The biosynthetic gene cluster governing production of anti-infective marformycins was identified from deep sea-derived Streptomyces drozdowiczii SCSIO 10141. The putative mfn gene cluster (45 kb, 20 orfs) was found to encode six NRPSs and related proteins for cyclodepsipeptide core construction (mfnCDEFKL), a methionyl-tRNA formyltransferase (mfnA), a SAM-dependent methyltransferase (mfnG), and a cytochrome P450 monooxygenase for piperazic acid moiety hydroxylation (mfnN); notably, only MfnN uses an intact cyclodepsipeptide intermediate as its substrate.