DEGRADATION CHARACTERISTICS OF HYDROGEN-SULFIDE, METHANETHIOL, DIMETHYL SULFIDE AND DIMETHYL DISULFIDE BY THIOBACILLUS-THIOPARUS DW44 ISOLATED FROM PEAT BIOFILTER

A bacterium, capable of the degradation of hydrogen sulfide (H2S), methanethiol (MT), and dimethyl sulfide (DMS), as well as dimethyl disulfide (DMDS), was isolated on a thiosulfate plate from a suspension of DMDS-acclimated peat. The isolate was identified as Thiobacillus thioparus on the basis of its morphological, physiological and chemotaxonomical characteristics. The specific uptake rates (g-S.cell-1.h-1) of these sulfur compounds in the basal medium were determined as 7.49 x 10(-14) for H2S, 3.45 x 10(-14) for MT, 4.14 x 10(-15) for DMS and 1.23 x 10(-14) for DMDS. When this strain was inoculated in sterilized fibrous peat, the maximum removal rates (V(m); g-S.kg-dry peat-1.d-1) of each gas singly by the peat biofilter were obtained by the application of the Michaelis-Menten equation: V(m) (H2S) = 5.52, V(m) (MT) = 1.16, V(m) (DMS) = 0.50 and V(m) (DMDS) = 1.02. The specific uptake rates estimated for these compounds by this strain on the fibrous peat were similar to those in the basal medium. This strain also simultaneously degraded H2S, MT and DMS in a mixture of the three gases, although the removal ratio of DMS in the mixed gases decreased compared with that in the case of the single gas. The removability of DMS was inhibited by the presence of MT, but accelerated by the presence of H2S.