[Experience with long-term preservation of international-standard cultures of Actinomycetes].

The results of the study on long-term maintenance (1-12 years) of 453 reference cultures of actinomycetes are presented. The cultures were maintained with the following methods: lyophilization, soil cultures and periodical passages on agarized nutrient media. Lyophilization was most efficient for storage of the majority of the cultures: 346 strains (77.4 per cent) preserved high viability over the observation period of 11-12 years. Lyophilization appeared less favourable for the cultures with low sporulation. The efficacy of the method of soil cultures on long-term storage of the whorl actinomycetes was low: 88 per cent of Streptoverticillium lost their viability within 1-2 years. However, this method was valuable for stabilization of the taxonomic features of streptomycetes. The maintenance of the actinomycetes by regular passages on agarized media every 6 months resulted in the changing of the cultural and morphological features in a number of the strains.