What is Heavy Metal Tolerance

Use of microorganisms and their enzymes to degrade heavy metal contaminants from the environment, is termed as bioremediation. This chapter majorly deals with heavy metals, their toxicity and their ill effects upon the environment. It depicts how microbes can help to combat the side effect of heavy metal toxicity by stimulating their natural defensive mechanism. In spite of their natural defensive system against metal pollution, still there is an urgent need of utilizing advanced molecular tools to further exaggerate their resistance ability for bioremediation. Earlier accumulation of heavy metals was done through overproduction of various metal binding proteins located in the cytoplasm. Recently cell surface engineering of microbes appears an attractive technology for removal or recovery of metal ions from the environment. To expedite the degradation of pollutant, a number of different molecular tools have been established for improving the microbial strains at molecular and genetic level. Microbial engineering thus, seems a promising approach which elucidates the effect of biotechnological processes used for decontaminating the polluted environment and in the future, humans and animals might gain from these organisms in remediating environmental contamination. However, these genetic modifications should be stable and harmless towards the nature as well as for the microbes itself and any genetic alterations must always ensure the actual pros and cons behind it.