Characterization of cadmium bioremediation potential of Arthrobacter sp. SC2-19

Arthrobacter sp. is ecologically beneficial microorganisms with potential for applications for remediating cadmium contamination. In this study, Arthrobacter sp. SC2-19 was isolated from polluted soil, exhibiting a minimum inhibitory concentration of 2900 mg/L for CdCl₂. Arthrobacter sp. SC2-19 showed broad environmental adaptability, growing at pH 5-9, salt ion concentrations of 0.5-5%, and temperatures of 18-38 °C. At pH 5 and a biomass concentration of 1 g/L, it adsorbed 53.23% of Cd²⁺ from a 60 mg/L solution within 60 min. In soil contaminated with 5 mg/kg cadmium, adding 0.5% (w/w) of strain SC2-19 reduced the exchangeable cadmium fraction by 25.48% and increased the residual fraction by 13.36%. The adsorption isotherm and kinetic analyses indicated that the Cd²⁺ adsorption process was heterogeneous and multilayered. Under Cd²⁺ stress, cells exhibited tip swelling and intercellular adhesion leading to branching. Key functional groups, including -OH, N-H, amido, phosphate, and sulfate, on cell surface proteins and polysaccharides were involved in Cd²⁺ binding. These findings provide a theoretical basis for understanding the molecular mechanisms of bacterial heavy metal adsorption and highlight the potential of Arthrobacter sp. SC2-19 for cadmium pollution remediation.