Role of Acidothermophilic Autotrophs in Bioleaching of Mineral Sulphide Ores

Abstract

Living 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 <i>Thiobacillus thiooxidans, Leptospirillum ferrooxidans </i>and thermophilic bacteria such as <i>Sulfolobus </i>and <i>Acidianus </i>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.