This paper describes the microbiology basics underlying heap and tank biooxidation of metal sulfide ores and concentrates. The primary organisms are identified and described along with the reactions they catalyze and their growth requirements. Also described is the interaction between ore-leaching bacteria and the leaching environment in terms of solution chemistry, temperature and mineral precipitation. Specific factors and agents that stimulate or inhibit growth and activity of ore bioleaching are identified. Some of these factors are organism-specific and others are generic for microorganisms that grow under acidic conditions. The current knowledge of the limits of bioleaching in terms of dissolved ions in leach solutions, pH and temperature is summarized.
