THE EFFECTS OF PROBIOTICS MIXTURE Bacillus amyloliquefaciens 54A AND B. pumilus 47B ON THE GROWTH PERFORMANCES, INNATE IMMUNITY AND STRESS RESPONSE OF STRIPED CATFISH (Pangansianodon hypophthalmus) IN LABORATORY CONDITION

Ho Thi Truong Thy*, Nguyen Huu Thinh, Nguyen Nhu Tri, Ong Moc Quy,
 Korntip Kannika, Prapansak Srisapoome, Nontawith Areechon, Sasimanas Unajak 
 Faculty of Fisheries
 Nong Lam University
 Linh Trung Ward, Thu Duc District, Ho Chi Minh city, Vietnam
 hothyts@gmail.com

The spore mixture of probiotics candidates (Bacillus amyloliquefaciens 54A and B. pumilus 47B) were used in this study in order to estimate their effect on growth performances, innate immunity, disease resistance to Edwardsiella ictaluri and stress tolerance of striped catfish (Pangansianodon hypothalamus). Three doses of spore probiotics were applied in this study including 1 × 108, 3× 108, and 5×108 CFU/g feed. The average weight gain (AWG), specific growth rate (% SGR), and feed conversion ratio (FCR) were determined after 90 days of feeding trial. Other parameters were also recorded including innate immunity, mortality rate of striped catfish challenged with pathogenic E. ictaluri, and ammonia stress challenge. Confirmation of survival of B. amyloliquefaciens and B. pumilus in fish intestine was done by serial dilution counting and PCR identification by specific primer pairs of Ba-F/Ba-R, and 20-F/BpuR. Although there were no significant effects on % SGR and FCR (P>0.05) of fish, AWG was significantly higher in fish fed with 5× 108 CFU/g feed compared to the control (P<0.05). Similarly, the significant increase of lysozyme, phagocytic activity, and respiratory burst of innate immunity were recorded in fish fed with the highest dose of probiotics (P<0.05). This might induce the more resistance of fish against E. ictaluri infection during 15 days of challenge (Fig 1A). All doses of probiotics stimulated significantly higher stress tolerance to ammonia concentration at 150 ppm TAN (Fig 1B). The high survival of Bacillus used in the experiment was observed in intestine at the end of the trial. This finding opens the new probiotics generation that can be applied in the culture system of striped catfish with aim to improve fish health and their growth performances and consequently, sustainability of this fish culture will be developed.