An investigation of biooxidation ability of Acidithiobacillus ferrooxidans using NMR relaxation measurement.

NMR relaxation measurements can provide a simple means for understanding biological activity of cells in solution with known composition. It has the advantage that it is an in situ, non-intrusive technique, and the acquisition is fast. The iron oxidation ability of Acidithiobacillus ferrooxidans was investigated using NMR relaxation measurements. The transversal relaxation is characterized by a time constant, T₂, which is sensitive to the chemical environment. Fe³⁺ ion has more significant T₂ shortening than Fe²⁺ ion. In the presence of A. ferrooxidans in solutions containing Fe²⁺ ion, T₂ shortening was found with increasing time as the bacteria oxidize Fe²⁺ to Fe³⁺ ions. In the optimal growth medium, the bacteria concentration increased 80 times and high iron oxidation rate was found. In 10 mM K₂SO₄ medium, however, bacteria concentration remained almost unchanged and the iron oxidation rate was significantly lower.