[Electron microscopic study of active and inactive variants of Proactinomyces (Nocardia) mediterranei, a producer of rifamycin B].

Four mutants of Proactinomyces (Nocardia) mediterranei, an organism producing rifamycin B were subjected to electron microscopic investigation. The mutants differed in the biosynthetic activity. The investigation showed correlation between the length of the hyphal fragments of the over-substrate mycelium and the level of the organism activity. The study of the fine structure of the mycelium revealed changes in the structure of the cell wall, character of the nuclear material and hyphae vacuolization.