Nano-titanium dioxide (TiO₂)-induced changes affecting Cu²⁺-mediated alterations in bacterium Bacillus subtilis and α-amylase

Abstract

Titanium dioxide (TiO₂) nanoparticles possess the potential to coexist with Copper (Cu²⁺) in soil. The individual and combined toxicity of these two chemicals was evaluated using the bacterium Bacillus subtilis, a known soil model bacterium. Cu²⁺ (6.25–50 µg mL⁻¹) alone produced toxicity to bacteria as evidenced by the decreased cell viability and deceased α-amylase production. The addition of TiO₂ (50 mg mL⁻¹) enhanced the Cu²⁺-induced decrease in cell viability but elevated amylase activity. TiO₂ did not markedly affect the growth rate and lag period. A primary cause of TiO₂ increasing Cu²⁺ toxicity is presumed to be associated with hydroxyl radical formation, while increased amylase activity is considered to arise from Cu²⁺ facilitating TiO₂ degradation ability.

Keywords:

• nano-TiO₂
• α-amylase
• B. subtilis
• Cu²⁺

Acknowledgments

Funding for this research was provided by the project grants of National Natural Science Foundation of China (nos 40871223 and 40901148), and Science and Technology Commission of Shanghai Municipality, China (no. 0752nm025).