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Sixty five cultures of Actinomadura were isolated from samples of different soils. The study of their antibiotic activity on liquid nutrient media showed that 49 of them were active against gram-postive bacteria. The antibiotics isolated fromsome cultures of Am. carminata, Am. rubra, Am. coerulea and Am. luteofluorescens had antitumor effect in experiments on animals.

Stroptomyces strains INA T-511 and INA 3946 were isolated from 2 different soil samples. Both the strains produced an antibiotic of the group of alpha-hydroxyketopentaenes. The antibiotic was active against gram-positive bacteria, yeasts and fungi belonging to Penicillium. In addition, the strains produced a pigment antibiotic of the prodigiosin type and a pigment identified as ferroverdin. The study of the cultural and morphological features and the natural variation of the strains has shown that they belong to a new species, designated as Streptomyces variegatus sp. nov. Sveshnikova et Timuk.

The type cultures of four Actinomadura species (A. africana, A. coeruleofusca, A. flava, A. longispora) were studied and compared with the type culture belonging to the genus Nocardiopsis. In their morphological properties and in the composition of the cell wall, these cultures were shown to be closer to the genus Nocardiopsis Meyer 1976 rather than to the genus Actinomadura Lechevalier et Lechevalier 1970. Basing on these data, the species have been transferred to the genus Nocardiopsis.

A culture of a new species Streptomyces virens was isolated from a soil sample. It produced an antibiotic designated as virenomycin. The antibiotic was mainly synthesized in the mycelium. Only insignificant amounts of it were found in the culture fluid. The optimal nutrient medium for production of virenomycin contained glycerol, soybean meal, ammonium sulphate, sodium chloride and calcium carbonate. Crystalline virenomycin had a comparatively low antitumor activity and narrow spectrum.

Eremomycin, a novel antibiotic belonging to the group of cyclic glycopeptides is produced by an actinomycete designated INA-238. Biosynthesis, isolation, physico-chemical and biological properties of the antibiotic are described. Eremomycin is shown to be close to vancomycin. However, by its chromatographic and electrophoretic mobility, presence of chlorine in the antibiotic molecule and optic characteristics eremomycin differs from vancomycin. Eremomycin is less toxic than vancomycin whereas its chemotherapeutic activity in treatment of infections caused by gram-positive organisms is higher.

A culture of a new actinomycetous species, Nocardiopsis syrinage was isolated from a soil sample. The antibiotic produced by it was named nocamycin. It accumulated in the culture fluid on cultivation of the organism in a nutrient medium containing soybean meal, glycerin, sodium chloride and calcium carbonate. Crystalline nocamycin had an antitumor effect. In inhibited by 72--73 per cent the development of an intraperitoneally implanted lymphadenosis of strain NK/LI in mice.

A new variety of Actinoplanes, named Actinoplanes ianthinogenes subsp. octamycini Gause et Svechnikova is described. It produces an antibiotic complex consisting of purpuromycin and a new antibiotic belonging to the group of polyens, i. e. octamycin. Maximum accumulation of the above antibiotics in the mycelium was observed in the soybean-glycerol medium.