Dibyendu Kamilya

Effects of potential probiotic Bacillus amyloliquifaciens FPTB16 on systemic and cutaneous mucosal immune responses and disease resistance of catla (Catla catla)

Effects of dietary administration of Bacillus amyloliquefaciens FPTB16 on systemic and mucosal immunity and disease resistance of catla (Catla catla) against Edwardsiella tarda infection were evaluated in the present study. The laboratory maintained B. amyloliquefaciens was used to study antagonistic activity against fish pathogenic bacteria by agar well diffusion assay. Healthy catla were challenged by this bacterium for determination of its safety. For preparation of probiotic supplemented diet, the bacteria were added to the basal diet (control) at three different inclusion levels i.e., 1 × 10(9), 1 × 10(8) and 1 × 10(7) CFU/g diet. Fish (weight 25-30 g) were fed with these diets and various immune parameters and disease resistance study were conducted at 4 weeks and 8 weeks post-feeding. The bacterial antagonism study showed inhibition zone against E. tarda, Aeromonas hydrophila, Vibrio parahaemolyticus and V. harveyi. B. amyloliquefaciens was harmless to catla as neither mortalities nor morbidities were observed after the challenge. Study of different systemic and mucosal immunological parameters viz. superoxide anion production and nitric oxide production, myeloperoxidase content, lysozyme activity and total protein content showed significant enhancement (p < 0.05) in fish fed with 10(8) and 10(9) CFU/g B. amyloliquefaciens at both time points with the highest values observed in case of 10(9) CFU/g. For fish fed with 10(7) CFU/g B. amyloliquefaciens, all the parameters showed significant enhancement (p < 0.05) at both time points except the lysozyme activity of serum at 8 weeks. Diet containing 10(8) and 10(9) CFU/g B. amyloliquefaciens significantly enhanced (p < 0.05) the resistance of catla against bacterial challenge at both time points. These results collectively suggest that B. amyloliquefaciens is a potential probiotic species and can be used in aquaculture to improve health status and disease resistance with an optimal dietary supplementation of 10(9) CFU/g.

Epizootic ulcerative syndrome (EUS) in fish: history and current status of understanding

Epizootic ulcerative syndrome (EUS) is one of the most important diseases affecting more than 100 species of wild and cultured finfish. EUS was first reported in farmed ayu (Plecoglossus altivelis) from Japan in 1971 and has since then spread across different countries of four continents including Asia, Australia, North America and Africa. The spread of the disease, especially in Asia–Pacific region and Africa has led to substantial damage to the fish resources and livelihood of the fish farmers. No reports are available confirming the outbreak of the disease from Europe and South America. The latest outbreak of EUS has been reported from Canada in a new susceptible species brown bullhead, Ameiurus nebulosus. It seems that the disease has potential to spread further, owing to the epizootic nature of the disease and broad susceptible host range. Considering the global importance of this disease, this review provides the current status of understanding about the etiology, process of diseases development, species affected, diagnostic methods as well as control and preventive measures, in light of the historical developments in those areas.

In vitro immunopathogenesis of Edwardsiella tarda in catla Catla catla (Hamilton).

Immunopathogenesis of Edwardsiella tarda in Catla (Catla catla) was evaluated by in vitro interaction of catla head kidney (HK) phagocytes with the bacterium. Interactions of E. tarda with catla HK phagocytes were studied by light microscopy as well as by phagocytosis, intracellular replication, superoxide anion and nitric oxide production assays. Both opsonised and non-opsonized bacteria could adhere to, survive and replicate within phagocytes. Furthermore, there was no significant alteration in superoxide anion production by phagocytes when infected with E. tarda, indicating that they were able to avoid and/or resist reactive oxygen species mediated killing by the phagocytes. Enhancement of nitric oxide production indicated its possible involvement as inflammation mediator to facilitate pathogenesis. The results suggest the fact that E. tarda strain has the ability to resist phagocyte mediated killing, thereby proliferating within the host and causing infection.

Paraprobiotic preparation from Bacillus amyloliquefaciens FPTB16 modulates immune response and immune relevant gene expression in Catla catla (Hamilton, 1822)

