Detoxification of mercury and organomercurials by nitrogen-fixing soil bacteria.

ABSTRACT

Minimal inhibitory concentration values of HgCl2 and 5 organomercurials were determined against 24 mercury-resistant N2-fixing soil bacteria previously isolated from soil and identified in our laboratory. These bacterial strains also displayed multiple antibiotic resistant properties. Typical growth pattern of a highly mercury-resistant Beijerinckia sp (KDr2) was studied in liquid broth supplemented with toxic levels of mercury compounds. Four bacterial strains were selected for determining their ability to volatilize mercury and their Hg-volatilizing capacity was different. Cell-free extracts prepared from overnight mercury-induced cells catalyzed Hg2+-induced NADPH oxidation. Specific activities of Hg2+-reductase which is capable of catalyzing conversion of Hg2+ →Ηg (o) of 10 Hg-resistant bacterial strains are also reported.