Microbial Conversion of Petro-sulfur Compounds

Abstract

In order to enhance the efficiency converting dibenzothiophene (DBT) into water-soluble compounds by DBT-utilizing bacteria, the following subjects were studied: comparison of activities of isolated strains, their mixed cultivation, DBT dosing, nitrogen sources, substrate concentration, pH, temperature, and oxygen supply. Light oil solution of DBT (5%) was used as substrate. The conversion efficiency was calculated by the amount of sulfur accumulated in the aqueous layer of culture broth. The conversion ratio of 40% was attained by the mixed culture of Pseudomonas abikonensis and Ps. jianii under the following conditions; medium, DBT 4.6g dissolved in 87.8g of light oil, meat extract 4.0g, Na2HPO4.12H2O 9.5g, KH2PO4 1.4g, MgCl2.6H2O 0.2g, distilled water 1000ml; pH, 6.9 to 7.3 (M/30 phosphate buffer); oxygen supply, 50ml broth 500ml flask, shake culture at 220 rpm; inoculum size, 10%; temperature, 28°C; and period of cultivation, 3 days.