Study On Characteristics Of Cultivation Of Acidithiobacillus Ferrooxidans And Its Effects On Bioleaching Of Phosphate Ore

It has been reported about the description of the bacteriology since thiobacilluswas found, and report has also been made on Acidithiobacillus ferrooxidans------oneof the thiobacillus used mainly in the leaching of ores. In this dissertation, we research about the isolation and purification of Acidithiobacillus ferrooxidans which was isolated from acid mine drainage from a coal mine in Anhui and the leaching of low grade phosphate ore by experiments.The results of enrichment experiments indicated that bacterium grew well under the conditions of: culture temperature 30 °C, initial pH 3.08, quantity of inoculation 10% and using 9K culture medium; In the experiment of isolation and purification, it is adopted diluting and smearing slab to isolate and purify. During the experiments through changing the ingredient of plate, it is evaluated by the days of appearance and numbers of colony. It is affected by the following factors:(1) The basic reason for the colony formation inhibition is that the culture medium acidity is too high for baterial oxidation to prevent agar from peptoned and keep invariable pH for the inoculum , in which the bacterium can stably anchorage on the medium for growth and multiplication. Regulating the culture medium composition, can overcome this state to a great extent. As the concentration of Fe²⁺ in 9K solid culture medium was 4.5 g/L, it has a better colony separating result of At. f.(2) The high concentration of dissolved organic matter, which is toxic to chemoautotrophic Acidithobacilli bacteria, released from agar with autoclave were responsible for the lower colony count efficiency for single-layer plate. On the contrast, the yeast strain lived in underlayer consumed a lot of dissolved organic matter in medium, resulting in a higher colony count efficiency for double-layer plate. The experiments proved that adopting a double-layer plate, with heterotrophic microbe Rhodotorula sp. spread onto the bottom layer and chemoautotrophic bacterium At. f spread onto the upper layer is in favor of the formation of At. f colony.According to the bacterial identification experiments, we can preliminarily judge that the strain which was isolated from acid mine drainage from a coal mine was identified as Acidithiobacillus ferrooxidans.The influential factors including culture media, energy source materials and the addition of surfactant on the leaching of phosphate ore with the cultivated At. f were studied. It is estimated by pH, the bacteria density and the rate of leaching of phosphate ore. It is concluded that up to 44.16% of phosphate in the ore was leached...