title: Isolation of the L-phase variant from toxigenic Corynebacterium diphtheriae C7(beta).
abstract: The L-phase variant was isolated from lysogenic strain C7(beta) of Corynebacterium diphtheriae by the penicillin disk tecnnique on an agar medium containing 3.7% brain heart infusion, 3% NaCl, 1.25% Grycine, 1% Noble agar, and 10% horse serum. The L-phase formed a "fried egg" colony; it was resistant to antibiotics that inhibit biosynthesis of bacterial cell walls but was susceptible to antibiotics that act on the protein-synthesizing system. After several transfers of the L-phase initially isolated, the L-phase of strain C7(beta) became stable, forming a typical L-phase colony on the agar even without penicillin. The L-phase variant retained lysogenicity and toxigenicity. The toxin production by this L-phase variant was, like that by the bacterial phase, inhibited by excess iron.
mesh_terms: D001427:Bacterial Toxins / Q000096:biosynthesis*; D002473:Cell Wall; D003353:Corynebacterium diphtheriae / Q000235:genetics / Q000302:isolation & purification*; D003470:Culture Media; D014644:Genetic Variation; D008242:Lysogeny; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology; D010641:Phenotype
chemical_list: D001427:Bacterial Toxins; D003470:Culture Media; D010406:Penicillins