Investigation of lead(II) uptake by Bacillus thuringiensis 016

In this work, we investigated the lead(II) biosorption mechanism of Bacillus thuringiensis (Bt) 016 through batch and microscopic experiments. We found that the maximum lead(II) biosorption capacity of Bt 016 was 164.77 mg/g (dry weight). The pH value could affect the biosorption of lead(II) in a large extent. Fourier transform infrared analyses and selective passivation experiments suggested that the carboxyl, amide and phosphate functional groups of Bt 016 played an important role in lead(II) biosorption. Scanning electron microscopy observation showed that noticeable lead(II) precipitates were accumulated on bacterial surfaces. Further transmission electron microscopy thin section analysis coupled with energy dispersive X-ray spectroscopy as well as selected area electron diffraction indicated that lead(II) immobilized on the bacteria could be transformated into random-shaped crystalline lead-containing minerals eventually. This work provided a new insight into lead(II) uptake of Bt, highlighting the potential of Bt in the restoration of lead(II) contaminated repositories.