The effect of Pediococcus acidilactici on mucosal immune responses, growth, and reproductive performance in zebrafish (Danio rerio)

摘要

A completely randomized experimental design carried out to investigate the effects of different levels of Pediococcus acidilactici (PA) including 0 (basal diet as a control diet), 1 x 10(6), 2 x 10(6), 4 x 10(6), and 8 x 10(6) colony-forming unit (CFU) per gram of the diet for 60 days on the mucosal immunity responses, growth, and reproductive performance, in zebrafish, Danio rerio (with mean weigh +/- SE: 120 +/- 10 mg). The obtained results revealed that the best growth and reproduction indices were related to the concentration of 4 x 10(6) CFU PA g(-1) diet (P < 0.05). The maximum activities of mucosal immune responses including total protein, alternative complement system, IgM, and lysozyme were observed in the fish fed with 4 x 10(6) CFU PA g(-1) diet (P < 0.05). Furthermore, the maximum alkaline phosphatase activity of skin mucus was recorded in the fish fed with 8 x 10(6) CFU PA g(-1) diet (P < 0.05). Fish fed with 4 x 10(6) CFU PA g(-1) diet had the highest villus length and width of the intestine (P < 0.05). Supplementing the diet with 4 x 10(6) CFU PA g(-1) diet more significantly enhanced Cyp19a gene expression in comparison with this in other groups. Hence, PA with a concentration of 4 x 10(6) CFU g(-1) diet can be considered as a proper level of probiotic for improving the health, growth, and reproductive performance of the D. rerio.