Narayanan Gobi

GFP tagged Vibrio parahaemolyticus Dahv2 infection and the protective effects of the probiotic Bacillus licheniformis Dahb1 on the growth, immune and antioxidant responses in Pangasius hypophthalmus

In this study, the pathogenicity of GFP tagged Vibrio parahaemolyticus Dahv2 and the protective effect of the probiotic strain, Bacillus licheniformis Dahb1 was studied on the Asian catfish, Pangasius hypophthalmus. The experiment was carried out for 24 days with three groups and one group served as the control (without treatment). In the first group, P. hypophthalmus was orally infected with 1 mL of GFP tagged V. parahaemolyticus Dahv2 at two different doses (10(5) and 10(7) cfu mL(-1)). In the second group, P. hypophthalmus was orally administrated with 1 ml of the probiotic B. licheniformis Dahb1 at two different doses (10(5) and 10(7) cfu mL(-1)). In the third group, P. hypophthalmus was orally infected first with 1 mL of GFP tagged V. parahaemolyticus Dahv2 followed by the administration of 1 mL of B. licheniformis Dahb1 (combined treatment) at two different doses (10(5) and 10(7) cfu mL(-1)). The growth, immune (myeloperoxidase, respiratory burst, natural complement haemolytic and lysozyme activity) and antioxidant (glutathione-S-transferase, reduced glutathione and total glutathione) responses of P. hypophthalmus were reduced after post infection of GFP tagged V. parahaemolyticus Dahv2 compared to control. However, after administration with the probiotic B. licheniformis Dahb1 at 10(5) cfu mL(-1), P. hypophthalmus showed significant increase in the growth, immune and antioxidant responses compared to 10(7) cfu mL(-1). On the otherhand, the growth, immune and antioxidant responses of P. hypophthalmus infected and administrated with combined GFP tagged Vibrio + Bacillus at 10(5) cfu mL(-1) were relatively higher than that of GFP tagged V. parahaemolyticus Dahv2 and control groups but lower than that of probiotic B. licheniformis Dahb1 groups. The results of the present study conclude that the probiotic B. licheniformis Dahb1 at 10(5) cfu mL(-1) has the potential to protect the P. hypophthalmus against V. parahaemolyticus Dahv2 infection by enhancing the growth, immune and antioxidant responses. The probiotic B. licheniformis Dahb1 would be effectively used in the treatment of aquatic diseases for improvement of aquaculture industry.

Dietary supplementation of probiotic Bacillus licheniformis Dahb1 improves growth performance, mucus and serum immune parameters, antioxidant enzyme activity as well as resistance against Aeromonas hydrophila in tilapia Oreochromis mossambicus

ABSTRACT The present study evaluated the dietary supplementation of probiotic Bacillus licheniformis Dahb1 on the growth performance, immune parameters and antioxidant enzymes activities in serum and mucus as well as resistance against Aeromonas hydrophila in Mozambique tilapia Oreochromis mossambicus. Fish (24±2.5g) were fed separately with three diets, 1) commercial diet (control), 2) diet containing probiotic at 105cfug−1 (D1) and 3) diet containing probiotic at 107cfug−1 (D2) for 4 weeks. Growth performance in term of final weight (FW) specific growth rate (SGR) and feed conversion ratio (FCR), immune parameters of total protein (TP), alkaline phosphatase (ALP), myeloperoxidase (MPO), lysozyme (LYZ), reactive oxygen species (ROS), reactive nitrogen species (RNS) and antioxidant parameters of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in serum and mucus were evaluated after 2nd and 4th weeks. The FW, SGR, and FCR of fish fed with D1 and D2 significantly improved (p<0.05). The activities of ALP, LYZ and MPO in the mucus were significantly higher (p<0.05) in fish that fed D1 and D2. The TP, ROS, RNS, SOD and GPx in the serum were significantly higher (p<0.05) in fish that fed D1 and D2. In addition, the challenge test showed that fish fed D1 and D2 enhanced significantly (p<0.05) the resistance against A. hydrophila (1×107cells ml−1). In conclusion, probiotic B. licheniformis Dahb1 can be applied in diet at 107cfug−1 to improve healthy status and resistance against A. hydrophila in tilapia farming. HIGHLIGHTSBacillus licheniformis Dahb1 could be used as feed additive to O. mossambicus.The growth performance of fish fed with the diet containing B. licheniformis Dahb1 significantly improved.Antioxidant and immune parameters in mucus and serum enhanced in B. licheniformis Dahb1 groups.Dietary supplementation of probiotic improved survival rate of O. mossambicus against A. hydrophila challenge.The optimal dose of dietary supplementation of B. licheniformis Dahb1 was 107cfug−1 diet.

