Novel Metal Accumulator and Protease Secretor Microbes from East Calcutta Wetland

Abstract

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

Accumulation of some heavy metals by metal resistant avirulent Bacillus anthracis PS2010 isolated from Egypt

“…As a result, they produce and accumulate large amounts of sulfide which transfer across the membrane into the culture medium and could be used as sulfur source in the formation of PbS nanoparticles. This property of metal particle generation enables the bacteria to work as a living factory and as an inexpensive system to produce metal nanoparticles which have a strong application in the field of material science (Chowdhury et al, 2008). The mechanism of PbS synthesis by B. anthracis PS2010 is suggested to be a precipitation of Pb by DMDS off gas produced by the cells from methionine amino acid in the form of PbS nanoparticles (Macaskie et al, 2007).…”

“…Aqueous solutions of the metal salts: CdCl 2 -2H 2 O, CuSO 4 -5H 2 O, CoCl 2, ZnSO 4 -7H 2 O and Pb(NO 3 ) 2 were prepared in de-ionized water and 0.1 mM/L were added to the nutrient agar medium. Media were sterilized, dispensed in Petri plates and then inoculated with bacteria; the plates were incubated at 35°C for 24 h. The tolerance was checked on the basis of growth observed within 24 h of cultivation according to Chowdhury et al (2008). The grown colonies were used for detection of minimal inhibitory concentrations (MICs) for each metal.…”

“…Before and after the treatment with Pb(NO 3 ) 2 , cell of isolate was examined by scanning electron microscope (SEM) to detect any change in the morphology of the cells as a result of metal treatment. The control and treated cultures were also examined by transmission electron microscopy (TEM) in order to identify the location of lead particles within the cells (Chowdhury et al, 2008). Cells of control and treated cultures (as described before) were centrifuged at 5000 rpm, washed twice and fixed in 2.5% buffered glutaraldehyde in 0.1 M PBS (phosphate buffer solution) pH: 7.4 for 24 h at 4°C, washed three times with PBS for 10 min each time and then centrifuged at 5000 rpm.…”

East Kolkata Wetland: A Multifunctional Niche of International Importance

“…This resulted in isolation of oil degrading, extracellular protease producing as well as metal accumulating microbes (Adarsh et al, 2007;Chowdhury et al, 2008). The variation in microbial population at different sites of EKW through culture independent analysis reveals the underlying bio remedial activity of this area.…”

“…Advances in information technology based data retrieval system allowed prediction of the putative functions of the different groups of microbes indicating the possible presence of metal accumulating, oil degrading, antimicrobial compound producing as well as enzyme producing bacteria which can be exploited for commercial purposes . The removal of metals from waste water during its journey through the wetland (Chattopadhyay et al, 2002) and the presence of metal accumulating microbes from EKW have been reported in a variety of studies (Adarsh et al, 2007;Chowdhury et al, 2008).…”