Microbial treatment of Pb(II) using a newly isolated Pb(II)-resistant Methylobacterium sp. MTS1 strain

Growing concerns about the adverse effects of Pb(II) on public health have drawn much attention to the development of efficient and environmentally friendly treatment methods. Here we report the isolation of a novel Pb(II)-resistant Methylobacterium sp. MTS1 strain from abandoned mine soil that has potential as a biosorbent for the removal of Pb(II). The isolated MTS1 strain not only showed high resistance even at 1,000 mg/L, but also showed excellent performance in removing Pb(II) through biosorption. The maximum removal capacity and removal efficiency of Pb(II) were found to be 56.55±6.2 mg/g and 98.6±0.6%, respectively, under optimized conditions (pH 7; biomass, 1 g/L; contact time, 60 min). Hydroxyl, amide, carboxyl, phosphate, nitro compound, and disulfide groups as well as various functional groups such as C, O, and P were identified as key factors for Pb(II) removal. In addition, equilibrium data obtained by biosorption and adsorption kinetic model were in agreement with Langmuir isotherm and pseudo-second-order models, indicating that the biosorption process involved monolayer chemisorption at uniformly distributed active sites on the surface of the MTS1 strain.