Isolation, Identification Of Acidithiobacilius Ferrooxidans And Acidiphilium Spp. And Studies On Their Synergistic Effect Of Leaching Chalcopyrite

Bioleaching is an economical method for the recovery of metals from minerals,especially from low grade ores,overburden and waste from current mining operations,which requires moderate capital investment with low operating cost.Furthermore,bioleaching is generally more environmentally friendly than conventional metal recovery processes such as concentration and smelting.In the present study, several autotrophic bacteria Acidithiobacilius ferrooxidans and heterotrophic bacteria Acidiphilium spp.were isolated and characterized from Acid Mine Drainage(AMD).This research worked on the isolation,physiological and bioleaching characterization of Acidithiobacilius ferrooxidans and Acidiphilium spp..To understand the role of autotrophic and heterotrophic bacteria plays in mineral bioleaching,we focused on the effects of one autotrophic iron and sulfur-oxidizing bacterium A.ferrooxidans GF and its synergistic effect with one heterotrophic sulfur-oxidizing bacteriam Acidiphilium sp.DY on copper dissolution from chalcopyrite.We isolated four autotrophic bacterial Acidithiobacilius ferrooxidans strains from different mining tailings in China,named as GF,LY,DBS and DX.The optimum growth temperature is 30℃,and the optimum growth pH is 2.0.The four strains can grow autographically by using Fe²⁺, sulfur,glucose as sole energy sources,however,can not grow with NaS₂O₃ and peptone.The data of ferrous sulfate and sulfur oxidation of four strains revealed that the activity of them is consentaneous.The relationship is consistent with the ferrous sulfate and sulfur oxidation activity of the four strains,GF＞LY＞DBS＞DX.Because of the high activity of oxidation ferrous and sulfide mineral,strain GF was used in bioleaching of marmatite.The Zn concentration was 273.25mg/L under the steriled control and 7302.5mg/L with adapted GF strain incubated after 30 d in leaching marmatite.The isolated strain GF can be used for leaching marmatite in industry application.25 acidophilic heterotrophic Acidiphilium-like bacterial strains were isolated from eight different mines in China and their physiology was characterized.The optimum growth temperature is 30℃,and the optimum growth pH is 3.5.It can grow facultative heterotrophically by using glucose,lactose,sucrose and elemental sulfur as sole energy sources,but can not grow with FeSO₄.The comparison of 25 Acidiphilium spp.bacterial results by 16S rRNA gene and gyrB gene analysis shows that gyrB gene analysis may provide more accurate information about the microbial community structure than 16S rRNA gene analysis and thus more likely to revealed the true nature of a microbial community.The bioleaching experiment of chalcopyrite in shake flasks and bioleaching column revealed that the acidophilic heterotrophic Acidiphilium sp.DY strain had little efficiency of leaching chalcopyrite, but when coupled with acidophilic autotrophilic bacteria A.ferrooxidans GF,compared with Aferrooxidans GF leaching efficiency,it can increase the chalcopyrite leaching efficiency greatly.Acidiphilium sp.DY has the potential role to enhance the recovery of copper from chalcopyrite by oxidizing the sulfur and reducing the organic compound during the bioleaching progress.The combination of the acidophilic heterotrophic Acidiphilium spp.and acidophilic autotrophilic A.ferrooxidans in chalcopyrite bioleaching improved the copper leaching efficiency.