Mercury transformations by heterotrophic bacteria isolated from cinnabar and other metal sulfide deposits in Italy

Abstract
Several mercury‐resistant bacteria were isolated from sites in Italy that surrounded natural mercury deposits. Bacterial strains resistant to 5 mg mercuric chloride per liter reduced Hg2+ to elemental mercury by an inducible process. One bacterial strain was resistant to methylmercuric chloride and produced elemental mercury when incubated with several organomercurial compounds. No methylmercury was detected in bacterial cultures growing in the presence of 2 mg mercuric chloride per liter. Mercury reduction is the major mercury transformation in mercury‐resistant bacteria isolated from these environments.