鉄酸化細菌の塩素イオン阻害に及ぼす珪藻土の効果

Abstract

This paper describes an inhibition of oxidation and growth of Thiobacillus ferrooxidans by chloride ion and the effect of diatomaceous earth against its inhibition. Ferrous ion oxidation experiment in the absence of nutrient salts was carried out with various amount of chloride ion. The assay solution of this experiment contained only ferrous sulfate and magnesium sulfate (pH 1.5), and no bacteria grew in this condition. The oxidation of ferrous ion was inhibited by the chloride ion, and was subjected to the competitive inhibition from the Lineweaver-Burg plot. The addition of the diatomaceous earth in assay solution had no effect on the bacterial oxidation. The growth of T. ferrooxidans in 9 K medium was also inhibited by the chloride ion. The growth kinetics of this bacterium in the presence of chloride ion were described with the modified Monod type equation including the term of inhibitor concentration. The growth inhibition reduced by the addition of diatomaceous earth in the medium. The oxidation rate in the presence of diatomaceous earth was much faster than that in the absence of it in high concentration of chloride ion. The growth inhibition constant of adsorbed bacteria was about 60 % larger than that of free bacteria, which was the reason the oxidation of ferrous ion in the presence of diatomaceous earth was faster. The adsorption amount of T. ferrooxidans onto the diatomaceous earth was almost constant in this experimental range of the chloride ion.