Dendrilla nigra, a marine sponge, as potential source of antibacterial substances for managing shrimp diseases

Secondary metabolites of marine sponge Dendrilla nigra were tested for determining the efficacy of controlling shrimp bacterial pathogens. Based on the exploratory experiments, the chosen dose of D. nigra (500 mg/kg of shrimp) was used for pilot experiment. The percent relative protection (PRP) of shrimps treated with Dendrilla feed and challenged with various concentrations of bacterial pathogen was evaluated. Dendrilla feed elicited complete protection (100% survival) against the most common shrimp pathogens such as luminescent Vibrio harveyi and Vibrio alginolyticus. Results of combined bacterial challenge indicated that Dendrilla was a broad spectrum vibriostatic agent. Invariably, the survival of treated shrimp against the bacterial infection was significant at p<0.01 level. Based on the present findings, it could be inferred that the secondary metabolites of D. nigra form an excellent source for developing potent antibacterial agents to combat bacterial diseases of shrimp and replace the conventional antibiotics. (C) 2004 Elsevier B.V. All rights reserved.