Overview of Mercury Methylation Capacities among Anaerobic Bacteria Including Representatives of the Sulphate-Reducers: Implications for Environmental Studies

Abstract

Mercury methylation has been extensively reported in the literature among “Firmicutes” and “Proteobacteria.” Nevertheless, results are hardly comparable because of differences in initial inorganic mercury concentrations used. The use of stable isotopic tracers now permits to study mercury transformations at concentrations close to environmental levels. Here, several strains, including strict fermentative and sulphate-reducing bacteria, were tested for their mercury methylation capacities and the results were compared with data available to date. Under such conditions, mercury methylation only occurs among the delta-Proteobacteria. The absence of relation between taxonomic/phylogenetic affiliation and mercury methylation capacities was pointed out and discussed for environmental studies.

Keywords:

• Mercury
• methylation
• methylmercury
• sulphate-reducing-bacteria
• Geobacteraceae
• Clostridia

We acknowledge the financial support by the “Conseil Régional d'Aquitaine” and the French “Agence Nationale de la Recherche” (ANR). M. R-P. was supported by a doctoral grant from the “Conseil Général des Pyrénées Atlantiques.” R. B. was supported by the ANR within the project MINAMETA (JCJC-2006-044).