Identification and characterization of uranium accumulation potential of a uranium mine isolated Pseudomonas strain

Uranium accumulation by a Pseudomonas strain was characterized in terms of kinetics, effect on cell viability and role of various regulatory factors (viz. pH, Co ions and metabolism). This strain was identified as Pseudomonas aeruginosa based on 16S rRNA gene and Fatty Acid Methyl Ester (FAME) analyses. The bacterium exhibited rapid, concentration and pH dependent, uranium accumulation with maximum loading of 275 mg uranium g(-1) dry wt. at pH 4.0. Survival studies during the period of uranium exposure indicated a viable but non growing state of the cells. Uranium accumulation remains largely insensitive to metabolic activity and presence of other co-ions except Fe3+. Transmission electron microscopy (TEM) confirmed the deposition of bioaccumulated uranium by live cells within the cell envelope region. Our findings suggest that the P. aeruginosa J007 has intrinsic uranium-removal and -resistance properties. Accumulated uranium is deposited within the cell envelope region providing a possible survival strategy to the bacterium. Our study contributed significantly to gain insight into bacterial interaction with uranium and will be useful in understanding the role of native microorganisms inhabiting in uranium contaminated sites in biogeochemical cycling of uranium and in bioremediation applications.