Isolation of Dibenzothiophene Utilizing Bacteria and Determining the Optimal Conditions for Utilizing by P13 Isolate

摘要

The aim of this study was obtaining efficient bacteria capable of utilizing Dibenzothiophene that found in petroleum and its derivatives. For this purpose oil contaminated soil samples with a history of oil pollution were collected from 40 different sites in Iraq. Sixty three bacterial isolates were obtained and these isolates capable to utilize dibenzothiophene (DBT). Results showed that most of these isolates capable to grow on DBT. The growth density of bacterial isolates in presence of glycerol (C-source) was more than growth density without presence of glycerol. Twelve efficient isolates (M3, M7, M16, M20, P4, P13, P14, S21-1, S22, S26, S34 and S37, however, P13 isolate was the best one), (cleaved both C-C and C-S bonds of DBT) were candidate for identification. These 12 isolates were identified as: Staphylococcus spp. [6 isolates, (including P13 isolate)], three of them were Staphylococcus aureus . Micrococcus spp. (2 isolates) and one isolate for each genus of Neisseria sp., Pseudomonas sp., Corynebacterium sp. and Bacillus sp. Optimum conditions for utilization of DBT by P13 isolate were investigated. It was found that these conditions are growing this bacterium in basal salt medium (pH 8) containing 0.6 mM DBT and incubated with shaking (150 rpm) at 35°C for 3 days. The GC/MS analysis for the P13 isolate showed that this isolate utilize the DBT as sulfur and carbon source .