Bacillus subtilis SSE4 produces subtulene A, a new lipopeptide antibiotic possessing an unusual C15 unsaturated β-amino acid

Subtulene A, a new cyclic lipopeptide, was isolated from the culture broth of Bacillus subtilis SSE4. This antibiotic compound contained the seven common α-amino acids, l-Asn-1, d-Tyr-2, d-Asn-3, l-Gln-4, l-Pro-5, d-Asn-6, l-Ser-7 and the unique β-amino acid-8 present in the iturin family. 1D and 2D NMR, as well as MS analyses, identified the β-amino acid as 3-amino-13-methyltetradec-8-enoic acid, an Iso C15 long chain β-amino acid. B. subtilis SSE4 was also found to produce iturin A. B. subtilis SSE4 culture filtrate exhibited both antifungal and antibacterial activities.