Enhancement of growth, innate immunity, and disease resistance by probiotic Enterococcus faecium MC-5 against Aeromonas hydrophila in Indian major carp Cirrhinus mrigala.

E. faecium MC-5 was isolated and characterized from the gut content of C. carpio and supplemented with a pellet diet at the ratio of 1.0 × 106, 1.0 × 109, and 1.0 × 1012 cfu g-1. Then it was fed to Cirrhinus mrigala for 42 days and the growth performances were evaluated. The growth performance of experimental groups was significantly (P < 0.05) increased than the control group. During 21 and 42 days of the feeding experiment, all the tested immunological parameters such as phagocytic, respiratory burst, lysozyme, acid phosphatase (ACP), superoxide dismutase (SOD), myeloperoxidase activities, and IgM level of experimental groups were significantly (P < 0.05) increased than a control group. After 21 and 42 days of feeding experiment, the fishes were challenged with A. hydrophila, and the relative percentage of survival of experimental groups (PT-I to PT-III) over the control group was recorded from 30.94 to 61.53 and 38.04-77.52 %, respectively. During the challenge experiment, A. hydrophila load was enumerated from dead fish at every 7-day interval. The A. hydrophila load in both the tissues of experimental groups decreased positively from the 7th to 14th day of challenge duration. Overall, the results suggested that the addition of E. faecium MC-5 enhanced the growth performance, immunological response, disease resistance to A. hydrophila, and antioxidant defense system in C. mrigala. Hence these results suggest that E. faecium MC-5 could be used as an advantageous probiotic supplement in aquaculture production.

Dietary effect of Sargassum wightii fucoidan to enhance growth, prophenoloxidase gene expression of Penaeus monodon and immune resistance to Vibrio parahaemolyticus.

The polysaccharide fucoidan from brown seaweed Sargassum wightii was extracted and it was incorporated with pellet diets at three concentrations (0.1, 0.2 & 0.3%). The fucoidan incorporated diets were fed to shrimp Penaeus monodon for 60 days and the growth performance was assessed. The weight gain and SGR of control group was 6.83 g and 9.72%, respectively, but the weight gain and SGR of various concentrations (0.1-0.3%) of fucoidan incorporated diets fed groups of shrimp was increased from 7.30 to 8.20 g and 9.83 to 10.03%, respectively. After 60 days of feeding experiment, the relative quantification of prophenoloxidase gene of experimental groups over control group was analysed by RT-PCR and it was ranged between 2.13 and 7.95 fold increase within 33.52-34.61 threshold cycles, respectively at 0.1-0.3% concentrations of fucoidan. After 60 days of feeding experiment, the P. monodon were challenged with shrimp pathogen Vibrio parahaemolyticus and the mortality percentage was recorded daily up to 21 days. The reduction in mortality percentage of experimental groups over control group was recorded from 44.56 to 72.79%, respectively in 0.1-0.3% of fucoidan incorporated diets fed groups. During challenge experiment, all the immunological parameters such as THC, prophenoloxidase activity, respiratory burst activity, superoxide dismutase activity, phagocytic activity, bactericidal activity and bacterial clearance ability of experimental groups were significantly (P < 0.05) increased than control group. The V. parahaemolyticus load was enumerated from the infected shrimp at every 10 days intervals during challenge experiment. In control group, the Vibrio load was increased in hepatopancreas and muscle tissues from 10th to 21st days of challenge test. But in the experimental groups, the Vibrio load in both the tissues decreased positively from 10th to 21st days of challenge duration. It is concluded that the S. wightii fucoidan had enhanced the innate immunity and increased resistance to V. parahaemolyticus infection in P. monodon.

The effect of fucoidan from brown seaweed Sargassum wightii on WSSV resistance and immune activity in shrimp Penaeus monodon (Fab).

The polysaccharide-fucoidan was extracted from brown seaweed Sargassum wightii and characterized through FT-IR and (13)C &(1)H NMR analysis. The extracted fucoidan was supplemented with pellet diets at three different concentrations (0.1, 0.2 and 0.3%). The fucoidan supplemented diets were fed to Penaeus monodon for 45 days, then challenged with WSSV and the mortality percentage was recorded daily up to 21 days. During the challenge test, the control group showed 100% mortality within 10 days, but in the experimental groups, the mortality percentage (51-72% within 21 days) was decreased considerably (P < 0.05) with respect to the concentrations of fucoidan. The reduction in mortality percentage of experimental groups over control group was ranged from 50.81 to 68.06%. During challenge experiment, the immunological parameters such as THC, prophenoloxidase activity, respiratory burst activity, superoxide dismutase activity and phagocytic activity were measured before injection of WSSV (0 day) and after the injection of WSSV on 10th and 21st days, respectively. All the immunological parameters of experimental groups were significantly (P < 0.05) increased than control group. RT-PCR analysis confirmed the considerable reduction of WSSV DNA copy numbers with respect to the concentration of fucoidan. It was concluded that P. monodon fed with fucoidan of S. wightii supplemented diet had enhanced the innate immunity and increased resistance against WSSV infection.