Ground water microbes living outside a contaminated area contain mobile genetic elements that provide them resistance to heavy metals.
Bacteria and other microbes contain mobile genetic elements called plasmids that are circular DNA molecules. Plasmids often encode traits that confer some advantage to the harboring microbe such as antibiotic resistance. A team of researchers has developed a method to purify and study plasmids from ground water microbial communities. Using this method, they discovered several hundred different plasmids in samples from a Department of Energy site in Tennessee. The most common trait encoded in those plasmids was resistance to toxic metals such as mercury. The team also found that the plasmids were diverse but not as much as the microbial community they came from.