[Dynamics of the accumulation of adifferentiated variants in a submerged culture of Streptomyces roseoflavus var. roseofungini].

When Streptomyces roseoflavus var. roseofungini is grown as a submerged culture in a chemically defined medium with stirring, it yields a number of variants in which the capacity to form the aerial mycelium is disturbed. Inoculations of the submerged mycelium of different age into a solid medium give rise to both "tomentose" variants (TV) with the aerial mycelium and "naked" variants (NV) lacking the aerial mycelium. The latter variants comprise Nocardia-like variants (NLV) with the fragmenting mycelium. The following change in the variants occurs in the inoculations of the submerged mycelium in the course of the cultural growth: TV leads to NV leads to NLV or (more rarely) TV leads to NLV. The dynamics of accumulation of the variants depends, to a considerable extent, on the source of carbon in the medium: NLV first appear on the medium containing fructose; NV are detected first on the medium with glucose; NV are rarely found on the medium with mannitol. In aged cultures, the number of NLV can reach 80--90%, the content of TV is 20--10%, and NV are absent. The above results suggest that the formation of NLV from S. roseoflavus var. roseofungini is the result of stepwise selection.