A new antitumor antibiotic is produced in fermentation liquors of Streptomyces zelensis sp.n. The antibiotic is biologically active at extremely low concentrations. At 40 pg/ml, it inhibited 90% of the growth of L1210 cells in culture in tube dilution assays. The minimal inhibitory concentrations against Gram-positive bacteria is between 1-10 ng/ml, while these values for Gram-negative bacteria and fungi are mostly under 1 jig/ml. A microbiological assay with Bacillus subtilis can detect concentrations of I-2 ng/ml. A new antitumor antibiotic, CC-1065, was discovered in our laboratories''. It was isolated from fermentation liquors of a new species of Streptomyces which was designated Streptomyces zelensis DIETZ and Li sp. n. (UCH-5923). This communication describes the production of the drug, the taxonomic study of the producing microorganism, the in vitro activity, and the microbiological assay. The methods of isolation and evaluation against experimental animal tumors will be described in separate communications.

A new variety of Streptomyces hygroscopicus was isolated from a Kalamazoo soil. This isolate is described and identified as var. geldanus. When fermented in preferential media it produces geldanamycin, nigericin, nocardamine, and a libanamycin-like activity. Fermentation conditions, chromatographic separation, and antimicrobial spectra of the antibiotics are given. Four types of antibiotics are produced in submerged culture by S. hygroscopicus var. geldanusl> when the culture is fermented in different media. These antibiotics are geldanamycin, nigericin, nocardamine and a libanamycin-like activity. The taxonomy of the producing actinomycete is given together with the fermentation conditions, paper chromatographic separation of the antibiotics formed and their respective antimicrobial spectra. Materials and Methods Culture An actinomycete isolated from a Kalamazoo soil was characterized as Streptomyces hygroscopicus var. geldanus var. nova (UC 5208).

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A new antimetabolite antibiotic, U-42,126, was discovered by use of a specific in vitro screen. U-42,126 was produced by the fermentation of Streptomyces sviceus . Its antimicrobial activity in vitro was limited to fungi. Certain bacteria were inhibited only when cultivated in completely synthetic media. U-42,126 was active in vivo against L1210 leukemia in mice.

Lomofungin is a new antimicrobial agent obtained from the culture broth of Sireptomyces lomondensis sp. n. UC-5022. Lomofungin is an acidic, olive-yellow, crystalline compound which inhibits, in vitro, a variety of pathogenic fungi, yeasts, and gram-positive and gram-negative bacteria. Streptomyces lomondensis sp. n. produces a new antibiotic designated lomofungin [referred to in U.S. Patent 3,359,165 as lomondomycin (U-24,792)]. Bergy (unpublished data) characterized lomofungin as an acidic, olive-yellow, crystalline compound with the molecular formula C15H1oN206 and a molecular weight of 314. The compound is soluble in dimethyl formamide, alkaline water, acidic acetone, and acidic methyl ethyl ketone. It is only slightly soluble in water, methanol, cyclohexane, acetone, ether, and ethyl acetate. Lomofungin does not melt below 320 C. This paper describes the organism, the fermentation conditions, the paper chromatogram characterization, and some of the biological properties of the antibiotic. MATERIALS AND METHODS Culture. S. lomondensis was characterized by the methods cited by Dietz (2).