In vitro efficiency of mercury biosorption capacity by rhizospheric bacteria

Abstract

The aim of this study was to isolate rhizospheric bacteria from mercury-contaminated soils and to evaluate them in vitro tolerance to different mercury concentrations. Rhizosphere soil was collected from each site. The determination of mercury concentration in the rhizosphere was carried out by instrumental cold vapors atomic absorption spectrophotometry. Bacteria were isolated from the rhizosphere; sensitivity and tolerance to different mercury concentrations were evaluated in vitro. The average concentration of mercury in rhizosphere was 2,56 ± 5,6 mg/kg. The amount of bacteria in the rhizosphere was 1,2± 9,7 10x1010 CFU/g soil. The bacterial species with the ability to tolerate mercury were Bacillus cereus strain ML259; Bacillus mycoides O-1 and Bacillus cereus strain LB1016. The phylotype identified as Bacillus cereus showed the ability to tolerate up to 500 mg/L of HgCl2, showing an alternative for the bioadsorption of this metal in the field. Key words: Bacteria, rhizosphere mercury, tolerance.