Heavy metals toxicity to food crops and application of microorganisms in bioremediation

Abstract In recent times, industrialization and urbanization has increased alarmingly over the year that resulted an upsurge in contamination of heavy metals (HMs) in soil systems. The indiscriminate application of HMs in different industries causes the discharge of HMs in superfluous amount that ultimately causes the losses in soil fertility, microbial diversity, as well as crop productivity. Food crops (vegetables, cereals, and legumes) are one of the important dietary human food components worldwide. After their discharge, HMs reaches to soil system and taken up by plants and ultimately causes the toxicity to plants. The toxicity of HMs in plant organs can be seen in the form of cytotoxicity, oxidative stress, and DNA damage. Furthermore, when HM contaminated foods are consumed by humans, they cause severe disease symptoms and some childhood malignancies. To overcome the problem of HMs contamination, several physicochemical strategies have been applied by scientific workers in many ways. But these chemical strategies of HM removal from contaminated sites have certain limitations and most of the time causes failure. So, now a days, a group of beneficial soil bacteria often termed plant growth promoting rhizobacteria (PGPR) having biological properties of growth promotion and HM removal are being applied to clean up the HM contaminated sites. These PGPR have the unique ability of metal chelation, biosorption, metal reduction, and bioremediation. Present chapter describes about the toxicity of HM to various food crops and their biomanagement efficacy by using the soil bacteria, that is, PGPR.