Effect of pulp density on planktonic and attached community dynamics during bioleaching of chalcopyrite by a moderately thermophilic microbial culture under uncontrolled conditions

• Effect of pulp density on free and attached community dynamics were investigated.
• Succession of attached cells is very different from their planktonic counterparts.
• The proportions of attached cells are higher than that of planktonic cells.
• F. thermophilum and A. caldus preferentially attached to mineral surface.

An enriched and adapted moderately thermophilic culture showed good performance during bioleaching of chalcopyrite under uncontrolled conditions. The copper extractions were up to 85.0%, 77.3% and 56.3% at pulp densities of 10%, 15% and 20% (w/v) within 22 days, respectively. The real-time quantitative PCR was employed to monitor planktonic and attached community dynamics during bioleaching of chalcopyrite by the moderately thermophilic microbial culture. Only three species, including Acidithiobacillus caldus, Sulfobacillus acidophilus and Ferroplasma thermophilum, were detected during the whole bioleaching process. The results show that pulp density had significant effects on planktonic and attached microbial community dynamics. The succession of attached cells was different from community dynamics of their planktonic counterparts. F. thermophilum and A. caldus preferred to attach to mineral surface, especially at pulp densities of 15% and 20%.

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