Unveiling the role of PGPRs (Plant Growth-Promoting Rhizobacteria) in phytoremediation of chemical pollutants and heavy metals

Human activities have led to the introduction of several pollutants like heavy metals and organic compounds in the environment. These contaminants find their way into the soil and water, impacting nutrient cycling and overall ecological resilience. Phytoremediation has evolved as a sustainable strategy for remediation of contaminated soils. Integration of chemical and microbial amendments is crucial to increase the efficacy of the process. Microbe-mediated processes are more suited as compared to chemical amendments like ethylenediamine tetraacetic acid (EDTA) due to the phytotoxic properties of these chemicals on beneficial soil microbes. The chapter delves into the origins of chemical and heavy metal pollutants, explores various phytoremediation mechanisms, and investigates the role of bacteria and plant growth-promoting rhizobacteria in enhancing phytoremediation. The interactions among soil components, microorganisms, pollutants, and plants are highly crucial for refining the efficacy of phytoremediation techniques. Microbes have been found to increase the bioavailability of specific elements for plant uptake, the process especially critical in the context of phytoextraction. Further, microorganisms contribute by producing various compounds, such as organic acids and siderophores which further increase the availability of metals. The chapter explores these molecular and biochemical mechanisms underlying rhizobacterial-associated processes and their impact on key phytoremediation processes, including detoxification, mobilization, immobilization, translocation, chelation, precipitation, and complexation. It has been found that the fusion of phytoremediation with bacterial interventions represents a promising solution for addressing the contamination of the soil ecosystem. Through continued research and application of the microbe-assisted phytoremediation process, restoration of contaminated sites may be achieved at a larger scale along with maintaining soil health.