TLC of ethyl acetate extracts from 200-ml culture supernatants of S. ambofaciens strains. Lanes 1 to 4, spiramycin standards (Sigma) (1, 0.125 mg; 2, 0.25 mg; 3, 0.065 mg; 4, 0.5 mg); lanes 5 and 8, RP181110 extracts; lanes 6 and 9, NSA205 extracts; lanes 7, 10, and 11, NSA228 extracts.