Multistage selection of soil actinomycete Streptomyces albus as a producer of antimicrobial substances.

Streptomycetes are known as the producers of various bioactive substances widely used in agriculture and many branches of industry. Different biotechnological methods and approaches are used to increased productivity of streptomycetes. In the present study, S. albus strains were subjected to mutagenesis associated with multistage selection and mutant strain with an increase of 3.5 times bacteriolytic enzyme complex production was obtained. Analysis of cell survival rate, antimicrobial and lytic activity as well as enzyme complex production in Streptomyces exposed to the various mutagen combinations (MNU, UV-irradiation, HNO2) were carried out. Mutant strains were characterized by high bacteriolytic enzyme activity and significant antibiotic activity against Kocuria (Micrococcus) variants and Candida albicans. To estimate genomic changes caused by different mutagens, PCR with primers to short nucleotide repeats was performed and amplicons distinguishing parental and mutant strains were defined. The efficacy of the sequential mutagenic treatment for the hyperproducer obtaining as well as the relationship between the mutagen nature and the genomic variability has been shown. The results obtained in our research can be used and applied to the others Streptomyces species.