Abstract
Three types of blocked mutants were isolated from Streptomyces griseus subsp. cryophilus, which produces ight 5, 6-cis carbapenem antibiotics and penicillin N. The type I mutant was defective in producing dimethylated compounds at the C-8 position (C-19393 H2 and S2). The type II mutant, derived from the type I mutant, could not produce compounds with a sulfoxidated side chain at the C-2 position (C-19393 E5 and MM 4550 as well as C-19393 H2 and S 2). The type III mutant accumulated only epithienamycin A and MM 17880 in large amounts. On the other hand, 8-dimethylated compounds with a saturated or deoxidized side chain at the C-2 position could not be detected in culture filtrates of the parent or these mutants. Based on the results, we propose a possible biosynthetic pathway for 5, 6-cis carbapenem antibiotics.
