Control of bacterial pathogens, associated with fish diseases, by antagonistic marine actinomycetes isolated from marine sediments

Actinomycetes were isolated from different marine samples collected from various stations along the Tuticorin coast. About 133 cultures of actinomycetes were isolated from 129 marine samples. Of the 104 isolates of actinomycetes screened for their inhibitory activity against the bacterial pathogens associated with fish diseases viz. Aeromonas hydrophila, A. sobria and Edwardsiella tarda, 77 isolates were found to be inhibitory to at least one of the pathogens. The highest incidence of inhibitory isolates was from the sediment samples. All the isolates of antagonistic marine actinomycetes were identified to be Streptomyces. The findings suggest that the antagonistic marine Streptomyces isolates or the antibacterial substances produced by them could be used as antibiotics, which might have a future application in aquaculture systems.