CONSERVATION OF PLASMID-ENCODED DIBENZOTHIOPHENE DESULFURIZATION GENES IN SEVERAL RHODOCOCCI

The cloned sulfur oxidation (desulfurization) genes (sox) for dibenzot hiophene (DBT) from the prototype Rhodococcus sp. strain IGTS8 were us ed in Southern hybridization and PCR experiments to establish the DNA relatedness in six new rhodococcal isolates which are capable of utili zing DBT as a sole sulfur source for growth. The ability of these stra ins to desulfurize appears to be an exclusive property of a 4-kb gene locus on a large plasmid of ca. 150 kb in IGTS8 and ca. 100 kb in the other strains. Besides a difference in plasmid profile, IGTS8 is disti nguishable from the other strains in at least the copy number of the i nsertion sequence IS1166, which is associated with the sox genes.