Abstract The present study evaluated the paraprobiotic effect of heat‐inactivated Bacillus amyloliquefaciens FPTB16 on immunological response and immune relevant gene expression in catla (Catla catla). Heat inactivation of viable cells of B. amyloliquefaciens was done at 60 °C for 2 h. For preparation of paraprobiotic supplemented diet, the heat‐inactivated bacteria were added to the basal diet (control) at three different inclusion levels i.e., 107, 108 and 109 cells g−1 diet. Fish (25.98 ± 2.57 g) were fed with these diets and various immune responses and immune relevant gene expressions were measured after 4 weeks of feeding. Biochemical parameters were also measured along with the immunological responses. Immunological parameters viz. oxygen radical production, serum lysozyme activity and total serum protein content showed significant enhancement (p < 0.05) in fish fed with 108 and 109 cells g−1 diet. Significant enhancement in myeloperoxidase activity was observed in all the dietary groups compared to control. Alkaline phosphatase activity showed significant enhancement (p < 0.05) in fish fed with 107 and 108 cells g−1 diet. Biochemical parameters viz. GPT, GOT and glucose content did not show any significant difference in any of the dietary groups. Immune relevant genes viz. IL‐1&bgr;, TNF‐&agr;, C3 and iNOS showed significantly higher expression in either liver or head‐kidney tissues in most of the cases. However, IFN‐&ggr; expression showed a down‐regulation pattern in both the tissues. In conclusion, the dietary supplementation of heat‐inactivated B. amyloliquefaciens enhanced the immunity of catla, particularly at 108 cells g−1 diet. The results collectively suggest the paraprobiotic applicability of B. amyloliquefaciens in aquaculture. HighlightsHeat‐inactivated Bacillus amyloliquefaciens FPTB16 was studied as paraprobiotic on catla immunity.The paraprobiotic preparation enhanced immune responses.Immune relevant gene expression was up‐regulated by paraprobiotic.Inclusion of 108 cells g−1 diet showed best immunostimulatory potential.

Dietary Bacillus subtilis FPTB13 and chitin, single or combined, modulate systemic and cutaneous mucosal immunity and resistance of catla, Catla catla (Hamilton) against edwardsiellosis.

Effects of dietary administration of Bacillus subtilis FPTB13 and chitin, single or combined, on the systemic immunity, mucosal immunity and resistance of catla (Catla catla) against Edwardsiella tarda infection were investigated. The probiotic attributes of B. subtilis was tested by conducting antagonism study, safety in catla, in vitro immunomodulation and dietary immunomodulation. Results of these studies indicated the probiotic potential of the strain. From the preliminary dietary immunomodulation study, a dose of 10(9) B. subtilis cells g(-1) was selected for inclusion into diets for subsequent experiments. Experimental diets were prepared by adding B. subtilis (10(9) cells g(-1)), chitin (2%) and their combination to the basal diet. Different systemic and mucosal immunological parameters viz. oxygen radical production, myeloperoxidase content, lysozyme activity, total protein content and alkaline phosphatase activity showed significant enhancement (p<0.05) after 2 weeks of feeding with the combined diet. B. subtilis and chitin alone also significantly elevated most of the immune responses. All the diets significantly increased the resistance of catla against E. tarda challenge. The highest post-challenge survival was observed in combined group (i.e. 63.33%). In conclusion, B. subtilis and chitin, alone or combined, had a health ameliorating effect in catla. The results also collectively suggest the usefulness of applying a combined probiotic and immunostimulant supplemented diet to achieve greater benefits.

Biofloc technology application in indoor culture of Labeo rohita (Hamilton, 1822) fingerlings: The effects on inorganic nitrogen control, growth and immunity

The present study was undertaken to investigate the effect of biofloc-based aquaculture system on inorganic nitrogen control, and growth and immunological responses of rohu (Labeo rohita). Fingerlings of rohu were cultured in indoor biofloc tanks in light-limited condition for 16 weeks with daily addition of molasses as carbon source to maintain the C/N ratio at 15. Different water quality parameters were measured at weekly interval. Growth, survival and welfare indices including stress and immunological status were measured after the end of the experimental period. Factor analysis using water quality variables indicated ammonia immobilization by heterotrophic bacteria, rather than nitrification, as the dominant mechanism influencing ammonia removal in the biofloc system. Ammonia immobilization was concomitant with microbial biomass production, as also revealed through factor analysis. The biofloc culture system enhanced the growth of rohu significantly than the control fish. As a measure of stress, the serum glucose content did not differ significantly between the fish cultured in biofloc and control system. Among the immunological parameters, respiratory burst and alkaline phosphatase activity showed significant enhancement in fish grown in biofloc system than the control. However, myeloperoxidase activity and total serum protein content did not show any statistically significant difference between biofloc and control system. The enhanced growth and welfare of the cultured fish may be attributed to in situ maintenance of water quality within the biofloc system and presence of microbial floc.

Susceptibility and pathological consequences of catla, Catla catla (Hamilton) experimentally infected with Edwardsiella tarda

Abstract The present study tested the susceptibility and pathological changes of catla, Catla catla (Hamilton) infected with Edwardsiella tarda (ET-PG-29). The bacterium was isolated from the kidney of a diseased pangas catfish. To determine the median lethal dose (LD50), C. catla were challenged with this bacterium (108-103 CFU ml-1), and the LD50 was calculated as 105.5 CFU ml-1. Another set of healthy C. catla were injected intraperitoneally with the LD50 dose to induce edwardsiellosis. The clinical signs of the infected C. catla were observed and recorded. Tissues such as kidney, liver, intestine, heart, and gill from the infected fish with clinical signs of edwardsiellosis were used for histopathology. The clinical and gross signs were first visible at 1 d post-injection, and the infected fish showed typical signs of hemorrhagic septicemia. The most striking histopathological features were found in the kidney which showed multi-focal necrosis with the formation of granuloma indicating an inflammatory response against the pathogen. The intestine displayed goblet cell hyperplasia, the liver showed hydropic degeneration with hyperemic central veins, and there was inflammation of gill lamellae and cardiac myositis associated with leucocyte infiltration. Collectively, the results confirmed the susceptibility of C. catla to E. tarda infection and that this bacterium is a threat to C. catla in aquaculture practices.

