Antagonistic activity of marine Streptomyces sp. S073 on pathogenic Vibrio parahaemolyticus.

Marine Streptomyces sp. isolate S073 was shown to have strong antagonistic activity towards the pathogenic Vibrio parahaemolyticus using the agar diffusion method. The antagonistic substance(s) secreted into the supernatant was thermostable and non-proteinaceous in nature. S073 was found to produce carboxylate-type siderophores during most of its life cycle using a chrome azurol S assay. The antagonistic activity of S073 was mostly attributed to its higher ability to compete for iron compared with that of V. parahaemolyticus, as deduced from siderophore quantification. Iron supplementation studies indicated that additional mechanisms besides iron competition were simultaneously involved in governing the observed inhibition. Co-culture analysis indicated that S073, although disadvantaged in growth rate, was still competitive in inhibiting vibrios. The promising potential of S073 development as a biocontrol agent in aquaculture was discussed. [ABSTRACT FROM AUTHOR]