THIOSULFATE AND TETRATHIONATE DEGRADATION AS WELL AS BIOFILM GENERATION BY THIOBACILLUS-INTERMEDIUS AND THIOBACILLUS-VERSUTUS STUDIED BY MICROCALORIMETRY, HPLC, AND ION-PAIR CHROMATOGRAPHY

The growth of Thiobacillus (T.) intermedius strain K12 and Thiobacillu s versutus strain DSM 582 on thiosulfate and tetrathionate was studied combining on-line measurements of metabolic activity and sulfur compo und analysis. Most results indicate that T. intermedius oxidized thios ulfate via tetrathionate to sulfate. Concomittantly, sulfur compound i ntermediates like tri- and pentathionate were detectable. The formatio n is probably the result of highly reactive sulfane monosulfonic acids . The formation of tetrathionate allows the cells to buffer temporaril y the proton excretion from sulfuric acid production. With T. versutus intermediate sulfur compounds were not detectable, however, sulfur wa s detectable. The possibility of a thiosulfate oxidation via dithionat e, S2O62-, is discussed. The on-line measurment of metabolic activity by microcalorimetry enabled us to detect that cells of T. intermedius adhere to surfaces and produce a biofilm by a metabolic process wherea s those of T. versutus fail to do so. The importance of the finding is discussed.