Massachusetts Institute of Technology in Cambridge, Massachusetts, Karim Benzerara at the Sorbonne University in Paris and their colleagues found that the bacterium Gloeomargarita lithophora is particularly adept at sucking up the radioactive isotopes radium-226 and strontium-90. The former has a half-life of 1,600 years, can be found in mining and power-plant runoff, and is one of the most common radioisotopes in groundwater. By contrast, 90Sr mainly reaches waterways from nuclear tests and accidents, and has a half-life of 29 years. Both are thought to pose risks to the environment and human health, and prior research has explored the ability of various microbes, fungi and other organisms to gobble them up.

Compared with organisms studied previously, G. lithophora showed the highest uptake of both 90Sr and 226Ra. This ability is probably related to a process by which G. lithophora draws in substances from its environment to form internal clumps of calcium carbonate.