ABSTRACT
The term heavy metal (HM) is generally used for those metals and metalloids that have 4 g/cm3 or more atomic density. Industrial effluents are the main source of HMs and their accumulation in soil. Human activities such as mining, metallurgical processes, disposal of metals, and transportation problems play a major role in HM pollution. HMs have caused great ecological concerns due to their toxicity, which is why they are considered serious soil pollutants, as they induce severe effects on plant health. Bioremediation is a technology that relies on living organisms to deteriorate or degenerate pollutants into their lowest hazardous form. Microbes in metal-contaminated soils have been analyzed with special reference to their structure and population in the rhizosphere. In HM-contaminated soil, plant growth-promoting bacteria can help to improve the growth of a plant by direct as well as indirect mechanisms. Plant growth-promoting rhizobacteria have a strong potential to improve plant growth in various abiotic stresses such as salt, drought, and HM stress.
