Improving Lead Phytoremediation Using Endophytic Bacteria Isolated from the Pioneer Plant Ageratina adenophora (Spreng.) from a Mining Area
Qiqian Li, Siyu Yao, Hua Wen, Wenqi Li, Ling Jin, Xiuxiang Huang
Abstract
This study aimed to isolate and characterise endophytic bacteria from the pioneer plant Ageratina adenophora in a mining area. Seven strains of metal-resistant endophytic bacteria that belong to five genera were isolated from the roots of A. adenophora. These strains exhibited various plant growth-promoting (PGP) capabilities. Sphingomonas sp. ZYG-4, which exhibited the ability to secrete indoleacetic acid (IAA; 53.2 ± 8.3 mg·L−1), solubilize insoluble inorganic phosphates (Phosphate solubilization; 11.2 ± 2.9 mg·L−1), and regulate root ethylene levels (1-aminocyclopropane-1-carboxylic acid deaminase activity; 2.87 ± 0.19 µM α-KB·mg−1·h−1), had the highest PGP potential. Therefore, Sphingomonas sp. ZYG-4 was used in a pot experiment to study its effect on the biomass and Pb uptake of both host (Ageratina adenophora) and non-host (Dysphania ambrosioides) plants. Compared to the uninoculated control, Sphingomonas sp. ZYG-4 inoculation increased the biomass of shoots and roots by 59.4% and 144.4% for A. adenophora and by 56.2% and 57.1% for D. ambrosioides, respectively. In addition, Sphingomonas sp. ZYG-4 inoculation enhanced Pb accumulation in the shoot and root by 268.9% and 1187.3% for A. adenophora, and by 163.1% and 343.8% for D. ambrosioides, respectively, compared to plants without bacterial inoculation. Our research indicates that endophytic bacteria are promising candidates for enhancing plant growth and facilitating microbe-assisted phytoremediation in heavy metal-contaminated soil.