Microbe-Mediated Reclamation of Contaminated Soils: Current Status and Future Perspectives

Abstract

Soils contaminated with salts, metal ions, and industrial pollutants pose drastic effects on plant growth. Different physical, chemical, and biological methods are being used for improving the health of such soils to make the agricultural practices more profitable. Recently, microbe-mediated reclamation of polluted soils is attracting the researchers, farmers, and other stakeholders due to unique advantages it has as compared to chemical approaches. Characterization of potential microbes having inherent capability to tolerate salts and metals and their application as soil reclamating agents not only result in improved soil health but also ensure the higher crop productivity. In contaminated soils, these microbes facilitate plant growth through nutrient mobilization, exopolysaccharide synthesis, phytohormone production, 1-aminocyclopropane-1-carboxylate deaminase activity, and siderophore production through their bioremediation potential. Moreover, salt- and metal-tolerant microbes confer resistance to plant against deleterious effects of salinity, metals, and other contaminants present in soils. This chapter encompasses a comprehensive review of inherent potential of microbial formulations for the reclamation of contaminated soils. Moreover, the mechanisms responsible for the uptake, chelation, transformation, immobilization, volatilization, translocation, precipitation, and solubilization of heavy metals and salts are presented in detail. This chapter also covers the microbe-mediated stress alleviation mechanisms in plants by activating the antioxidant, lowering the reactive oxygen species levels, minimizing ethylene concentration, and triggering some stress responsive genes.