Identification of two new sets of genes for dibenzothiophene transformation in Burkholderia sp. DBT1.

A novel genotype for the initial steps of the oxidative degradation of dibenzothiophene (DBT) is described in a Burkholderia sp. strain isolated from a drain receiving oil refinery wastewater. The strain is capable of transforming DBT with significant efficiency when compared to other microorganisms. Its genotype was discovered by investigating insertional mutants of genes involved in DBT degradation by the Kodama pathway. The cloned dbt genes show a novel genomic organization when compared to previously described genes capable of DBT catabolism in that they constitute two distinct operons and are not clustered in a single transcript. Sequence analysis suggests the presence of a sigma54-dependent positive transcriptional regulator that may be involved in the control of the transcription of the two operons, both activated by DBT. The achieved results suggest the possibility of novel features of DBT biotransformation in nature.