Figure 1.

Erythromycin production by S. erythraea NRRL2338 and derivative rif mutants on R3/1 or YS agar media. (A-B) Strains were grown for 7 days on R3/1 (A) or YS (B) agar media and antibiotic production was evaluated by microbiological assays. Data are shown as mean ± standard deviation of triplicate samples in representative experiments. Similar results were obtained in three independent experiments. (C) Pictures of S. erythraea NRRL2338 and rif derivatives rif1 and rif6 after 7 days growth on R3/1 solid medium. Note in rif6 the severe defect in aerial mycelium and spore formation.