Effect of β-1, 3 glucan binding protein based zinc oxide nanoparticles supplemented diet on immune response and disease resistance in Oreochromis mossambicus against Aeromonas hydrophila

&NA; Recently, several immunostimulants such as &bgr;‐glucan, microbial and plant products have been used as dietary supplements to combat disease outbreaks in aquaculture. The present study investigates the potential of Portunus pelagicus &bgr;‐1, 3 glucan binding protein based zinc oxide nanoparticles (Pp&bgr;‐GBP‐ZnO NPs) supplemented diet on growth, immune response and disease resistance in Mozambique tilapia, Oreochromis mossambicus. The immune‐related protein &bgr;‐GBP was purified from the haemolymph of P. pelagicus using Sephadex G‐100 affinity column chromatography. Pp&bgr;‐GBP‐ZnO NPs was physico‐ chemically characterized and experimental feed was formulated. Fish were separately fed with commercial diet (control‐group I) and Pp&bgr;‐GBP (group II, III, IV), Pp&bgr;‐GBP‐ZnO NPs (group V, VI, VII), chem‐ZnO NPs (VIII, IX, X) mixed diet at the concentration of 0.001%, 0.002% and 0.004% respectively. Triplicate groups of O. mossambicus were fed with experimental diets twice a day for 30 days. Fish receiving Pp&bgr;‐GBP‐ZnO NPs supplemented diet showed a significant increase (P < 0.05) in growth performance. Cellular immune responses (myeloperoxidase activity, lysozyme activity and reactive oxygen species activity) and humoral immune responses (complement activity, antiprotease activity and alkaline phosphatase activity) were evaluated at an interval of 15 days during the feeding trial. Results demonstrate that both cellular and humoral immune responses were substantially increased (P < 0.05) in fish fed with 0.004% of Pp&bgr;‐GBP‐ZnO NPs supplemented diet than others. Antibiofilm potential of Pp&bgr;‐GBP‐ZnO NPs against Aeromonas hydrophila was visualized through confocal laser scanning microscopy (CLSM), which reveals reduction in the preformed biofilm thickness to 10 &mgr;m at the concentration of 50 &mgr;g/ml. Furthermore, after 30 days of feeding trial, fish were challenged with aquatic fish pathogen A. hydrophila (1 × 107 cells ml−1) through intraperitoneal injection. Challenge study displayed a reduced mortality rate in fish fed with diet containing Pp&bgr;‐GBP‐ZnO NPs. Thus our study suggests that dietary supplementation of Pp&bgr;‐GBP‐ZnO NPs at 0.004% may have a potential effect to enhance the immune system and survival of O. mossambicus. Graphical abstract Figure. No caption available. Highlights&bgr;‐ 1, 3 glucan binding protein based zinc oxide nanoparticles (Pp&bgr;‐GBP‐ZnO NPs) were synthesized and characterized.Pp&bgr;‐GBP‐ZnO NPs supplemented diet actively enhances the immune response of Oreochromis mossambicus.Pp&bgr;‐GBP‐ZnO NPs supplemented diet fed fishes exhibit resistance against Aeromonas hydrophila infection.

