Abstract
Iron-oxidizing bacteria {e.g. Thiobacillus ferrooxidans、are known as an influential catalyst of soil acidification in primary oxidization of pyritic soils. We have reported that multiplication rate of the bacteria is influenced by soil moisture. In this paper, we tried to estimate the configuration of the microhabitat of T. ferrooxidans under three different soil moisture conditions ( — 3.5 kPa, —35 kPa, and —3000 kPa) to look into the mechanism of bacterial oxidation in detail measuring the number of adsorbed and free form of the bacteria (AFT and FFT) using incubation and centrifugation method. At the beginning of the soil incubation, most T. ferrooxidans were counted as AFT in every soil moisture condition. Multiplication rate of both forms of bacteria under the condition of —35 kPa was highest of all conditions. Under the condition of —3.5 kPa, the survival rates of both forms of bacteria were higher especially in AFT. And under the condition of —3000 kPa, FFT could not be counted and a small number of AFT remained at the first stage of incubation, which did not live long. These data indicate that population dynamics of T. ferrooxidans in soil matrix is influenced by soil moisture conditions.
