Thiobacillus neopolitanus R-10, which produces a active thiosulfate oxidase, was isolated from nightsoil. The optimal culture conditions of Thiobacillus neopolitanus R-10 for the production of enzyme was determined as followed: 0.8% Na2S203, 0.2% KH2P04, 0.2% K2HP04, 0.04% Na2C03, 0.02% MgSO4·7H2O, 2ml trace elements solution, and pH 6.5 at 30℃ and 72hr cultivation. The oxidase was successively purified 83 folds yield by (NH2)2S04 fractionation, DEAE-Cellulose, Sephadex A-50 column chromatogrophy and gel Sephadex G-150 gel filteration with yield of 5.9%. The molecular weight of purified enzyme was estimated to be 43.000 dalton by SDS-polyacrylamide gel electrophoresis and gel filteration column chromatography. The enzyme activity was highest at 40℃ and pH 7.0 The enzyme activity was relatively high by β-mercaptoethanol but strongly inhibited by cysteine.

Continuous deodorization of malodorous sulfur compounds by Thiobacillus neapolitanus R-10 immobilized onto a polypropylene pellet was studied using a column reactor at 30℃. The maximum amounts of immobilized cells was 5.3 g/ℓ polypropylene with 5 × 7.5㎜ in pellet size, and the amounts of immobilized cells in the higher part of the column was as twice as in the lower part. The optimum pH and temperature for removal of dimethyl sulfide were 6.0 and 30℃, respectively. When 5-20 ㎕/ℓ of hydrogen sulfide and methylmercaptan were employed 98% of removal efficiency were achieved. In contrast, lower concentrations of dimethyl sulfide and dimethyldisulfide should be supplied to meet satisfactory deodorization efficiency. The immobilized cell column was successfully operated for the deodorization of mixture of sulfur compounds over 15 days without significant loss of initial activity achieving high efficiency.