Role of Acidothermophilic Autotrophs in Bioleaching of Mineral Sulphide Ores

451-464Living organisms synthesize a wide array of enzymes, which catalyze a myriad of reactions both inside and outside the cell. The acidothermophilic iron-oxidizing bacteria represent a group of obligately autotrophic chemolithotrophs, They include mesophilic Thiobacillus thiooxidans, Leptospirillum ferrooxidans and thermophilic bacteria such as Sulfolobus and Acidianus species. Several studies have shown the importance and feasibility of microbiological prospecting for sulphide ore deposits. Acidothermophilic autotrophic bacteria are now considered as an ideal source to exploit more unusual commercial applications of Geo-biotechnology, especially for metal and mining industry. The mining of copper, uranium, molybdenum, zinc, silver, gold, etc, from their sulphide ores is successfully possible with these microbes. The predominant characteristic of chemolithotrophs is their ability to survive and flourish in a completely inorganic aqueous environment with a supply of oxidizable substrate and CO2, A number of different species have now been isolated from high temperature regions and their potential for the rapid leaching of some ores. The ability of such isolates to tolerate high concentration of toxic heavy metals makes them excellent tools for accumulation and/or for biochemical transformation of metals. The outline of such applications are described in the present review

Umrania, Bioremediation of toxic heavy metals using acidothermophilic autotrophes

Abstract Investigations were carried out to isolate microbial strains from soil, mud and water samples from metallurgically polluted environment for bioremediation of toxic heavy metals. As a result of primary and secondary screening various 72 acidothermophilic autotrophic microbes were isolated and adapted for metal tolerance and biosorption potentiality. The multi-metal tolerance was developed with higher gradient of concentrations of Ag, As, Bi, Cd, Cr, Co, Cu, Hg, Li, Mo, Pb, Sn and Zn. The isolates were checked for their biosolubilization ability with copper containing metal sulfide ores. In case of chalcopyrite 85.82% and in covellite as high as 97.5% copper solubilization occurred in presence of 10 À3 M multi-heavy metals on fifth day at 55°C and pH 2.5. Chemical analyses were carried out by inductively coupled plasma spectroscopy (ICP) for metal absorption. The selected highly potential isolate (ATh-14) showed maximum adsorption of Ag 73%, followed by Pb 35%, Zn 34%, As 19%, Ni 15% and Cr 9% in chalcopyrite

GREEN SYNTHESIS OF SILVER NANO PARTICLES

The research was carried out to investigate the synthesis of silver nano particles. The silver nano particles have wide tremendous application in the therapeutics, antimicrobials, diagnostics, catalysis, micro-electronics and high sensitivity biomolecular detection. Silver nano particles grow in a single-step method, at room temperature, and with no addition of external energy. The silver nanoparticles were synthesized from silver nitrate aqueous solution through a simple, ecofriendly and cost effective course using the leaf broth of the Oscimum sanctum, Azadirachta indica and Lawsonia Inermis (kadvi mehndi), therefore calling it green synthesis. The Synthesized AgNP was confirmed by sampling the aqueous component at different time intervals and the absorption maxima was scanned by UV-Vis spectrometry and Particle Size Distribution (PSD). Based on PSD, the particles were further characterized by Scanning Electron Microscope. Synthesized AgNP was confirmed at 531,540and 543 nm. Among the total percentage of size distribution, D-50 value, which is 50% size distribution, was taken into consideration, where the size of the nanoparticle was established to 0.135µm. Further research is going on with reference to the synthesized nanoparticles