[Genetic control of Actinomycetes resistance to antibiotics].

The results of studies on genetic control of resistance to antibiotics in Streptomyces strains are discussed. Cloning and sequence analysis of resistance genes yield information concerning their expression in homo- and heterologous systems, allow analysis of signal sequences responsible for initiation of transcription and translation. Cloning of genes coding for resistance to neomycin,viomycin, thiostrepton in Streptomyces and Bac. licheniformis ermD gene made them convenient selective markers for constructing vector molecules, useful for identification of homology regions in S. fradiae aph gene and TnS of E. coli; the site homologous to ermD gene has been thus revealed in S. erythreus chromosome. Possibilities of the studies aimed at elucidation of instability of many actinomycete characters using determinants of natural multiple resistance to antibiotics as a model are demonstrated. It has been shown that genetic instability is not related to the loss of plasmids and is associated with genes having chromosomal location. Simultaneous high frequency loss of a number of resistance characters determined by non-linked genes suggests the participation in gene activity regulation of actinomycete genome rearrangements. This is confirmed by evidence for such rearrangements found in strains with mutant phenotypes, including deletions in tyrosinase and streptomycin phosphotransferase genes in Mel- and StrS strains of S. reticuli and S. glaucescens.