Effects of Herbaspirillum Sp. P5–19 Assisted With Alien Soil Improvement on the Phytoremediation of Copper Tailings by Vetiveria Zizanioides

Abstract

This study investigated examined the potential of Herbaspirillum sp. p5-19 (p5-19) assisted with alien soil improvement on improving stress tolerance and enhancing the accumulation of Mn, Cu, Zn and Cd by vetiver grass (Vetiveria zizanioides). Phytoremediation potential was evaluated by plant biomass and the ability of plant to absorb and transfer heavy metals. Results showed that the biomass was increased by 19.64%–173.81% in p5-19 inoculation treatments with and without alien soil improvement compared with control. Meanwhile, photosynthetic pigment contents were enhanced in co-inoculation treatment (p5-19 with alien soil improvement). In addition, the malondialdehyde (MDA) content was decreased, and the activities of antioxidant enzymes such as ascorbate peroxidase (APX), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were increased in p5-19 treatment, thereby alleviating the oxidative stress. Moreover, co-inoculation significantly (p<0.05) increased the concentrations of Mn, Cu, Zn and Cd in the roots and shoots of vetiver grass. In particular, the highest concentration of Mn, Zn and Cd in the shoots (roots) were obtained in C10 under p5-19 inoculation (C10B), which were 4.44– (2.71–), 4.73– (3.87–) and 5.93– (4.35–) fold as that of the controls, respectively. These results provided basis for the change of phytoremediation ability of vetiver grass after inoculation. We concluded that p5-19 assisted with alien soil improvement was a potential strategy for enhancing phytoremediation ability in tailings.