Polysaccharide from red seaweed Gracilaria folifera has an interesting functional property of antioxidant activity and prebiotic effect. A feeding trial experiment was directed to examine the effect of probiotic bacteria Bacillus vireti 01 microencapsulated with G. folifera polysaccharide against freshwater prawn M. rosenbergii. Three different feeding trials were conducted for 15 days. The first group contained prawns fed with commercial diet. The second group was comprised of Aeromonas hydrophila challenged prawns fed with commercial feed. The third group consisted of A. hydrophila challenged prawns fed with microencapsulated probiotic-polysaccharide. Survival percentage was significantly decreased in prawns of group2 as compared to that of group1 and group3 prawns (p < 0.0001). The immunological parameters and antioxidant activities (p < 0.001) were found to be increased in group three prawns which were fed with encapsulated probiotic-seaweed polysaccharide and challenged with A. hydrophila as compared to that of group1 and group2. Tissue necrosis, fused lamella, haemocyte infiltration and damage of hepatopancreas lumen and tubule were noted in group2 prawns. There was no histological changes were observed in group3 prawns in which the histological architecture was similar to the control group1. The results suggested that combination of encapsulated probiotic B. vireti 01 and seaweed polysaccharide as dietary feed showed an enhancement of immune response, antioxidant activity and disease resistant of M. rosenbergii against A. hydrophila.

Enhanced biomedical applications of carbon nanotubes (CNTs) have necessitated the need for the fundamental understanding behind their interaction with biomolecules. Carbon nanotube bundles were dispersed with tween 20 to attain individual nanotubes that are active in UV–vis region. Plasmon resonance of dispersions was obtained at 252nm of 4.88eV. FT-Raman bands of dispersions of SWCNTs and MWCNTs at 1346 and 1573cm−1 corresponds to the existence of Disordered and Graphitic band of CNTs after dispersion. XRD revealed crystalline feature of graphitic structures of CNTs. SEM-EDAX showed tubular structures of CNTs along with the existence of lower percentage contents of metal impurities. Hyperchromic effect of BSA–CNT complex suggested the existence of ground state complex between them. Quenching nature of CNTs against the intrinsic fluorescence potential of BSA followed static mechanism. 3D fluorescence spectra of BSA confirmed the possibilities of their binding with CNTs via tryptophan and tyrosine residues, followed by the disturbances to their aromatic environment. Alterations were observed in the amide band position of FTIR spectra of BSA–CNT conjugates. Loss of alpha-helical structures and alteration in the tryptophan position were evidenced with respect to CD spectra. The toxicity profile of pristine and BSA–CNT conjugates were evaluated against Donax faba. On comparison with pristine CNTs, BSA–CNTs conjugates showed higher LC50 dose values. In addition, the histopathology of the tissues, treated with CNT–BSA conjugates has shown decreased effect on the cellular integrity rather than the pristine ones. Hence, the adsorption of biomolecules such as the proteins over CNTs surface could have possible effect on reducing their toxicity profile in nature.

The present study uses two differential extraction methods (sequential, maceration) to identify bioactive compounds present in two seaweeds Gracilaria folifera and Sargassum longifolium. Five different solvents namely Petroleum ether, Dichloromethane, Chloroform, ethanol and water were used. The bioactive compounds present in the extracts showed antioxidant and antibacterial activities against Aeromonas salmonicida. Ethanol and aqueous extracts of these seaweeds were found to have better antibacterial activity against bacterial diseases in fish when compared to the other extracts. Toxicological and in vivo pathogenicity studies were performed with the highest concentration of 250mg/l of extracts. The compounds identified by GC–MS which were found to have antibacterial activity were prepared in the form of a colloidal suspension for oral treatment. The use of algal extracts in aquaculture disease management is a cost effective and eco-friendly approach. These extracts could be used as prophylactics.

Fish diseases caused by Pseudomonas aeruginosa, a known pathogenic organism, is responsible for considerable economic losses in the commercial cultivation of Oreochromis mossambicus (Tilapia). The bacteria were injected into healthy fish through intramuscular injection, oral and immersion challenge. Infection was confirmed by histopathological investigation of the infected organs. Lime nanoemulsion was prepared and the effectiveness of the nanoemulsion was studied both in vitro and in vivo by well diffusion assay and in vivo in the artificially infected fish. Results showed that the lime nanoemulsion was effective against the P. aeruginosa infection in O. mossambicus both in vitro and in vivo.

Antioxidants are increasingly being recommended because they act directly on oxidative processes and may prevent diseases and problems associated with disease control and aging. Therefore, there is a constant search for antioxidants from natural sources for the isolation of antioxidant biomolecules. Seaweeds are an excellent source of natural antioxidant bioactive compounds which can be used as dietary supplements or as antioxidants in controlling bacterial infection in aquaculture farms as well as in the food industry. A great deal of effort has therefore focused on using available techniques to identify natural antioxidants from seaweeds.The aim of the present study was to analyse the bioactive compounds extracted from ethanol extract of the seaweed Chaetomorpha antennina by GC-MS study and to evaluate its antioxidant and antibacterial activities for controlling bacterial infection in shrimp pathogens through immersion and intramuscular infection study. The antioxidant activity of the selected seaweed was estimated in order to evaluate the efficiency of its ethanol extract since this will help in finding novel bioactive compounds with antioxidant & radical scavenging properties, which in turn can reveal the unexploited properties of this seaweed which could be used in the food and pharmaceutical industry. (C) 2014 Elsevier B.V. All rights reserved.

Aquaculture health management demands a constant growth in the production by stabilizing economic loss and implementing various natural plant-based bio products for treating pathogenic bacteria. Pathogenic effects of the Citrobacter freundii isolated from fingerlings of Tilapia collected from a fish farm showed symptoms like tail necrosis, septicemia, hemorrhage, and reddening of the body. Antibacterial activity of C. freundii was tested against various medicinal plants. Of the three plants screened, Azadirachta indica (Neem) showed good antibacterial activity against C. freundii. The present study revealed that A. indica plant extract at a concentration of 150mg/l in vivo can be used as an alternative to antibiotics for treating this bacterial infection. The use of medicinal plant extract-mediated treatment was found to be very effective in controlling this bacterial infection.

Clarias batrachus (Linn) is a species of catfish of the family claridae. Pathogenecity of Aeromonas salmonicida was studied in healthy fish. The inoculum was injected into healthy fingerlings through intramuscular injection and immersion challenge. Histopathological investigation of the infected organs was also studied. The bacterial infection was treated using neem nanoemulsion by in vitro and in vivo analysis and was found to be effective.