Screening and characterization of mercury-resistant nitrogen fixing bacteria and their use as biofertilizers and for mercury bioremediation

In the current study,mercury-resistant nitrogen fixing bacterial (nfb) strains were isolated by growing them on selective medium (nfm) to be used as biofertilizers and for the bioremediation of mercury from polluted soils and waters. bacterial strains isolated from the soil around root nodules were checked for resistance to mercury by growing on yeast extract mannitol (yem) medium supplemented with different concentrations of hgcl2. mercury resistant bacterial strains were primarily screened by well plate method. mercury resistant nfb strains were further checked for their h2s production by growing on lead acetate (la) medium. selected nitrogen fixing and mercury resistant bacterial strains were characterized using different biochemical tests and found to belong to genera pseudomonas,cronobacter and bacillus. quantification of detoxified mercury by selected bacterial strains was done by using dithizone method. cronobacter species were found to be significantly the most efficient in the detoxification of mercury that reached up to 95% (p<0.05). copyright 2015 zoological society of pakistan.