MERCURY RESISTANCE IN NITROGEN-FIXING SOIL BACTERIA

Abstract

A large number of mercury-resistant nitrogen-fixing bacteria were isolated by screening soil samples from agricultural farms of West Bengal, India. All of the samples were found to contain significant quantities of mercury. Twenty five of the pure isolates were identified to the generic level following Bergey's Manual of Determinative Bacteriology, 8th edition. These organisms were resistant to HgCl₂, and a few of them were resistant to phenylmercuric acetate (PMA) as well. Their mercury resistance was also associated with antibiotic resistance properties. Growth of two mercury-resistant N₂-fixing organisms was monitored in liquid media supplemented with HgCl₂. The mercury volatilizing capacity of four mercury-resistant bacterial strains was also determined.