Growth Inhibition of Fish Pathogens by Antagonistic Actinomycetes Isolated from Mangrove Environment

Solvent extrnct~ of 6 strains aClinomycete.<; isolated from mangrove environment were found 10 inhibilthe growth offish bacterial pathogens. filamentou~ and non·filamentou~ fungi. Out of the 104 actinomyceles tested 56% of the isolates exhibited antagonistic effect towards gram-negative bacleria and 35.6% toward<; grnm-positive bacteria. 1be concentrations required to bring about 100% inhibition offilamemoos fungi wa<; 500-7&J ~Ig. in crudeextrnct<;. 1be same concentrotion produced inhibition zone in bacteria ranging from 2mm to IOmm in diameter against various test pathogens. Antibiogrnm of the ·actinomycete5 against test pathogen~ showed two extreme zones (category I and Category X) of inhibition by most of the antagonistic actinomycetes. The results suggest that the crude extract of these antagoni~lic actinomycetes possesses both antibacterial and antifungal properties. lberefore the extract promises to be a potential source of antibiotic.<; against fish bacterial pathogens.