The generalized transducing phage SV 1 of Streptomvces zienezuelae lysogenizes its host with low efficiency and is therefore temperate. Phage SV2 is also temperate in S. venezuelae, which it lysogenizes more efficiently than S V I . Prophage SV2 is the first example of a u.v.-inducible prophage in Streptomyces. Stable double lysogens able to produce both SV 1 and SV2 and insensitive to each phage have been isolated. The relative efficiencies of plating of S V l and SV2 on four different strains of S. venezuelae indicate that, between them, these strains have four different host specificities. The molecular basis of each host specificity remains to be determined.

Shaken cultures of Strepfomyces wnezueZe ISP5230 in minimal medium with galactose and ammonium sulphate as carbon and nitrogen sources, respectively, showed extensive sporulation after 72 h incubation at 37 OC. The spores formed in these cultures resembled aerial spores in their characteristics. The ability of the spores to witbtand lysozyme treatment was used to monitor the progress of sporulation in cultures and to determine the physiological requirements for sporulation. In media containing ammonium sulphate as the nitrogen source, galactose was the best of six carbon sources tested. With galactose S. venezue2u.e ISP5230 spomlated when supplied with any of several nitrogen sources; however, an excess of nitrogen source was inhibitory. In cultures containing galactose and ammonium sulphate, sporulation was suppressed by a peptone supplement. The onset of sporulation was accompanied by a drop in intracellular GTP content. When decoyinine, an inhibitor of GMP synthase, was added to a medium containing starch and ammonium sulphate, a slight increase in sporulation was seen after 2 d. The suppression of sporulation by peptone in liquid or agar cultures was not reversed by addition of decoyinhe. A hypersporulating mutant of S. uenezue2u.e ISP5230 was altered in its ability to assimilate sugars. In cultures containing glucose the mutant sporulated more profusely than did the wild-type and did not acidify the medium to the same extent. However, the suppressive effect of glucose on sporulation was not merely a secondary result of acid accumulation.

Twelve Streptomyces venezuelae mutants blocked in chloramphenicol biosynthesis were isolated. Two of these (Cm1-1 and Cm1-12) were apparently blocked in the conversion of chorismic acid to p-aminophenylalanine and three (Cm1-4, Cm1-5 and Cm1-8) accumulated p-aminophenylalanine and may have been blocked in the hydroxylation reaction that converted this intermediate to p-aminophenylserine. One mutant (Cm1-2) accumulated D-threo-1-p-nitrophenyl-2-propionamido-1,3-propanediol and D-threo-1-p-nitrophenyl-2-isobutyramido-1,3-propanediol, indicating that chlorination of the alpha-N-acyl group of chloramphenicol was blocked. The remaining six strains did not excrete any detectable chloramphenicol pathway intermediates.

Genetic and biochemical evidence was obtained for lysine catabolism via cadaverine and 8-aminovalerate in both the P-lactam producer Streptomyces clavuligerus and the nonproducer Streptomyces lividans. This pathway is used when lysine is supplied as the sole source of diitrogen for the organism. A second pathway for lysine catabolism is present in S. clavuligerus but not in S. lividans. It leads to oa-aminoadipate, a precursor for ,-lactam biosynthesis. Since it does not allow S. clavuligerus to grow on lysine as the sole nitrogen source, this pathway may be used exclusively to provide a precursor for B-lactam biosynthesis. j8-Lactam producers were unable to grow well on a-amin6adipate as the only nitrogen source, whereas three of seven species not known to produce P-lactam grew well under the same conditions. Lysine E-aminotransferase, the initial enzyme in the ea-aminoadipate pathway for lysine catabolism, was detected in cell extracts only from the ,I-lactam producers. These results suggest that synthesis of a-aminoadipate is exclusively a secondary metabolic trait, present or expressed only in I8-lactam producers, while genes governing the catabolism of a-aminoadipate are present or fully expressed only in ,B-lactam nonproducers.Lysine catabolism in aerobic bacteria is notable for its biochemical diversity. In the genus Pseudomonas, there are four inducible lysine catabolic pathways. Two of these lead to 8-aminovalerate, one pathway initiated by decarboxylation of lysine to cadaverine (5, 18) and the other by a monooxygenase-catalyzed conversion of lysine to 5-aminovaleramide (13, 20). In the remaining pathways, lysine is transaminated either to 1-piperideine-6-carboxylate (5) or to pipecolate (12), both of which may be catabolized to aaminoadipate. In Flavobacterium lutescens, lysine catabolism proceeds through 1-piperideine-6-carboxylate to cx-aminoadipate (16, 17). Romano and Nickerson (14) reported that lysine supported modest growth of Streptomyces fradiae when it was supplied as the sole source of nitrogen and carbon, but they provided no information on the pathway involved. Subsequently, the ca-aminoadipyl side chain of P-lactam antibiotics was found to be derived from lysine, and the first enzyme catalyzing this conversion was identified as lysine E-aminotransferase (10). Association of this enzyme with P-lactam production in cultures of Streptomyces (now Nocardia) lactamdurans and the isolation of mutants blocked in both 1-lactam production and lysine e-aminotransferase (10) suggested that the pathway for P-lactam antibiotic biosynthesis might start from lysine.In this paper, we present biochemical and genetic evidence for the catabolism of lysine via cadaverine in both the P-lactam producer Streptomyces clavuligerus and in Streptomyces lividans, a species not known to produce P-lactam antibiotics. We also provide evidence that the pathway for conversion of lysine to a-aminoadipate is absent from S. lividans, suggesting that this pathway is principally involved in antibiotic production, and show th...

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