Abstract: Antibiotic A-2315 mixture, comprising microbiologically active, structurally related factors A, B, and C, produced by culturing Actinoplanes philippinensis NRRL 5462 under submerged aerobic fermentation conditions. Individual factors A, B, and C are separated and isolated by chromatographic procedures. The A-2315 antibiotics are useful in controlling the growth of cariogenic organisms, in promoting the growth of chickens, and in increasing feed-utilization efficiency in ruminants.

Abstract: A process for producing antibiotic nebramycin II, a component antibiotic of the multifactored antibiotic complex nebramycin, and nebramycin VII by culturing Streptomyces tenebrarius NRRL 3816, mutant strain ex Streptomyces tenebrarius ATCC 17920 in an aqueous nutrient culture medium under aerobic fermentation conditions. Nebramycin II is recovered from the filtered fermentation broth by chromatography over a cationic exchange resin and is separated from the newly discovered co-produced minor factor, nebramycin VII, by further chromatography over a cationic exchange resin.