Abstract

Predefined mixed cultures ofAcidithiobacillus ferrooxidans,Acidithiobacillus caldusandAcidithiobacillus thiooxidansstrains were used to stimulate marmatite bioleaching under different temperatures. Changes in this simple bacterial community over time during the leaching process were evaluated using denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA gene fragments.A. ferrooxidansandA. calduswere detected in all samples taken at 5-d intervals during a 41–46 days bioleaching process. The presence ofA. thiooxidansin the initial inoculum stimulated bioleaching, however the relative population ofA. thiooxidansgradually declined, and this species was not detected after 30 day (at 30 °C) or 15 days (at 35 °C). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) analyses revealed the production of S⁰and jarosite during bioleaching. Bacteria were observed to be attached to mineral surfaces. Results suggested thatA. ferrooxidansandA. caldustogether could perform marmatite bioleaching, and thatA. thiooxidanscould promote the bioleaching of marmatite byA. ferrooxidansandA. caldus. This study improves the understanding of marmatite bioleaching at different temperatures.