Phytoremediation of heavy metals assisted by plant growth promoting (PGP) bacteria: A review

Continued industrialization, agricultural practices, and other anthropogenic activities lead to heavy metals contamination. Heavy metals have severe toxic effects on plants, animals, and human health, and therefore their remediation is crucial. Among the various techniques used, phytoremediation is one of the safest, most innovative, and effective tools for the remediation of heavy metals. Phytoremediation of toxic metals and metalloids has been reported by researchers using a variety of plants. The efficiency of phytoremediation can be enhanced by the assistance of plant growth promoting (PGP) bacteria. These bacteria transform metals into bioavailable and soluble forms through the action of siderophores, organic acids, biosurfactants, biomethylation, and redox processes. In addition, PGP bacteria possess growth-promoting traits, including phosphorus solubilization, nitrogen fixation, iron sequestration, and phytohormone and ACC (1-aminocyclopropane-1-carboxylic acid) deaminase synthesis, which improve plant growth and increase plant biomass, in turn assisting phytoremediation. Our current review of the literature highlights the potential of PGP bacteria, which facilitate phytoremediation of heavy metals in contaminated areas.