Exogenous Pseudomonas aeruginosa application improved the phytoremediation efficiency of Lolium multiflorum Lam on Cu–Cd co-contaminated soil

Pot experiments were conducted to explore the effect of Pseudomonas aeruginosa on the phytoremediation efficiency of ryegrass on jointly Cu- and Cd-contaminated soil. P. aeruginosa application promoted the growth of ryegrass, increased the concentration of Cu and Cd in ryegrass, and enhanced the translocation of Cu and Cd from roots to shoots. The biomass of ryegrass in the T7 treatment increased by 43.1% compared to the T1 treatment. Additionally, P. aeruginosa application improved the bioavailability of Cu and Cd. The concentration of Cu and Cd in ryegrass under the T7 treatment was 48.7% and 32.8% higher than that under the T1 treatment, and the removal efficiencies of Cu and Cd from soil under the T7 treatment reached 89.5% and 89.3%, respectively. The subcellular distribution of Cu and Cd in ryegrass indicated that Cu and Cd were mainly distributed in the cell wall and cell-soluble fraction, and a large amount of Cd entered the shoot cell membrane and organelle-containing fraction under 500 mg⋅kg−1 P. aeruginosa culture application. Thus, application of 500 mg⋅kg−1P. aeruginosa culture to soil can enhance Cu uptake by ryegrass, and the maximum capacity of ryegrass to absorb Cd from the soil was reached with 50 mg⋅kg−1P. aeruginosa culture application. In light of the above results, P. aeruginosa culture application facilitated the phytoremediation of Cu–Cd co-contaminated soil by ryegrass.