A bacterial methylmercury-mineralizing activity in river sediments

A bacterial activity involving mineralization of methylmercury was found in bottom sediments of the river Sambre (Belgium), in a zone highly polluted with inorganic mercury. The possibility, shown by other authors and ourselves, that biological production of toxic methylmercury compounds occurs in such a medium gives a great ecological significance to this finding.Some properties of this mineralizing activity were studied at the community level in the laboratory.The mineralizing capacity of the community can be increased in response to increased concentrations of methylmercury, probably by means of the selection of methylmercury-resistant bacterial species, among which the organisms responsible for the transformation constitute only a part.Because of this adaptation, it is suggested that some equilibrium can be reached between the degradation of methylmercury and its addition to, or its production in, mineral mercury polluted environments.