Column bioleaching of low-grade copper ore by Acidithiobacillus ferrooxidans in pure and mixed cultures with a heterotrophic acidophile Acidiphilium sp.

The aim of this investigation was to compare a pure culture of Acidithiobacillus ferrooxidans GF with a mixed culture with Acidiphilium sp. DX1-1 in the bioleaching of low-grade copper ore. The leaching experiments were carried out at ambient temperature. The influence of temperature, pH, redox potential and concentration of total iron and ferric ion in solution on the performance of column bioleaching was also investigated. Total DNA was extracted from the mineral samples taken at different depths from the column top surface, and the corresponding microbial community structures were examined using amplified ribosomal DNA restriction analysis (ARDRA). Copper extractions by the pure and mixed cultures achieved 14.87% and 20.11% respectively over a period of 117 days, including 15 days of acid pre-leaching and 102 days of bioleaching. The ratios between autotrophic and heterotrophic bacteria at the top and bottom portions of the columns were 1.20:1 and 2.14:1, respectively.