Macbecins I and II, new antitumor antibiotics. I. Producing organism, fermentation and antimicrobial activities.

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Abstract
New antibiotics, macbecins I and II, were found in the culture fluid of an actinomycete, which has the following properties: delayed fragmentation of vegetative mycelia, formation of coremia on solid media, the occurrence of meso-diaminopimelic acid in the cell wall, lysozyme resistance and guanine-cytosine content of 71 .+-. 1 mol%. The organism was designated Nocardia sp. No. C-14919 (N-2001). A marked enhancement of the production of macbecins I and II was observed in cultures containing L-tyrosine. The antibiotics are moderately active against several gram-positive bacteria and fungi. The antibiotics also inhibit the growth of Tetrahymena pyriformis W at 2 .mu.g/ml but show no activity against the regeneration of cilia in partially deciliated Tetrahymena at 10 .mu.g/ml.