Nine bacterial isolates were screened from different sites of East Calcutta Wetland, an ecosystem located at the eastern fringes of Calcutta. Other than being a biodiversity rich area, the important feature of this system is that it is a natural sewage treatment plant for the city of Calcutta. In addition to daily sewage including solid and soluble wastes, a considerable load of toxic metals are released into the water bodies from industries, tanneries, agriculture, household as well as health sectors. Screening out microbes from such an environment was done keeping in mind their multi functional application. These bacterial isolates were found to produce extracellular protease which is known to have vast applications in the commercial market of enzymes. The key area of this study is exploring the role of these isolates in heavy metal remediation. These isolates were found to tolerate heavy metals like Ag, Al, Cu, Cr, Co, Ni and Pb. Energy Dispersive X Ray Fluorescence (EDXRF) analysis and Transmission Electron Microscopy of the metal treated cells confirm the intracellular accumulation. Moreover, a preliminary demonstration of the effect of metal induced stress on cell surface features was determined by Scanning Electron Microscopy

Abstract:The present paper put forth the isolation and complete characterization of three bacterial isolates from different sites of East Calcutta Wetland (ECW). These isolates show tolerance to heavy metals like Ag, Al, Cu, Cr, Co, Ni, Pb and were found to be efficient metal accumulators as evident from Energy Dispersive X Ray Fluorescence (EDXRF) analysis and Transmission Electron Microscopy (TEM). Beyond intracellular accumulation, these isolates also show metal deposition in form of particles inside the cells which can further open up the area of microbe fabricated nanoparticle generation. The heavy metal accumulation in the cell can trigger different response mechanism such as change in cell morphology which was observed by scanning electron microscopy (SEM). The metal uptake property of these isolates can be applied for the heavy metal removal and recovery from industrial effluents.