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 antibiotic

Shrimp disease management using bioactive marine secondary metabolites: an ecofriendly approach

Vibriosis caused by opportunistic and secondary bacterial pathogens is still a serious disease problem in aquaculture of the black tiger shrimp Panaeus monodon. Attempts were made for controlling shrimp bacterial diseases using marine Secondary Metabolites (MSMs). Findings indicated that the MSMs of seaweed Ulva fasciata and sponge Dendrilla nigra are effective for controlling shrimp bacterial pathogen

Methods for the rapid diagnosis and control of bacterial diseases in shellfishes and finfishes

The culture of finfish and shellfish are often threatened by disease causing bacteria. At times it is difficult to distinguish between infection with a pathogen and disease that may result from such infections. In addition, the stressed animals (physiological or environmental) are easily predisposed to encounter bacterial infections as well as diseases

Immunomodulatory potential of marine secondary metabolites against bacterial diseases of shrimp

Shrimp disease management using bioactive marine secondary metabolites (MSMs) was developed as a package of practice for the sustainable shrimp farming. Therefore, the effect of MSMs on the host defense factors of shrimp was evaluated in the present study. Findings indicated that Ulva diet significantly increase the defense factors such as haemogram, agglutination index, phagocytic rate, bacterial clearance and serum bactericidal activity of treated shrimps over the control group. Based on the gut bacterial load, Ulva diet was considered as proactive drug whereas Dendrilla diet was determined as a curative agent

Pathogenicity, antibiogram and biochemical characteristics of Luminescent Vibrio harveyi, associated with 'Black Shell Disease' of Penaeus monodon

Bacterial isolation was made from shrimps Penaeus monodon showing characteristic external symptoms of 'black shell disease' from shrimp farms located in southeast coast of India. The isolates were screened on TeBS agar plates and 0/129 for the selective isolation of Vibrio sp. Based on the morphological, biochemical and physiological characteristics, the isolate (RJM5) was characterized as luminescent Vibrio harveyi." Antibiogram of V. Imrueyi indicated that it was highly sensitive to chloramphenicol. ciprofloxacin, nalidixic acid and streptomycin. The pathogenicity studies confirmed that the isolate (V.harveyi) was moderately virulent

Bottle-nose dolphin stranded at Kovalam in Kerala

On 5th September 1998, an Indian bottle-nose dolphin {Tursiops truncatus aduncus Ehrenberg. 1833) was washed ashore at Ashoka beach in Kovalam

Antifouling activity of bioactive substances extracted from Holothuria scabra

Methanol extract of Holothuria scabra was tested for antifouling activity using mollusc foot adherence bioassay'. It was found that the secondary metabolites of H. scabra effectively prevented foot adherence of P. vulgata at various concentrations. Based on the present findings it could be inferred that the bioassay guided purification and fractionation may give forth potent novel antifouling compounds

Biopotentials of Ulva fasciata and Hypnea musciformis collected from the peninsular coast of India

The secondary metabolites of seaweed Ulva fasciata and Hypnea musciformis,collected form southeast and southwest coast of India. were tested for biotoxicity potential. Both species bowed potent activity in antibacterial, brine shrimp cytotoxicity, larvicidal, antifouling and ichthyotoxicity assays

Biopotentials of secondary metabolites isolated from marine sponges

The secondary metabolites of three sponges collected as bycatch in the fishing nets were explored for biological potencies. The sponge Dendrilla nigra exhibited wider biological activity. It showed potent activity in antibacterial, brineshrimp cytotoxicity, larvicidal, antifouling and ichthyotoxic assays. One of the well-studied cytotoxic sponge Axinellu donnani was least active in brineshrimp cytotoxicity assay. The secondary metabolites of Clathria gorgonoides were highly cytotoxic albeit it showed least activity in other bioassays. Based on the present findings, it could be inferred that the bioassay-guided fractionation and purification of D. nigra may come up with potent bioactive drug

Vibrio alginolyticus associated with white spot disease of Penaeus monodon

In February 2000, white spot disease outbreaks occurred among cultured Penaeus monodon in extensive shrimp farms on the southwest coast of India. Bacteria were isolated from infected shrimp that showed reddish body coloration and white spots in the cuticle. The isolates were screened on thiosulfate citrate bile salt sucrose (TCBS) agar plates for the selection of Vibrio species. The primary isolate (QS7) was characterized as V alginolyticus based on morphological, biochemical and physiological characteristics. Antibiotic sensitivity tests of QS7 indicated that the isolate was highly sensitive to chloramphenicol, ciprofloxacin, nalidixic acid and streptomycin. Pathogenicity tests confirmed that the isolate was virulent for P. monodon. Based on the lethal dose (LD,,) value (5 x 10"fu per shrimp), it was inferred that shrimp weakened by white spot syndrome virus would succumb to secondary infection by QS