[Functioning of integrative vectors, based on phage phi C 31, in the strain Streptomyces bambergiensis 712]

Actinomycete integrative vectors were constructed. The vectors contain the Escherichia coli plasmid ColE1 replicon, the thiostrepton resistance gene used for selection in Streptomyces and a fragment of the phi C31 actinophage genome with integrative functions. The pS133 and PS135 vector DNAs transformed Streptomyces bambergiensis 712, a strain producing the phosphoglycolipid antibiotic moenomycin. Two types of the transformants were detected. The first type was not affected in the ability to produce moenomycin and the vector pS135 DNA was shown to integrate into the S. bambergiensis 712 genome by the site-specific pattern with the psi C31 phage DNA fragment. The second type of the transformants lost the ability to produce moenomycin. The Southern analysis and cloning of the inserted DNA indicated that in this case the vector pS135 and pS133 DNAs also integrated specifically into the genome but the integration took place not within the phage DNA fragment. Its realization was suggested to proceed via homologous recombination.