Glidobactin B

Glidobactin deacylating activity was found in a bacterial strain of Pseudomonas sp. Glidobactamine, a key intermediate for acyl analogues of glidobactin, was isolated from the enzymatic degradation products of glidobactins after treatment using a column of fibrous active gel on which the cells of the Pseudomonas strain were immobilized. The chemical structure of glidobactamine was confirmed as the intact peptide moiety of glidobactins by chemical reformation of glidobactin A from glidobactamine and 2,4-dodecadienoic acid which is the constitutive fatty acid of glidobactin A.

Polyangium brachysporum sp. nov. strain ATCC 53080 produces a novel type of antifungal and antitumor antibiotic complex, glidobactins A, B and C. Enhanced production of minor components, glidobactins B and C, was achieved by medium modification. The addition of soybean oil or corn oil, which are rich in unsaturated C18 fatty acids, to the fermentation medium led to an increased production of components B and C. Productivity of component C was selectively enhanced by the addition of oleic acid-rich oils, olive oil and Tween 80 (polyoxyethylene sorbitan mono-oleate). Furthermore, precursing palmitoleate, linoleate and oleate permitted the direct biosynthesis of components A, B and C, respectively. The fermentation with 3% addition of an appropriate oil at initial time provided an optimal production of component B or C.

The structures of new antitumor antibiotics, glidobactins A (Ia), B (Ib) and C (Ic) were elucidated by a combination of chemical and enzymatic degradations and spectral analyses. They have in common a cyclized tripeptide nucleus composed of L-threonine, 4(S)-amino-2(E)-pentenoic acid and erythro-4-hydroxy-L-lysine, and differ from each other in the unsaturated fatty acid moiety attached to the peptide.