Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. I. Taxonomy, fermentation, isolation and physico-chemical properties.

A strain of actinomycetes identified as Streptomyces flavidovirens produced new antibiotics, mureidomycins (MRD's) A approximately D, specifically active against Pseudomonas aeruginosa. They were isolated from the culture filtrate by successive column chromatographies such as Amberlite XAD-2 and CG-50, Whatman DE-52 and Toyopearl HW-40. They were amphoteric white powders and soluble in methanol and water. Their molecular weights and molecular formulae in parentheses were 840 (C38H48N8O12S), 842 (C38H50N12S), 897 (C40H51N9O13S) and 899 (C40H53N9O13S), respectively. m-Tyrosine and two unknown substances were detected by amino acid analyses as their common constituents. MRD's A and C contained uracil but MRD's B and D dihydrouracil instead of uracil.