CHARACTERIZATION OF A NEW METAL-MOBILIZING THIOBACILLUS ISOLATE

A new acidophilic, mineral sulphide ore-oxidizing bacterium was isolated from a uranium mine near Salamanca, Spain. Cells were rod-shaped, motile and gram-negative. They were aerobes, could grow on pyrite and use sulphur or thiosulphate as sole energy source, suggesting this new isolate belongs to the genus Thiobacillus. It could grow neither with glucose nor with yeast extract as sole substrates. It could not grow on ferrous sulphate as the only energy source, although it grew in the same medium supplemented with glucose, yeast extract or thiosulphate. It was a mesophilic and extremely acidophilic Thiobacillus, with an optimal pH of 1.5-2. The G + C content of the DNA was 58%. The new isolate could grow in cultures on pyrite where both sulphur and iron became oxidized. Its protein electrophoretic pattern was clearly different from those of other thiobacilli, such as T. ferrooxidans.