Microbe-Assisted Phytoremediation in Reinstating Heavy Metal-Contaminated Sites: Concepts, Mechanisms, Challenges, and Future Perspectives

Abstract

Pollution has become a serious matter of environmental and political concerns in the world. Our natural environment has been contaminated by various organic and inorganic contaminants, which are being used in many industrial processes and released along with industrial effluents. Among them, heavy metals are highly toxic pollutants, which cause serious environmental pollution and severe health hazards in living beings, and there is a public outcry to ensure the safest and healthiest environment for living beings. Phytoremediation, a type of bioremediation, has been emerged as an eco-sustainable technology that uses plants and their associated microbes to clean up heavy metal-contaminated soils, water, and wastewaters as compared to various physicochemical remediation technologies currently being applied for environmental restoration. However, in current scenario, phytoremediation assisted by plant-associated microorganisms, i.e., microbe-assisted phytoremediation (use of microbes, i.e., plant growth-promoting rhizobacteria, endophytes, and arbuscular mycorrhizal fungi, in assisted phytoremediation), is highly preferred for the remediation of heavy metal-contaminated sites as they have potential to alleviate the heavy metal toxicity in plants through their own metal resistance system and facilitate and improve the growth of host plants under heavy metal stress. In this line, this chapter aims to provide an overview on microbe-assisted phytoremediation, illustrate various mechanisms elicited for plant growth promotion and heavy metal phytoremediation (accumulation/detoxification), and discuss drawbacks and future challenges.