SIDEROPHORE PATTERN OF FISH-PATHOGENIC VIBRIO-ANGUILLARUM, AEROMONAS SPP AND PSEUDOMONAS SPP FROM THE GERMAN BALTIC COAST

A total of 355 strains of fish-pathogenic bacteria, including Vibrio anguillarum, Aeromonas hydrophila, A. caviae, Pseudomonas fluorescens and P. putida, were examined for the presence of hydroxamate- or phenolate-type siderophores. These strains were isolated from diseased rainbow trout, Oncorhynchus mykiss (Walbaum), from fish farms in the Baltic Sea off the coast of the former German Democratic Republic. The production of siderophores was demonstrated in bioassays and siderophore-pattern analysed using several indicator strains. All strains tested grew under conditions of iron limitation. The strains of Vibrionaceae produced at least a hydroxamate-type siderophore detected by the bioassay with A. flavescens JG-9. Only a few V. anguillarum, but 50% of A. hydrophila produced a phenolate-type siderophore. Seventy percent of V. anguillarum, 33% of A. hydrophila, 40% of A. caviae, 53% of P. fluorescens and 50% of P. putida promoted the growth of the indicator strain S. typhimurium SR 1001, which can use iron by 2,3-dihydroxybenzoic acid. The pseudomonads tested produced either hydroxamate- or phenolate-type siderophores, or both.