Molecular genetic study of Streptomyces virginiae, the producer of virginiamycin

The level and the character of the Streptomyces virginiae virginiamycin-producing strain's resistance to self-produced antibiotic and a number of antibiotics from different groups were determined. S. virginiae was shown to display constitutive and inducible resistance to self-produced antibiotic. The phenomenon of cross-inducible resistance of the strain to virginiamycin and the antibiotics erythromycin, oleandomycin, and thiostrepton was demonstrated. The pTO1 and pVGTB24 plasmids were introduced into the strain by the method of intergeneric conjugation with Escherichia coli. Site-specific integration of the pTO1 vector into the S. virginiae chromosomal attB site without disturbance of growth, differentiation, and productivity of the strain was shown, The multicopy autonomously replicating plasmids pIJ699, pIJ702, pWOR109, and the integrative pZAT22 plasmid were introduced into the strain via electrotransformation of germinating spores. The efficiency of transformation was 1-5 x 10(3) transformants per 1 mu g DNA. The stable inheritance of the plasmids in S. virginiae without structural rearrangements was shown. These results allow the use of these plasmids to clone genes into S. virginiae.