ABSTRACT The joint remediation of heavy metal (HM) -contaminated soil using beneficial microorganisms and plants has gained increasing attention as a sustainable approach. In this study, three growth-promoting bacterial strains (JG1, 2G5, and 2G6) with strong cadmium (Cd) and lead (Pb) tolerance were isolated through multistaged screening, and the effects and underlying mechanisms of soil HM remediation were investigated. Stress-resistant growth experiments confirmed the growth viability of these strains under Cd and Pb stress. The inoculation with the tolerant bacteria enhanced the biomass (by 13. 71%–23. 25%), plant tissue metal concentrations (by 16. 07%–62. 50%), and HM accumulation (by 41. 04%–100. 63%) in Amorpha fruticosa L. grown in contaminated soil, with 2G5 demonstrating the most pronounced effect. Principal coordinate analysis indicated that HM contamination exerted a greater impact on rhizosphere soil bacterial communities than did bacterial inoculation. Among the tested strains, 2G5 induced the most significant alterations in microbial composition. Furthermore, niche shifts in key taxa (e. g. , p_ Patescibacteria and g_ Flavisolibacter) and enhanced microbial stability were identified as potential strategies for mitigating HM stress and promoting phytoextraction. Partial least squares path modeling revealed that the application of tolerance-promoting bacteria significantly reduced soil Cd risk through the regulation of soil nutrients, enzyme activity, and plant biomass, whereas Pb levels were primarily influenced by plant biomass and microbial diversity. Overall, this study provides an efficient strategy for remediating Cd- and Pb-contaminated soils through the synergistic application of specific microbial inoculants and A. fruticosa L. IMPORTANCE HM contamination poses severe threats to ecosystem safety and human health. This study demonstrates that inoculating Amorpha fruticosa L. with cadmium/lead-tolerant plant growth-promoting bacteria (PGPB) (especially strain 2G5) significantly enhances phytoremediation efficiency by increasing plant biomass and metal accumulation. More importantly, we reveal that bacterial inoculation reshapes the rhizosphere microbial community, promotes niche shifts in key taxa (e. g. , Patescibacteria and Flavisolibacter), and enhances microbial network stability, which collectively improve plant adaptability to metal stress. These findings provide a microbial-enhanced phytoremediation strategy that is sustainable and eco-friendly, offering practical insights for the remediation of HM-contaminated soils in real-world scenarios, especially in regions with leguminous vegetation.
Liu et al. (Fri,) studied this question.