Isolation and characterization of new peptide antibiotics, plusbacins A1-A4 and B1-B4

New antibiotics, plusbacins A1-A4 and B1-B4, were isolated from the culture broth of a strain of Pseudomonas sp. These antibiotics were isolated as a complex by column chromatographies on Diaion HP-20 and silica gel, and then separated by HPLC. They are amphoteric in nature. The hydrochlorides are obtained as colorless powders, soluble in methanol and alkaline water. From their physico-chemical properties, these antibiotics are presumed to be acyloctapeptides containing a lactone linkage, and their differences occur in amino acid and fatty acid residues. The antibiotics are active against Gram-positive bacteria in vitro and in vivo.