Effects of different energy sources on cell adhesion and bioleaching of a chalcopyrite concentrate by extremophilic archaeon Acidianus copahuensis

Bioleaching is an alternative technology for recovering metals from mineral ores; thermophilic microorganisms instead of mesophiles can greatly improve metal solubilization, particularly from refractory mineral species. Acidianus copahuensis is a new species of thermophilic archaea, recently isolated in our laboratory. The effect of culture growth history on the attachment of A. copahuensis to a chalcopyrite concentrate was investigated in shake flasks at 65 °C. Cells adapted to growth with chalcopyrite as energy source showed higher attachment to the mineral concentrate. A. copahuensis cells reached 100% of copper extraction in the bioleaching of chalcopyrite concentrate carried out in shake flasks cultures incubated at 65 °C and pH 2.0. This high bioleaching yield was achieved even at that not so low initial pH value probably because this archaeal species is able to form sufficient amounts of ferric iron but keeping low redox potential (Eh) values. This work also describes the effect of the addition of other energy sources on the bioleaching activity. A. copahuensis achieved the best copper extraction without any addition but copper extraction decreased when alternative substrates were added.