[Method of isolating spontaneous variants of actinomycete cultures, producers of antibiotics].

The necessity of taking into account the specific characteristics of the colony differentiation for isolation of spontaneous variants of the initial culture with the method of monospore plating was shown on the examples of the geliomycin-producing culture Actinomyces chromogenes var. trienicus 141-18. It was found that the population density of the colonies had a significant effect on the differentiation rate during the subsequent stages and completeness of the culture development. The less was the population density, the longer was the period of the colony complete development. Definite levels of the colony organization (fractionation of morphogenesis) corresponded to different dilutions of the monospore suspension providing definite population densities of the colonies on the plates. On the basis of the data on the colony differentiation compared with the data on the population density effect upon differentiation it was possible to determine without mistake stable variants on the plates at any dilution of the monospore culture, i.e. with any population density of the colony.