Antagonistic effect of Pseudomonas aeruginosa isolates from various ecological niches on Vibrio species pathogenic to crustaceans

Objective:To abrogate pathogenic vibrios in aquaculture by testing the potential of Pseudomonas isolates from fresh water,brackish and marine environments as probiotics.Methods:Antagonistic activity of the compound against 7 Vibrio spp.was performed.Influence of salinity on the production of pyocyanin and the toxicity was done through the compound using brine shrimp lethality assay.Molecular characterization was performed to confirm that the isolates werePseudomonas aeruginosa.Results:Salinity was found to regulate the levels of pyocyanin production,with 5-10 g/L as the optimum.All Pseudomonas isolates grew at salinities ranging from 5 to 70 g/L.Isolates of marine origin produced detectable levels of pyocyanin up to 45 g/L salinity.Brackish and freshwater isolates ceased to produce pyocyanin at salinities above 30 g/L and 20 g/L,respectively.Culture supernatants of all 5 Pseudomonas isolates possessed the ability to restrict the growth of Vibrio spp.and maximum antagonistic effect on Vibrio harveyi was obtained when they were grown at salinities of 5 to 10 g/L.The marine isolate MCCB117,even when grown at a salinity of 45 g/L possessed the ability to inhibit Vibrio spp.Conclusions:Purification and structural elucidation of antagonistic compound were carried out.ideal for application in freshwater,MCCB102 and MCCB103 in brackish water and MCCB117 and The present investigation showed that Pseudomonas aeruginosa MCCB119 would be MCCB118 in marine aquaculture systems as putative probiotics in the management of vibrios.