Scientists have traced the evolutionary branches of Arctic bacterial resistance to toxic mercury — an adaptation that appears to have an ancient lineage. Up to 31 percent of bacteria retrieved during an Arctic expedition and grown in lab cultures contain the mercuric reductase gene(merA), a genetic sequence that encodes an enzyme that is capable of breaking down toxic mercury into a more harmless chemical form.

The study, detailed in the journal FEMS Microbiology Ecology, looked more closely at the diversity of merA genes among mercury-resistant bacteria in the Arctic. The research was funded in part by the Exobiology and Evolutionary Biology element of the NASA Astrobiology Program.