STREPTOMYCES-AUREOFACIENS STRAINS AS HOSTS FOR CLONING OF GENES AFFECTING ANTIBIOTIC PRODUCTION

Several mutants of Streptomyces aureofaciens strain were used for protoplast regeneration and plasmid transformation. All tested mutants (excepting R 8/26) were transformable by number of plasmids and shuttle vectors. The transformation of the CTC production strains by plasmid containing cloned CTC resistance gene resulted in 1, 1-4 times higher antibiotic production. From the restriction analysis of plasmid, phage and chromosomal DNAs it vas estimated, that all tested mutants normally contain the modification system analogous to Nae I (Roberts, 1987). Mutant R 8/26 expresses not only complete restriction-modification system mentioned above but also potential second system restricting several actinophages.