Novel microbial consortium for laboratory scale lead removal from city effluent

Abstract

In an earlier study, we had reported the isolation and characterization of eleven bacterial isolates from different sites of East Calcutta Wetland, the natural waste recycling site for the city of Calcutta, India. It receives high concentration of toxic heavy metals daily from different industries, tanneries, agricultural as well as health sectors along with domestic sewage. Considering the fact that bioremedial activity at East Calcutta Wetland depends to a large extent on the microbial activity, attempt was made to develop a metal removal package for treatment of waste water using bacterial consortium obtained from the above mentioned site. The nature of the extracellular proteases produced by the strains was analyzed using different extracellular protease specific primers during PCR. Energy Dispersive X-Ray Fluorescence (EDXRF) analysis showed variation in metal accumulation both within and among the strains. Transmission Electron Microscopy of the metal treated cells showed presence of nanoparticles within the cells. Scanning Electron Micrographs showed distinct cytoskeleton changes of the cell in presence of metals. Bioremedial package was developed under immobilized condition both with pure isolates as well as mixed consortia for treating heavy metal containing waste water. Efficiency of Lead removal was measured using atomic absorption spectroscopy. All the isolates were found to accumulate metals to different extent. Laboratory scale bioremediation study indicated effective lead removal by immobilized consortium as well as individual strains. The mixed consortium removed 83.68% metal from distilled water and 94.4% from Bheri water both supplemented with 5 mM lead nitrate salt, within 48 h. © 2011 Asian Network for Scientific Information.