SF-1902 is a solvent-soluble, neutral antibiotic produced by Streptomyces hygroscopicus SF-1902, which shows antibacterial activity only against Gram-negative bacteria. HPLC analysis of the sample seemingly homogeneous on TLC disclosed several components, and the major component SF-1902 was identified as globomycin by direct comparison including ORD curves. The minor component SF-1902 A5 was obtained as homogeneous crystals. Its physico-chemical properties were determined: m.p. 113~117°C, [α]²⁰ᴰ -16° (c 0.7, CHCl₃), molecular formula C₃₄H₆₁N₅O₉. Acid hydrolysis revealed it contained the same amino acids (L-allothreonine, L-serine, glycine, N-methylleucine, L-allo-isoleucine) as globomycin. Structural studies using CMR, GC-MS (fatty acid moiety identified as threo-3-hydroxy-2-methylundecanoic acid), and mass spectrometry of permethylated derivatives indicated that SF-1902 A5 is a homologue of globomycin, with the fatty acid chain having two more methylene units than globomycin and the lactone ring formation site identical to that of globomycin. SF-1902 A5 exhibits stronger antibacterial activity than globomycin.