Oxidation of reduced inorganic sulphur compounds by acidophilic thiobacilli

Abstract

Acidophilic sulphur-oxidizing bacteria were first isolated from acidic mine effluents [1], where they are the causative agents of the environmental problem acid mine drainage. Furthermore, acidophilic thiobacilli are at least partially responsible for the development of acid sulphate soils [2]. Over the past decades there has been a growing interest in the application of this type of organisms in the biological leaching of metal ores [3] and the biological dcsulphuriz~tion of coal [4,5]. The key reaction in the processes mentioned above is the biological oxidation of pyrite (Fe:S2) to ferric sulphate and sulphuric acid. Thiobacillus ferrooxidans is widely used as a model organism to study the biological oxidation of pyrite. T. ferrooxidans is an obligately chemolithoautotrophic, aerobic. Gram-negative bacterium. Energy sources for autotrophic growth include ferrous iron and a number of reduced inorganic sulphur compounds [6]. Most studies into the physiology and bio-en-