The effect of Pediococcus acidilactici MA 18/5M on immune responses and mRNA levels of growth, antioxidant and immune-related genes in zebrafish (Danio rerio)

This study investigated the influence of probiotic Pediococcus acidilactici MA 18/5M on the metabolic enzyme activities and mRNA levels of growth, immunity, and antioxidative-related genes in zebrafish. Zebrafish fed with diets containing P. acidilactici MA 18/5M at 0, 107, 108, and 109 CFU/g levels for eight weeks. The obtained results revealed that the creatine phosphokinase, lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase remained unchanged in all groups (P > 0.05). Dietary P. acidilactici enhanced protease activity relative to the control group (P < 0.05). Compared with the non-treated group, lysozyme activity increased in fish fed with high and medium doses of P. acidilactici, but the mRNA level of lysozyme gene was only up-regulated in the fish received the high dose of P. acidilactici (P < 0.05). Meanwhile, gene expressions of IGF-1, TNF-alpha, GH-1, and catalase were increased by P. acidilactici at 10(7) CFU/g relative to the control group. Conversely, the expression of glutathione S-reductase (GSR) decreased in zebrafish fed with medium and high doses of P. acidilactici compared to the control group. Thus, dietary administration of P. acidilactici MA 18/5 M, especially at 10(7) CFU/g diet, could improve the growth, immunity, and health status of zebrafish.