Bioleaching of chalcopyrite by UV-induced mutagenized Acidiphilium cryptum and Acidithiobacillus ferrooxidans
(Key Laboratory of Biometallurgy of Ministry of Education of China,
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: The original strains Acidithiobacillus ferrooxidans GF and Acidiphilium cryptum DX1-1 were isolated from the drainage of some caves riched in chalcopyrite in Dexing Mine in Jiangxi Province of China. The optimum temperature and pH for growth were 30 ℃ and 3.5 for Ac. cryptum DX1-1, and 30 ℃ and 2.0 for At. ferrooxidans GF, respectively. For Ac. cryptum DX1-1, the optimum UV radiating time was 60 s and the positive mutation rate was 22.5%. The growth curves show that Ac. cryptum after mutagenesis reached stationary phase within 60 h, which was 20 h earlier than the original strain. For At. ferrooxidans GF, the optimum mutation time was 60 s and the positive mutation rate was 35%. The most active UV-mutated strain At. ferrooxidans GF oxidized all the ferrous after 48 h. The bioleaching experiments showed that bioleaching with the mixture of UV-mutated strains of At. ferrooxidans GF and Ac. cryptum DX1-1(1׃1) could extract 3.01 g/L of copper after 30 d, while the extracted copper was 2.63 g/L with the mixture of the original strains before UV-mutation. At the end of the bioleaching experiments, the proportion of the cell density in the cultures of Ac. cryptum DX1-1 and At. ferrooxidans GF was approximately 1׃5.
Key words: Acidiphilium cryptum; Acidithiobacillus ferrooxidans; UV-induced mutagenesis; bioleaching; chalcopyrite