As compared to toxic organics and inorganics, that in many cases can be degraded, the metallic species that are released into the environment tend to persist indefinitely, accumulating in living tissues throughout the food chain. Heavy metal pollution in aquatic ecosystems has become a global phenomenon because these metals are indestructible and most of them have toxic effects on each component of the ecosystem. Most of the fresh water bodies all over the world are getting contaminated thus declining their suitability. In this scenario, monitoring and assessment of such freshwater systems has become an environmental concern. In the state of Gujarat particularly Central Gujarat, South Gujarat and some parts of Western Gujarat many pharmaceuticals industries, dye manufacturing units, electroplating industries, pesticides/ insecticides manufacturing industries are situated. Effluents of these industries are constantly adding heavy metals either in the running water or are discharged in an open land which percolates down and contaminate the ground water and thus pollute the water making it unusable for drinking purpose. This effluent contaminates ground water as well as running water. Removal of heavy metals from the environment is of the immediate importance of the present time. Adsorption or accumulation of heavy metals by microorganisms has received much attention recently due to its potential use in waste treatment processes involving removal of heavy metal pollutants from a contaminated environment. Heavy metal like mercury has threatened the sustainability aquatic biodiversity as well as the quality of human life too. Mercury complexes with organic and inorganic ligands and, is easily adsorbed to surfaces of particulates owing to its high reactivity and affinity to thiol groups. In present research, the effect of thiol group containing compound (Sodium Thiosulphate and Sodium Thioglycolate) was checked on the growth of Bacteria. Some pharmaceutical effluents contain organic compounds such as Phenol, Toluene, along with heavy metals like mercury and cadmium. In the present work MRB (Mercury Resistant Bacteria) were studied for the degradation of aromatic organic compounds especially phenol and Toluene. The isolated MRB have displayed mercury tolerance upto 100 ppm concentrations. The results reveal that MRB have ability to degrade toluene and heavy metal bioremoval capacities can be enhanced by treating them with thiol compounds like sodium thioglycolate. The concentration of Sodium Thioglycolate which is most suitable for bioremoval efficiency of MRB is around 0.1 Gm/L. Heavy metal tolerant bacteria also demonstrate resistant to various traditional antibiotics too. Ecotoxicological studies on selected plant, bacterial and yeast species reveal that the effluent treated with MRB has shown decreased toxicity thereby promoting the better growth of respective species as compared to the growth in presence of untreated effluent.
