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Nanomycins are new antibiotics produced by the strain OS-3966 which was designated Streptomyces rosa var. notoensis. Nanomycins A and B were isolated from the culture filtrate by extraction with organic solvent and silica gel chromatography. The physical and chemical properties suggest that nanaomycins A and B are quinone-related compounds having the molecular formulae, C16H14O6 and C16H16O7, respectively. Nanaomycins A and B inhibit mainly mycoplasmas, fungi and Gram-positive bacteria. The acute toxicities (LD50, ip) of nanaomycins A and B in mice are 28.2 and 169 mg/kg, respectively.

Evidence is put forward which describes the structure and stereochemistry of new antibiotics, nanaomycins A and B, as I and V, respectively. In order to study biosynthesis and to determine the position of the hydroxyl group in the naphthoquinone moiety, a feeding experiment with 1-13C-acetate was effectively carried out. Nanaomycins A and B were found to be synthesized from acetate via a polyketide by Streptomyces rosa var. notoensis.

A screening method was established for selecting new specific inhibitors of bacterial cell wall peptidoglycan synthesis. In the primary test, culture broths of soil isolates were selected based on relative microbial activity. A culture, to be retained, must be active against Bacillus subtilis and lack activities against Acholeplasma laidlawii. In the secondary test, inhibitors of bacterial cell wall synthesis were identified by their ability to prevent the incorporation of meso-[3H]diaminopimelic acid but not to prevent the incorporation of L-[14C]leucine into the acidinsoluble macromolecular fraction of growing cells of Bacillus sp. ATCC 21206 (Dpm). As the tertiary test, inhibitors with molecular weights under 1, 000 were selected by passage through a Diaflo UM-2 membrane. By this screening procedure, six known antibiotics and one new one were picked out from ten thousand soil isolates.