Abstract: A process for treating sulfide ores to reduce the sulfur content or recover the metal content therefrom comprises the use of enzymatic action to solubilize the sulfur and metal content.A nutrient, such as a saccharide, is used along with yeast spores which feed on the sugar and produce enzymes which act on sulfur in the sulfide ore to cause the sulfur to go into solution and to dissolve those metals which are soluble in strongly acidic solution. Sulfuric acid can be formed from the sulfide ores or from free sulfur by reaction with water, with evolution of hydrogen sulfide gas. Oxidation of at least a portion of the hydrogen sulfide can be achieved to regenerate sulfuric acid.