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• Effects of microbial types and diversity on chalcopyrite bioleaching were studied. • Community with more sulfur oxidizers and high diversity showed high Cu recovery. • Microbial types showed greater influences on mineral dissolution than biodiversity. • A. caldus enhanced CuFeS 2 extraction greatly by regulating physicochemical factors. Six artificial communities with different function or biodiversity were reconstructed by six typical bioleaching species for chalcopyrite leaching. Absence of sulfur oxidizers in communities significantly reduced copper extraction rates, and low diversity communities also exhibited slightly poor bioleaching performances. The variations of pH, redox potential, ferrous and copper ions indicated that the community with both sulfur oxidizers and high diversity showed fast adaptation to the environment and rapid dissolution of chalcopyrite. Integrated analysis of mineralogical and microbial parameters demonstrated that functional types of microorganisms made more contributions in mediating chalcopyrite dissolution than microbial diversity. Further correlation analysis between microbial types and chalcopyrite dissolution performances showed that sulfur oxidizers, especially Acidithiobacillus caldus , could greatly accelerate chalcopyrite dissolution by regulating solution physicochemical factors, such as redox potential and pH. This study provided a theoretical basis for improving bioleaching efficiency by balancing microbial functional types and biodiversity. [ABSTRACT FROM AUTHOR]

Bioleaching has been widely applied to recover sulfide minerals, however, little is known about the bioleaching behavior and mechanism of mixed oxide-sulfide copper ore with high-oxidative ratio. The leaching efficiency of artificial indigenous and exogenous microbial communities on a mixed oxide-sulfide copper ore with and without energy substrate was investigated. The results indicated that extra energy substrate was needed when bioleaching was applied to this kind of ore. The variation of leaching parameters caused by indigenous community was inferior to that caused by exogenous ones due to its lower activity. The leaching efficiency of sulfide part induced by indigenous strains was superior to that induced by exogenous ones, due to the stronger colonization ability of indigenous strains. It verified that both microbial activity and colonization ability were important properties affecting leaching efficiency. Sulfur oxidizers, which can oxidize sulfur or polysulfide formed on mineral surface and decrease leachate pH, played a more important role than ferrous oxidizers in bioleaching of high-oxidative oxide-sulfide ore. [ABSTRACT FROM AUTHOR]

Toxic ions accumulation in leachate is one of the limitations for bioleaching application. The effects of fluoride ions on microbial growth relevant to bioleaching have been extensively emphasized. However, the reasons that the microorganisms present different fluoride tolerance in bioleaching of different minerals have not yet been proposed. A fundamental exploration on the differential fluoride tolerance of sulfur- and ferrous iron-grown Acidithiobacillus ferrooxidans was performed. The results showed that the critical fluoride concentration for sulfur-grown A. ferrooxidans was less than 0.1 mM whenever fluoride was introduced. The critical fluoride concentration for ferrous iron-grown A. ferrooxidans was 1.0 mM when fluoride was introduced prior to the lag phase, but it was higher than 10.0 mM when fluoride was introduced at the log phase. The ferric ions generated from ferrous oxidation could significantly decrease the concentration of HF and finally reduce the toxicity of fluoride to A. ferrooxidans . The changes of concentration of metal ions with strong complex ability to fluoride ions, resulted in an illusion of high fluorine-resistant strain in industrial bioleaching heap. Finally, the feasibility of fluoride removal by ferric ion was put forward. This work has meaningful implications for the industrial bioleaching of high-fluorine containing uranium ore. [ABSTRACT FROM AUTHOR]

• Typical low-grade copper ores and their corresponding pure isolates were obtained. • Cross bioleaching of low-grade copper ores was firstly conducted. • Longitudinal domestication was an effective way to improve bioleaching performance. • Population regulation was another effective way to improve bioleaching efficiency. The interaction between microorganisms and minerals was a hot topic to reveal the transformation of key elements that affecting bioleaching efficiency. Three typical low-grade copper ores, the main copper-bearing components of which were primary sulfide, secondary sulfide and high-oxidative sulfide copper, were obtained from Dexing, Zijinshan and Luanshya copper mine, respectively. Meanwhile, six typical microorganisms were isolated from each of the three habitats, and assembled as communities based on their origins. Cross bioleaching was carried out under identical conditions. The leaching parameters showed that native strains played excellent roles in their corresponding ore bioleaching process, and community structure was greatly determined by mineral composition, indicating that domestication for longitudinal adaption was an effective way to improve microbial leaching performance. Leptospirillum ferriphilum and Acidithiobacillus ferrooxidans promoted copper release by shifting redox potential and pH of the leachate, respectively, indicating that microbial population regulation was another effective way to improve bioleaching efficiency. [ABSTRACT FROM AUTHOR]