International Journal of Applied Environmental Sciences

Coal mine spoil is a unique geomorphic system with several hostile environmental parameters, but not sterile, and support bacterial community that has physiological adaptability to thrive in such hostile condition. Thiobacillus thermosulfatus was isolated from fresh coal mine overburden spoil sample in medium-A enriched with elemental sulfur. The bacterium was found to be gram negative, motile, rod shaped, facultatively autotrophic, strictly aerobic. The bacterium showed diauxic growth in medium-A due to the availability of thiosulfate as first nutrient followed by tetrathionate produced as intermediate in the medium with the corresponding change in pH from 6.0 to 2.1 during the bacterial growth. Optimum growth of Thiobacillus thermosulfatus was obtained at pH 5.2 to 5.6 and temperature 50°C to 53°C, suggesting that the bacterium is acidophilic and moderately thermophilic. Specific growth rate (μ) of the bacterium in medium-A supplemented with thiosulfate was calculated to be 0.236hr⁻¹. Further, Thiobacillus thermosulfatus grows autotrophically on thiosulfate, elemental sulfur and tetrathionate, and heterotrophically on yeast extract, succinate and glutamate. Thermal death time of the bacterium in chemolithotrophic culture condition was found to be 1hr at 80ºC.