Iron Oxidation not Coupled to Growth in Thiobacillus ferrooxidans in Presence

Growth and iron oxidation by Thiobacillus ferrooxidans are affected by the presence of silver, molybdenum, uranium and copper. Growth is more sensitive to the presence of these metals than the iron oxidation system of the bacterium. Silver toxicity is much more specific than molybdenum and uranium. Iron oxidation is inhibited at only 0.1 parts/10⁶ of silver which is 300 and 5000 times less than the minimum inhibitory concentration of molybdenum and uranium, respectively. Copper and zinc at concentrations as high as 2000 and 15 000 parts/10⁶, respectively, have no influence on the iron oxidation rate. In the presence of silver, molybdenum, uranium and copper below their minimum inhibitory concentrations as well as in the absence of nitrogen, phosphorus and potassium, iron oxidation is not coupled to growth.