
Globally, heavy metal pollution is a major issue which has seriously threatened the sustainability of environment. The toxic heavy metals emerging from sources like, industries, tannery, sewage wastes and other metal discharging industries have been found to adversely affect the density, diversity and physiological activities of soil microbiota (Xie et al. 2016). Among various heavy metals, cadmium, a highly lethal metal is widely used in batteries, for coating, electroplating, PVC stabilizers and as a component in alloy formation in various industries (Sharma et al. 2015). Due to lack of regulatory policy for controlled and safe discharge, cadmium is added to the environment via many anthropogenic activities like combustion of metal ores, burning of wastes and by the use of fossil fuels. However, after it accumulates in soils, Cd can be absorbed by plants leading eventually to the disruption of food chain and indirectly affects human health (Rahimzadeh et al. 2017). Chromium is yet another toxic metal which is used in plating, alloy formation, tanning of animal hides, for inhibiting water corrosion, textile dyes and mordants, pigments, ceramics, refractory bricks, pressure-treated lumber etc. The overuse and abuse of Cr has however hugely dented human health by acting as carcinogenic and mutagenic element (Oliveira 2012). Nickel which is even though present in very low concentrations in the environment has been found to cause serious human health problems when present beyond threshold concentrations. For instance, Ni can cause- (i) genotoxicity (ii) several types of carcinomas (iii) toxic impacts on the immune system and (iv) damage to other metabolically active tissues (Das et al. 2018).
