The effects of P. aeruginosa ATCC 9027 and NTA on phytoextraction of Cd by ramie (Boehmeria nivea (L.) Gaud)

Abstract

In pot experiments, the effects of Pseudomonas aeruginosa ATCC 9027 and nitrilotriacetic acid (NTA) on Cd phytoextraction from contaminated soil by Boehmeria nivea (L.) Gaud (ramie) was investigated. Ramie was grown in a sandy soil in the presence of 30 mg kg⁻¹ Cd and 50 mg kg⁻¹ Cd, respectively. The experimental pots were amended with P. aeruginosa ATCC 9027 or NTA at different levels (5, 10 and 20 mmol kg⁻¹) weekly. The results showed that the inoculation of P. aeruginosa ATCC 9027 alleviated the Cd-induced damages, resulting in promotion of ramie growth, improvement of antioxidative enzymes activities and increase of total Cd-uptake by ramie. By contrasting 30 and 50 mg kg⁻¹ Cd treatments, the inoculation of P. aeruginosa ATCC 9027 increased accumulation in the roots ranging from 54% to 96% and 13% to 104% in 30 and 50 mg kg⁻¹ Cd soils, respectively. The average accumulation of Cd with P. aeruginosa ATCC 9027 was about 1.95-fold (30 mg kg⁻¹ Cd) and 1.54-fold (50 mg kg⁻¹ Cd) compared to the corresponding NTA treatments. When added with NTA, the accumulation of Cd in the shoots of ramie was higher than the controls, but inhibition of plant growth and related enzyme activities were observed. The experimental results demonstrated that P. aeruginosa ATCC 9027 can greatly enhance phytoremediation efficiency. Besides, the results also indicated that P. aeruginosa ATCC 9027 was more effective than NTA to improve the efficiency of ramie under cadmium stress in practical applications.