Phosphate-solubilizing microorganisms for sustainable remediation of heavy metal(loid)-contaminated soils: underlying mechanisms and practical implications

Soil heavy metal(loid) pollution remains one of the most critical environmental challenges worldwide, and increasing attention has been paid to remediation strategies. Phosphate-solubilizing microorganisms (PSMs) have been identified as promising bioremediation microorganisms due to their multifunctional roles in nutrient cycling and heavy metal(loid) stabilization or mobility. This review provided the remediation mechanisms of heavy metal(loid)-contaminated soils by PSMs, including surface adsorption, chelation with siderophores, organic acids, and exopolysaccharides. During the remediation process, PSMs could also enhance the soil available phosphorus which could further immobilized heavy metal(loid)s. The PSMs could also combine with hyperaccumulators and soil amendments to increase the remediation efficiency through altering the bioavailability of heavy metal(loid)s. The remediation efficiency of PSMs could be influenced by soil characteristics, environmental conditions, and heavy metal(loid) properties, which relate with the PSMs activity. The PSMs application may also result in soil acidification, disrupt the native microbial communities, and increase the mobilization of heavy metal(loid)s, which could not be ignored. This work will provide guidelines for the safe and effective remediation of metal(loid)-contaminated soils using PSMs. Future research should aim to optimize PSM application on enhancing the remediation efficiency of contaminated soils and decreasing the ecological risks.