title: Investigation of energy gene expressions and community structures of free and attached acidophilic bacteria in chalcopyrite bioleaching.
abstract: In order to better understand the bioleaching mechanism, expression of genes involved in energy conservation and community structure of free and attached acidophilic bacteria in chalcopyrite bioleaching were investigated. Using quantitative real-time PCR, we studied the expression of genes involved in energy conservation in free and attached Acidithiobacillus ferrooxidans during bioleaching of chalcopyrite. Sulfur oxidation genes of attached A. ferrooxidans were up-regulated while ferrous iron oxidation genes were down-regulated compared with free A. ferrooxidans in the solution. The up-regulation may be induced by elemental sulfur on the mineral surface. This conclusion was supported by the results of HPLC analysis. Sulfur-oxidizing Acidithiobacillus thiooxidans and ferrous-oxidizing Leptospirillum ferrooxidans were the members of the mixed culture in chalcopyrite bioleaching. Study of the community structure of free and attached bacteria showed that A. thiooxidans dominated the attached bacteria while L. ferrooxidans dominated the free bacteria. With respect to available energy sources during bioleaching of chalcopyrite, sulfur-oxidizers tend to be on the mineral surfaces whereas ferrous iron-oxidizers tend to be suspended in the aqueous phase. Taken together, these results indicate that the main role of attached acidophilic bacteria was to oxidize elemental sulfur and dissolution of chalcopyrite involved chiefly an indirect bioleaching mechanism.
authors.affiliation: School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, People's Republic of China.
authors.forename: Jianyu
authors.initials: J
authors.lastname: Zhu
authors.forename: Weifeng
authors.initials: W
authors.lastname: Jiao
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Xueduan
authors.initials: X
authors.lastname: Liu
authors.forename: Wenqing
authors.initials: W
authors.lastname: Qin
authors.forename: Guanzhou
authors.initials: G
authors.lastname: Qiu
authors.forename: Yuehua
authors.initials: Y
authors.lastname: Hu
authors.forename: Liyuan
authors.initials: L
authors.lastname: Chai
mesh_terms: D013856:Acidithiobacillus thiooxidans / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D000143:Acids / Q000378:metabolism; D001419:Bacteria / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001422:Bacterial Adhesion; D003300:Copper / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D004734:Energy Metabolism / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D060888:Real-Time Polymerase Chain Reaction; D013455:Sulfur / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000143:Acids; C012819:chalcopyrite; D013455:Sulfur; D003300:Copper; D007501:Iron