Microbiological oxidation of ferrous iron at low temperatures.

Acidophilic iron-oxidizing bacteria were enriched from mine water samples with ferrous sulfate as the substrate at incubation temperatures in the range of 4 to 46 degrees C. After several subcultures at each test temperature except 46 degrees C, which was prohibitive to growth, the rates of iron oxidation were determined in batch cultures. The results yielded linear rates in a semilogarithmic scale. The rate constants of iron oxidation by growing cultures were fitted into the Arrhenius equation, which displayed linearity in the 4 to 28 degrees C range and yielded an activation energy value of 83 +/- 3 kJ/mol.