F Zakeri - Department of Genetics, Faculty of Basic Science, Tarbiat Modares University, Tehran, Iran
M Sadeghizadeh - Department of Genetics, Faculty of Basic Science, Tarbiat Modares University, Tehran, Iran
K Akbari Noghabi - National Institute of Genetic Engineering and Biotechnology (NIGEB), P.O.Box ۱۴۱۵۵-۶۳۴۳, Tehran, Iran
M.R Kardan - Nuclear Radiation Application School, Nuclear Sciences and Technology Research Institute, Tehran, Iran

There has been great concern about the health risks associated with the exposure due to the natural radioactivity present in soil and water all over the world. The level of natural radioactivity in some areas of Ramsar, a northern coastal city of Iran, is known to be among the highest levels of natural radiation in the world due to the high concentrations of 226Ra existing in the soil and hot spring waters. In order to minimize the health hazards associated with high concentrations of 226Ra, the main objective of this study was the isolation and characterization of 226Ra adsorpting indigenous bacterial strains from soils and hot-spring waters by applying molecular approaches. In this context, soil and water samples were collected from different areas with high levels of natural radioactivity in Ramsar and 226Ra activities were measured using the high purity Ge-detector. Fifteen bacteria were isolated from soil and water samples and their phylogenetic affiliations were determined based on their 16S rRNA gene analysis. The radium sorption capacities of bacterial isolates were tested by gamma spectrometry. The results showed that uptake values of a pigmented strain Serratia marcescens ZF03 isolated from the soil (with the highest radium content of 25000 Bq.Kg-1) caused 60% removal of 226Ra at a radioactivity level of 50 Bq ml-1, after 5 minutes.

Bacterial Biosorption, High Level Natural Radioactivity, Radium-226, 16S rRNA