Phytoremediation of heavy metal contaminated soils by plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi

Abstract:

Phytoremediation, as promising remediation technology of heavy metal contaminated soils, could be more effective when assisted by microbes. Plant growth-promoting rhizobacteria (PGPR) can promote plant growth and improve plant tolerance to heavy metals through different mechanisms, such as indole-3-acetic acid (IAA) secretion, siderophore production, nitrogen fixation or phosphorus dissolution. Arbuscular mycorrhizal fungus (AMF), as important functional microorganisms in the soil-plant system, can regulate root morphology and mineral nutrition condition by infection of plant roots, adsorb heavy metals by mycelium, and change heavy metals bioavailability by production of secondary metabolites, such as glomalin, organic acid and auxin. PGPR and AMF can have beneficial synergetic effect on plant growth and heavy metal sequestration, which offers a potential for the phytoremediation of heavy metal contaminated soils. To date, many studies have been conducted worldwide about the interaction between AMF and PGPR, but the mechanisms involved are still poorly understood. In this paper, the mechanisms driven by PGPR and AMF, representing a potential for the phytoremediation of heavy metal contaminated soils, were extensively reviewed and recommendations for future investigations were made.