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

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.

Automated summary

The study found that supplementing zebrafish with 4 x 10^6 CFU PA g(-1) improved their growth and reproductive performance, as well as enhancing mucosal immune responses. Additionally, this concentration of PA also impacted alkaline phosphatase activity in skin mucus, intestinal villus length, and the expression of the Cyp19a gene.