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Several taxonomically unrelated true fungi produce penicillins,1 and one species of Streptomyces has been reported to yield penicillin N.2 Cephalosporin C (1) has been isolated from only one species of Cephalosporiumf We report here the identification of penicillin N, and isolation and structure elucidation of three new /3-lactam antibiotics of the cephalosporin C type from two species of Streptomyces. Metabolite 2 was produced by a strain of Streptomyces lipmanii NRRL 3584. A new streptomycete species,4 Streptomyces clavuligerus NRRL 3585, afforded antibiotics 3 and 4.The antibiotics present in the broth filtrate were concentrated by carbon and anion exchange resin column chromatography. Final purification was achieved by chromatography on cellulose and silica gel to yield the purified antibiotics. The three antibiotics exhibited some common properties. All had a band at about 1770 cm-1 in the ir spectra, suggesting the presence of a /3-lactam carbonyl group.56 The uv spectra showed absorption maxima at ca. 260 nm, characteristic of the 3-cephem chromophore3•7•8 (Table I). Potentiometric titration revealed the presence of three ionizable groups, and amino acid determination on acid hydrolysates by the Spackman-Stein-Moore method9 yielded about 2 µ /ing of a-aminoadipic acid. An acetyl determination with 2 gave a value (1) A

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