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.