Serratia sp. ZF03: An efficient radium biosorbent isolated from hot-spring waters in high background radiation areas

The aim of this study is to isolate and characterize 226Ra biosorbing indigenous bacterial strains from soils and hot-springs containing high concentrations of 226Ra by using biochemical and molecular approaches. Fifteen bacteria were isolated and their phylogenetic affiliations were determined based on their 16S rRNA gene and the two most relevant hypervariable regions of this gene; V3 and V6 analysis. A pigmented Serratia sp. ZF03 strain isolated from the water with 226Ra content of 50471 mBq l−1, caused 70% removal of 226Ra at a radioactivity level of 50 Bq ml−1, after 5 min and 75–80% in equilibrium time of 1 h, depending on the particular biosorption system and experimental conditions studied. The biosorption equilibrium was described by Langmuir and Freundlich isotherm models. Kinetic studies indicated that the biosorption follows pseudo-second-order kinetics. Effect of different physico-chemical parameters on 226Ra sorption, FTIR, SEM and TEM analysis were also investigated.