The objective of this work was to assess the microbial populations and its activities involved in the S cycle, of virgin and cultivated soils, and its relationships with the different fractions of S in the soil. The influence of soils with different vegetations on microbiological and biochemical characteristics was investigated. Out of the different populations of microorganisms examined, only the S0-oxidizing autotrophic bacteria and thiosulfate-oxidizing heterotrophs that represented less than 0.1% of the total bacteria were found. The average of autotrophs was double that of the heterotrophs. The highest counts of total bacteria, autotrophic and heterotrophic microorganisms were found in corn, pasture and forest soils, respectively. Arylsulfatase activity was greater in forest soil, and rhodanese activity in pasture soil. Arylsulfatase correlated with heterotrophic populations, organic C, total S, organic S, organic matter and soil moisture; and rhodanese with organic C, total S, and organic S. The contents of organic S and sulfate were of 94-98% and 2-6% of total S, respectively. The major content of total S and organic S was found in the forest soil. Total S correlated significantly with organic S, moisture and organic matter and organic S with organic matter.
bacteria; oxidation; arylsulfatase; rhodanese
