Effect Of Dietary Supplementation Of Potential Probiotic Weissella Confusa On Innate Immunity, Immune-Related Genes Expression, Intestinal Microbiota And Growth Performance Of Rainbow Trout (Oncorhynchus Mykiss)

Rainbow trout, Oncorhynchus mykiss (average initial weight: 115 +/- 2.6 g), were fed with diets containing different levels of Weissella confusa (0 [control], 1.5 x 10(7) [T-1], 3 x 10(7) [T-2] and 4.5 x 10(7) [T-3] CFU/g) for 2 months. At the end of the experiment, innate immunity, expression of immune-related genes, intestinal microbiota and growth performance of the fish were investigated. A significant increase (p < .05) was seen in the T-2 group compared to other groups in terms of lysozyme activity. In case of alternative complement activity (ACH50), a significant increase (p < .05) was also observed in the T-1 and T-2 treatment groups compared to the other groups. The obtained data from the gene expressions showed a significant up-regulation of tumour necrosis factor-alpha (TNF-alpha) and interleukin 8 (IL-8) in W. confusa-fed fish (p < .05), while interferon gamma (IFN-gamma) gene expression was only significantly up-regulated in T-2. However, the expression of interleukin 10 (IL-10) was down-regulated in the supplemented treatments compared to the control group. Microbiological evaluation revealed that feeding with the W. confusa-supplemented diet significantly enhanced the lactic acid bacteria (LAB) levels (p < .05). Total bacterial count (TBC) was significantly increased in T-2 compared to the control group (p < .05). Also, the growth performance of supplemented treatments remarkably improved compared to the control group (p < .05). These results confirmed the beneficial effects of W. confusa as host-derived potential probiotic in rainbow trout with the appropriate inclusion being 3 x 107 CFU/g.