A moderately thermophilic iron-oxidizing bacterium strain TI-1 produced 74 μmol H2S extracellularly when grown at 45°C for 15 days in 20 mL of ferrous sulfate-5AAG medium (pH 4.0) containing 1.0 % elemental sulfur and 0.31 % L-glutamic acid. Precipitation of copper from a leaching solution by the H2S produced by strain TI-1 was investigated. A leaching solution containg Cu2+ was prepared by the cultivation of Thiobacillus ferrooxidans AP19-3 on a copper concentrate (5.0 %)-medium (pH 2.5) for 15 days. When strain TI-1 was grown for 8 days in a ferrous sulfate-5AAG medium (pH 4.0) containing 1.0 % elemental sulfur, 0.31 % L-glutamic acid and 5 mM Cu2+ from a leaching solution, the Cu2+ in the medium was completely precipitated by the H2S produced by strain TI-1. Growth of strain TI-1 in ferrous sulfate-5AAG medium was not inhibited by 10 mM Cu2+. A moderately thermophilic sulfate-reducing bacterium Desulfotomaculum nigrificans IFO 136987 produced 45 μmol H2S extracellularly when grown at 45°C for 15 days in 20 ml of lactate (0.35 %)-medium. The maximum productivity of H2S by D. nigrificans was observed in the medium with an initial pH of 7.2. The bacterium did not produce H2S in the lactatemedium with a pH less than 6.0. Growth of D. nigrificans in the lactate-medium was completely inhibited by 0.56 mM Cu2+. These results suggest that strain TI-1 is superior to D. nigrificans in the ability to precipitate copper from the acidic leaching solution containing Cu2+.
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology
- Industrial and Manufacturing Engineering