Antimicrobial activity among Pseudomonas and related strains of mineral water origin

Siderophore production in 382 Pseudomonas and related strains of mineral water origin were screened and the antimicrobial activities of 158 of these tested against nine target organisms of health significance. Presence of siderophores could be detected in 54.4% and the majority of strains tested (91.2%) inhibited at least one of the nine target strains. Staphylococcus, Escherichia coli and Aeromonas hydrophila were particularly sensitive. Addition of iron eliminated the inhibitory activity in 96.7% of cases; the antagonistic effect should be largely determined by siderophore-mediated competition for iron. Most of the inhibitory strains produced siderophores, whereas the non-inhibitory strains did not. Few strains also produced bacteriocins showing activity against Pseudomonas aeruginosa and Aer. hydrophila. Strains isolated from mineral water have a broad antibacterial potential.