Thiobacilli and sulphate production from inorganic sulphur compounds in upper horizons of spruce forest soils.

The species representation of Thiobacilli was investigated in horizons F, H and A of spruce forest at ten localities. Concentrations of Thiobacilli in the selected localities and ability of the soils to oxidize sulphur compounds to sulphate were determined. Horizons F exhibited a high oxidative activity, a lower activity was found in horizon H and the lowest one was detected in horizon A. The activities showed spring and autumn maxima. Horizons F, H and A contained 10(4)--10(5), 10(2)--10(3) and 10(1)--10(3), respectively, Thiobacilli in 1 g dry soil. Thiobacillus thioparus was detected in all three horizons from all localities, T.thiooxidans was found in all horizons F, only in some horizons H and was not detected in horizons A. T.novellus was found only in some samples without any relation to the horizons, T.denitrificans was not detected at all.