Conjugation and transformation of Streptomyces species by tylosin resistance.

The tlrB gene from Streptomyces fradiae has been cloned and used to construct bifunctional Streptomyces-Escherichia coli shuttle vectors carrying the antibiotic resistance genes to kanamycin-neomycin, thiostrepton and tylosin as selection markers. In the same way, the tlrB gene was subcloned in plasmids including the apramycin resistance gene and the oriT sequence from the plasmid pSET152 to facilitate conjugation of Streptomyces spores. The usefulness of the tlrB gene as tylosin resistance marker was ascertained in Streptomyces lividans, Streptomyces parvulus and Streptomyces coelicolor, but not in Streptomyces clavuligerus. The tlrB gene constitutes a useful selection marker when high-frequency of conjugation/transformation is not required or as secondary marker in recombinant Streptomyces species where thiostrepton and kanamycin have been utilized for primary selection.