ABSTRACT
Microorganisms have been involved in the natural transformation of the Earth’s surface, such as the biological oxidation of sulphide ore deposits when sulphide minerals are in contact with air and water (Ehrlich 1996, 2004, Johnson 2006). In the late 1940s the recognition of the role of microorganisms in the formation of acid mine waters by the degradation of sulphide minerals (Colmer and Hinkle 1947) eventually led to the introduction of biotechnological principles into hydrometallurgy and to the development of mineral biotechnology known as biohydrometallurgy. It is, therefore, based on the exploitation of the economic potential of the interactions between microorganisms and metals/ minerals in aqueous environments. In this context, mineral biotechnology embraces a diverse range of disciplines, mainly hydrometallurgy, geomicrobiology, microbial ecology and microbial biochemistry (Cupp 1985, Rossi 1990).