Effects of waterborne iron on fry of Catla catla (Ham.), Labeo rohita (Ham.) and Cirrhinus mrigala (Ham.)

Effects of waterborne iron on Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala) fry was evaluated in the present study. In short-term definitive test a concentration series of 8, 10, 12, 14, 16, 18, 20, 22 and 24 mg l-1 of iron were selected. In long-term partial life cycle test 1.0, 2.0, 3.0, 5.0 and 6.0 mg l-1 of iron were selected to observe the behavioural changes, feeding rate, growth rate and bioaccumulation of iron in different organs of fishes. Supplement of iron was done by adding FeSO4 to get the test concentrations. Rohu showed highest tolerance to iron toxicity. The lowest 96 h LC50 value was found for mrigal as 11.21 ± 0.53 mg l-1 whereas the highest was observed in rohu as 16.75 ± 0.96 mg l-1. Among the organs tested, comparatively gill showed higher iron accumulation and muscle showed the lowest. However, rate of change of iron accumulation in gills w.r.t toxicant concentration was lowest as compared to other tissues. Histopathological study of gill showed the evidence of iron accumulation and erosion of secondary gill lamellae. In long-term partial life cycle test reduction in feeding rate, behavioural changes and reduced weight gain was observed. Mrigal showed highest accumulation and catla showed the lowest.

Modulation of systemic and mucosal immune responses of Catla catla (Hamilton, 1822) experimentally challenged with gill monogeneans

ABSTRACT The present study investigated the modulation of systemic and mucosal immunity of catla (Catla catla) experimentally challenged with gill monogeneans. Fingerlings of catla (24.2±1.5g) without any parasites were randomly distributed into two groups each comprising quadruplicate tanks (10 fish per tank). The fish in the infected group were challenged with gill monogeneans by cohabitation method. The control group fish were not exposed to parasites. Serum and mucus were collected from both control and infected fish and different immunological parameters were measured at weekly interval for four weeks. Monogeneans on the fish gills were also quantified from infected fish at weekly interval. Different systemic immunological parameters viz. myeloperoxidase content, alkaline phosphatase and hemolytic activity of serum showed a significant increase (p<.05) in infected group. However, respiratory burst activity, total serum protein and anti‐protease activity did not show any significant enhancement (p<.05) in infected group compared to control. In case of mucosal parameters, myeloperoxidase content, alkaline phosphatase activity, total protein content and anti‐protease activity of mucus showed significant enhancement (p<.05) in infected group compared to control. Parasite prevalence was 100% in the infected group in all the sampling weeks. The mean intensity of parasites was progressively increased and the highest number of monogeneans per gill (45±4.56) was observed during 4th week post challenge. Control group had mean intensity and prevalence of zero. In conclusion, there was the participation of immune system components against monogenean infection in catla. However, the progressive increase in monogenean intensity indicates some immune evasion mechanism available with the monogenean to co‐exist with the host in the face of hosts immune responses. HIGHLIGHTSCatla was challenged with monogeneans by cohabitation.Systemic and mucosal immunity were modulated.Mean intensity of parasites was progressively increased.Results indicated possible immune evasion mechanism by monogenean.

Immunological, Haematological and Biochemical Responses of Bata (Labeo bata), Naturally and Experimentally Infected with Aphanomyces invadans

The effect of the oomycete, Aphanomyces invadans, on immunological, haematological and biochemical responses of bata (Labeo bata) was investigated in the present study. The oomycete, recovered from naturally infected ulcerated bata, was used for experimental infections in apparently healthy bata. Intramuscular injection using a zoospore dose of 1×105 spores/ml produced lesions at 5 days post-infection (p.i.) and by 8-9 days p.i., all the lesions became necrotic. Cohabitation of epizootic ulcerative syndrome-affected and apparently healthy bata produced lesions 7 days p.i. Immunological parameters, including superoxide anion production, nitric oxide production, leucocyte proliferation and lysozyme activity, showed significantly higher values in the infected groups than the apparently healthy bata. Among the haematological parameters, red blood cell count, haemoglobin and packed cell volume values were significantly lower than the healthy bata, while white blood cell counts were significantly higher. Biochemical parameters including total serum protein, serum glutamate pyruvate transaminase and serum glutamate oxaloacetate transaminase activity, showed significantly higher values in the infected groups, whereas the serum alkaline phosphatase activity was higher but statistically non-significant. The results suggest that there was a strong physiological response against A. invadans infection in bata.