Biosorption of Cd by an indigenous Cd-resistant bacterium isolated from soil contaminated with Cd

An indigenous Cd-resistant bacterium, G17-2, was isolated from Cd-contaminated soil and characterized for its potential application to Cd biosorption. Phylogenetic analysis using 16S rRNA sequences revealed that G17-2 was affiliated to Pseudescherichia vulneris. When grown in yeast extract-peptone-dextrose medium, G17-2 showed the optimal growth at 30 ? and pH 7. Efficiency of Cd biosorption was investigated using live and dead G17-2 biomass at different initial Cd concentrations (25-100 mg/L), temperatures (15-40 ?), and pH (5-9). Under optimal growth conditions, the live G17-2 removed Cd with a maximum of 33.5 mg/g and showed 71.3% of Cd removal capacity. Dead cells removed 24.1 mg Cd/g with removal capacity of 35.6%. Cadmium removal capacity decreased with the initial Cd concentration increasing. Field emission scanning electron microscopy with energy dispersive spectroscopy and Fourier transform infrared spectroscopy analysis presented the changes in functional groups distribution of G17-2 surface after biosorption. G17-2 showed the highest minimum inhibitory Cd concentration of 2,250 mg/L among the other bacteria previously reported. Our results demonstrated that G17-2 strain has a high potential for bioremediation of Cd-contaminated aqueous system.