With industrial progress environmental pollution due to toxic heavy metals is widely spreading. Some of the metals that are most widespread and common contaminants of the environment are copper, nickel, chromium and cadmium. These metals are trace elements that are required in small amount in the body. They act as co-factor of some important enzymes which catalyze many biological reactions. But high levels of these metals in body are extremely toxic because of the inhibition of biological reactions.


Different industrial processes are resulting in release of heave metals in the environment such as smelting, alloy manufacturing, electroplating, chemical fertilizers, deposition of metallurgical as well as petrochemical industries, land applications of sewage sludge, wood pulping, paint industry, tobacco industry,refining industry and nickel cadmium batteries.


Due to the damaging and toxic effects of heavy metals on health and human life their accumulation in environment is becoming one of the major concerns. Heavy metals are harmful because they have abilities like stability and toxicity. All the current data confirms that harmful heavy metals are widespread throughout the world and they should be blacklist to be monitored for their damaging effects in environment.


Indusial wastes when mixed with water our natural water sources become polluted that is a major threat to aquatic life of these water sources. These heavy metals contaminated water can even proved to be harmful and fatal for plants, animals including humans. When plant uptake this water it affects both their roots as well as shoots. They tend to enter agricultural crops resulting in making them toxic. When such contaminated crops are consumed by humans and animals they cause many serious problems in them like metabolic problems, embryo toxicity, mutagenesis, osteomalacia, fractures, hyperglycemia, carcinogenic diseases, vertebral osteoporosis, liver damage, aging, neuronal toxicity, immune-potency reduction and also cause damage to reproductive system.


Some heavy metals such as cadmium are involved in the activation of oncogenes, leading to damage in DNA that ultimately results in cancer. There are many evidences that heavy metals when injected are inhaled by human they cause testis, prostate cancer and in female they cause breast cancer.


By the increased awareness about heavy metals toxicity, there are various techniques being employed to remove them or to make them somewhat less toxic. The conventional methods that are used for this purpose are chemical precipitation, phytoremediation, oxidation, reverse osmosis, membrane technology, electrochemical treatment, phytoremediation, ion exchange, reduction and oxidation. But because of environmental restrains and no product guarantee the use of these approaches are very limited. Some of these techniques are very expensive like ion exchange.


Therefore there is an urgent need to find out a new technique that should low cost and eco-friendly. Studied have revealed that different microorganisms such as bacteria, algae and fungi can be used to remove heavy metals from contaminated water. Microorganisms can respond to heavy metals present in waste water by several processes like biosorption to cells walls, comlexation, transport across membranes of cells, precipitation, entrapment in ectracellular capsules and oxidation and reduction reactions.


In recent years bioremediation of heavy metals by using different microorganisms has received a great deal attention and not only on experimental level but also its industrial level applications. This field of bioremediation by using microorganisms mainly focused on environmental friendly and simpler techniques, and also helps in eliminating chemical techniques usage to remove heavy metals from waste water.


There are many processes such as bioremediation which microbes use to remove heavy metals from contaminated water like enzymatic detoxification, metal ion sequestration, active efflux of metals, removal of metalions by complexation as well as exopolysaccharides, binding to bacterial cell wall and in some cases to cell envelopes, cell surface adsorption, transformation of proteins and volatile compounds to trap heavy metals.


Therefore it is a need of the day to isolate those bacterial species that have high tendencies to heavy metals from waste water. As Pakistan is one of the developing countries with 180,00,000 people with low educational rate and unawareness about common health issues. The rate of heavy metals accumulation is very high due to non-implementation of standard international methods todiscard waste water there that then become part of agricultural plants animal and finally human body by passing along the food chains.


Another reason of environmental pollution caused by heavy metal accumulation is economic crisis that results in depletion of means and resourceswhich are used to make the environment clean and healthy. It is very important to free the environment from contamination of heavy metals like nickel, cadmium and copper, etc. by using some cheap and affordable processessuch as bioremediation by using bacterial strains. There are many research studies undergoing toidentify and isolateheavy metal resistant bacterial strains that could be optimized in future to removeheavy metals from industrial effluents in the most eco-friendly and environmental-healthy way possible.

By Web Team

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