 Approximately 25% of all copper mined worldwide is now obtained from leaching processes.The acidophilic archaea "Sulfolobus metallicus" and "Metallosphaera sedula" tolerate up to 4% of copper and have been exploited for mineral biomining.Between 40 and 60% copper extraction was achieved in primary reactors and more than 90% extraction in secondary reactors with overall residence times of about 6 days.