Bioreduction of Iron and Biosorption of Heavy Metals (Ni 2+,Co 2+,Pb 2+ ) by a Novel Environmental Bacterium,Tabrizicola aquatica RCRI19 T

Environmental bacteria have an important role in the removal and improvement of metals from polluted area. Metal–microbe interactions as a form of detoxification of metal have been developed. In this study, we investigated the ability of Tabrizicola aquatica RCRI19^T, a novel environmental bacterium isolated from deepwater from Qurugöl Lake nearby Tabriz city, Iran, to Fe(III)-reduction as an electron acceptor in minimal essential elements condition. Subsequently, bioabsorption behaviour of heavy metals (Ni²⁺, Co²⁺, pb²⁺) by strain RCRI19^T has been demonstrated. Our results showed that strain RCRI19^T can reduce 20mM ferric-citrate particularly in anaerobic condition, and a positive correlation was observed between bacterial growth and iron (II) production. Owing to its iron reduction rate, T. aquatica RCRI19^T may contribute to iron mineral transformation and element cycling in deepwater of the lake. We further observed that the dead biomass of strain RCRI19^T absorbs of heavy metals (Ni²⁺, Co²⁺ and Pb²⁺) from aqueous solution. The optimum conditions of biosorption are in pH = 4 for Ni²⁺, Pb²⁺ and pH = 5 for Co²⁺. The equilibrium experimental data fitted both of Freundlich and Langmuir isotherms and displayed monolayer adsorption. Two kinetic models, namely pseudo-first-order and pseudo-second-order were used to describe the kinetics of heavy metal ion biosorption on T. aquatica. Pseudo second order was the best of the other kinetic.