Bioaccumulation, cytotoxicity and oxidative stress of the acute exposure selenium in Oreochromis mossambicus

Selenium (Se) is an essential trace-element that becomes toxic when present at high concentrations for aquatic organisms. The knowledge about the mechanism of Se toxicity in freshwater ecosystem is still poorly studied. Thus the aim of the present study was to assess the impact of environmentally relevant concentrations of Se toxicity: 5, 10, 25, 50 and 100 µg/L or water only (control) for periods of 96 hour (h) to test for Se accumulation (gill, liver and brain), its effects on enzymatic and non-enzymatic antioxidant defenses (gill and liver), oxidative stress effects on lipid, protein (gill and liver), DNA (liver) and inhibition of AchE (brain) activity were measured in Mozambique tilapia, Oreochromis mossambicus. Our result showed that Se accumulation was observed in the gill, liver and brain tissues of fish exposed to different concentrations and accumulation varied upon different tissues. Enzymatic (SOD, CAT, GPx and GST) and non-enzymatic (GSH and MT) antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione-s-transferase (GST) were significantly increased after 96 h exposure of higher concentrations Se in the gill and liver tissue with the exception of GST activity was significantly inhibited in liver after 96 h exposure of higher concentrations of Se. In contrast, catalase (CAT) activities were inhibited for both tissues of Se exposure at 96 h. Reduced glutathione (GSH) and Metallothionein (MT) levels were increased in the gill and liver tissues after exposure to Se for 96 h. We also observed that Se affected antioxidant defense, increasing oxidative stress indicator of lipid peroxidation (LPO) and protein carbonyl (PCO) in gill and liver tissues of fish exposed to Se for 96 h at the concentration dependent manner. Increased DNA damage scores observed in liver tissue of fish exposed to Se for concentrations dependent manner, indicating potential of Se on fish. We also observed inhibition of acetylcholine esterase (AchE) activity in brain tissue of fish exposed to Se for higher concentrations. The changes in these parameters can be used as suitable biomarkers for monitoring the toxicity of Se in the aquatic environment.

β-1, 3 glucan binding protein based selenium nanowire enhances the immune status of Cyprinus carpio and protection against Aeromonas hydrophila infection

Abstract In the present study, immunoenhancing effect of &bgr;‐1, 3 glucan binding protein based selenium nanowire (Ph&bgr;‐GBP‐SeNWs) in common carp, Cyprinus carpio was assessed. Biological based selenium nanoform was synthesized, using crustacean immune molecule &bgr;‐GBP purified from the haemolymph of Paratelphusa hydrodromus. The morphological property of Ph&bgr;‐GBP‐SeNWs was analyzed through TEM which reveals, the synthesized nanowire exhibits approximately 30–50 nm width with smooth surface. For this current study, fish were fed with experimental diet includes Ph&bgr;‐GBP, sodium selenite, selenomethionine and Ph&bgr;‐GBP‐SeNWs supplemented diet at different concentrations (0.5 mg, 1 mg and 2 mg) for 30 days. The growth performance, cellular and humoral immune responses (myeloperoxidase, reactive oxygen species, alkaline phosphatase and lysozyme activity) and antioxidant enzymes (glutathione peroxidase and catalase activity) in the fish fed with Ph&bgr;‐GBP‐SeNWs supplemented diet were significantly increased in dose‐dependent manner, which was observed at two different interval period (15th and 30th day). Also, Ph&bgr;‐GBP‐SeNWs supplemented diet fed fish gain resistant after challenged with aquatic pathogen Aeromonas hydrophila and the relative survival percentage was increased. Agar disc diffusion and BacLight assay clearly demonstrated the antibacterial property of plasma of fish fed with Ph&bgr;‐GBP‐SeNWs supplemented diet against aquatic pathogen A. hydrophila, Vibrio parahaemolyticus and Vibrio alginolyticus. Moreover, confocal laser scanning microscopic analysis clearly showed that, Ph&bgr;‐GBP‐SeNWs supplemented diet fed fish plasma was more efficient in disrupting the architecture of bacterial colonies and thereby reduced the thickness of biofilm. Thus, the present study indicates that, incorporation of Ph&bgr;‐GBP‐SeNWs in the diet enhances the fish immune responses and disease resistance against aquatic pathogens. Graphical abstract Figure. No Caption available. Highlights&bgr;‐GBP was purified from the Paratelphusa hydrodromus haemolymph.Ph&bgr;‐GBP based selenium nanowires (Ph&bgr;‐GBP SeNWs) were synthesized and characterized.Ph&bgr;‐GBP SeNWs supplemented diet and its impact on immune parameters were studied.