Plant growth-promoting rhizobacteria: key role players for sustainable agriculture in heavy metal-polluted environments

Heavy metal (HM) pollution, a major environmental problem, has become a significant concern due to its persistent adverse effects on ecosystems. Chemical fertilizers and polluted water applications during agricultural practices, deforestation, and industrial waste are significant contributors to HM pollution, affecting soil fertility due to increased toxic effects on the rhizosphere microbial community, leading to reduced crop yield. Finding suitable practices to protect soil quality by alleviating HM toxicity is required for long-term sustainability. However, bioremediation is considered an effective technique to detoxify the damaging effects of HMs. Bioremediation using HM-resistant plant growth-promoting rhizobacteria (PGPRs) is effective in promoting soil fertility, leading to enhanced plant growth via increased plant growth-promoting hormones and siderophores. These PGPRs colonize the rhizosphere and promote their growth. The current review aims to present the toxic effects of different HMs on soil and their effects on plant growth reduction, which can be restored by using PGPRs as an effective bioremediation strategy to detoxify the HMs for long-term soil sustainability. The implementation of this approach is effective in improving soil fertility by mitigating HM accumulation.