Bisucaberin -: A dihydroxamate siderophore isolated from Vibrio salmonicida, an important pathogen of farmed Atlantic salmon (Salmo salar)

A siderophore of the bacterial fish pathogen, Vibrio salmonicida, was isolated from low-iron culture supernatant and structurally characterized as bisucaberin by FTICR- and FAB-MS, NMR and GC-MS analysis of the hydrolysis products. Although the cyclic dihydroxamate bisucaberin has previously been isolated from a marine bacterium, Alteromonas haloplanktis, its involvement in cold-water vibriosis of Atlantic salmon (Salmon salar) is novel. Bisucaberin production in iron-limited media was highest at temperatures around and below 10 degreesC, correlating well with temperatures at which outbreaks of cold-water vibriosis occur. Due to the very high stability constant of K = 32.2, bisucaberin is a most efficient iron scavenger which may contribute to the virulence of V. salmonicida in Atlantic salmon.