Mineral sulphide oxidation by enrichment cultures of novel thermoacidophilic bacteria

Abstract: Enrichment culture of hot spring water samples with pyrite as substrate has provided acidophiles with novel growth characteristics: with these bacteria, the range of conditions under which rapid microbial oxidation of mineral sulphides has been demonstrated has been extended. The upper temperature limit for bacterial mineral oxidation in reactors has been raised. The dissolution of pyrite occurred during growth of Sulfolobus -like thermophiles up to almost 90C. The most efficient extraction of copper from chalcopyrite occurred at 80–85C. With moderate thermophiles, rapid oxidation of minerals was obtained during autotrophic growth in the absence of supplemental CO₂: a mixed enrichment culture was active in pyrite dissolution at 45–50C in reactors gassed only with air which contrasted with poor growth by well-studied moderate thermophiles in the absence of enhanced CO₂ concentrations.