Presence of high-affinity iron uptake systems in fish-isolated and environmental strains of Vibrio anguillarum serotype O3.

This work describes the presence of high-affinity iron uptake systems in Vibrio anguillarum serotype O3 strains (subgroups A and B), isolated from diseased fish and environmental samples, as well as the presumptive effect of iron on their virulence. All strains demonstrated an ability to grow under iron-limiting conditions, production of catechol-type siderophores and synthesis of iron-regulated outer membrane proteins. However, clear differences were found depending on the isolation source, suggesting a more efficient iron uptake system in fish-isolated strains. Comparing the iron-regulated outer membrane protein profiles with those described for O1 and O2 serotypes, we found a protein which is specific for serotype O3, and another one that allows the differentiation of serotype O3 fish isolates from environmental strains. Moreover, only the strains showing this protein increased their virulence when iron was added to the inoculum in pathogenicity assays.