Thiobacillus Ferrooxidans

The following details of the phisiology of the Thiobacillus ferrooxidans will be useful as a help in the understanding of the factors which affect the velocities of lixiviation.

The Thiobacillus ferrooxidans is gram-negative, it does not form spores, it is of long form, its measurements are of 0.5 x 0.7-1.5 micrones. It is moved by a simple polar whipping. The metabolic activity is reduced in presence of sunlight.

Source of Carbon
The bacteria is an autotrophous which requires of CO2 as its only source of carbon. The glucose can be absorbed slowly during the oxydation of the iron and sulphur. The bacteria uses the CO2 of the atmosphere, the optimal concentration is that of 2%

Source of Nytrogen
The NH4 is the main source, even though the urea can replace the amoniac with a small loss in activity. The bacteria can use many aminoacids as a source of nytrogen, but the activity is much less.

Sources of Energy
The ferrous iron and all the forms of reduced inorganic sulphur are used. The speed of respiration of the bacteria is much higher over iron than over substracts of sulphur.

pH
The optimal pH varies with the substract within a range of 2 to 3.5. the limits for the growth are approximately between pH 1 to 5.

Temperature
The speed of optimal growth is at a temperature of 28°C and the optimal speed of respiration is at 37°C. The speeds fall very abruptly above 40°C and all activity ceases at 50°C.

Oxygen
The microorganism requires of large amounts of oxygen with values up to 22,000 ul/mg/h when it is developed over iron.