The Mixed Culture Of Thiobacillus Ferrooxidans And Thiobacillus Thiooxidans And Their Leaching Mechanism On Copper

With the development of bioleaching, people pay more attention to the bacteria which play important role in the course of bioleaching. The bacteria derives the energy required for its growth from the oxidation of Fe²⁺, S⁰, and other metal ions are different and mixed bacteria can raise the bioleaching rate, thus mixed bioleaching has become one of hot research today. Thiobacillus ferrooxidans (T.f) is one of the worth bacteria in the course of bioleaching, in some special conditions Thiobacillus thiooxidans (T.f) can reinforce the bioleaching ability ofT-f.In this thesis, a strain of T.t was isolated from acid mine drainage (AMD) and identified in morphological, and domesticated in the high concentrations of Cu²⁺ and copper mine. The results demonstrated: this T.t is the gram-negative chemolithotrophic obligate bacterium, which derives the energy required for its growth from the oxidation of S°. The wide T.t can only tolerance low concentration of Cu²⁺;The adapted T.t is quite resistant to the high concentration of Cu²⁺ and it's oxidation ability of S° under 20g/L Cu²⁺ is improved by several generation demonstrated culture, moreover, the proteins of outer membrane in adapted T.t are different to the wide T.t.We also do some research for low-grade chalcopyrite in the shake flask, our results demonstrated: at the pH1.8;in the culture medium: (NH₄)₂SO₄ 66mg, K₂HPO₄ 35mg, MgSO₄·7H₂O 123mg, FeSO₄·7H₂O 2.95g, S 0.344g,H₂O 1000ml;10⁸ cell/ml T.f, T.t are inoculated;the diameter of ores ≤50μm and the concentration of ore is 5%, we can have the best bioleaching rate. Added the catalyzing Ag⁺, the bioleaching rate of Cu²⁺ is improved. The X-ray diffraction analysis results demonstrated, the T.f have a direct function in the dissolution of the chalcopyrite, but the T.t have an indirect function via Fe³⁺.The bioleaching ability of T.f is responsible for its energy ability, studying the respiratory mechanisms makes for the understanding of the role of energy metabolism in the bioleaching process. Cyc2 protein is the primary electron acceptor of iron respiratory chain;S⁰, Fe²⁺ and other electron donors regulate the synthesis of Cyc2 proteins. Basing on these deduction, the wide BY3 separated and demonstrated from our lab was used as the target strains to study. We prepared the outer membrane fractions of different strains of BY3 to identify the difference of their Cyc2 proteins with Cyc2 specific antibodies donated by Professor Bonnefoy throughSDS-PAGE and western blotting. The results showed that the molecular mass of Cyc2 in the adapted BY3 is less than the wide BY3. The expression of Cyc2 in the wide BY3 and adapted BY3 has direct relation to their oxidation rate. The expression of Cyc2 in the adapted copper mine BY3 is obviously less than other strains.