Metabolomics analysis reveals the protective effect of fructooligosaccharide on abnormal metabolism of liver in Megalobrama amblycephala induced by Aeromonas hydrophila

Fructooligosaccharide (FOS) is a prebiotic and it can be used as a substitute for antibiotics in the breeding industry. However, the ability of FOS as an antibiotic alternative to protect fish against Aeromonas hydrophila (A. hydrophila) infection remains largely unknown. The purpose of this study was to investigate the protective effect of FOS on the liver of fish infected with A. hydrophila by metabolomics. Three groups were set up including control group (G1), A. hydrophila group (G2), and A. hydrophila+FOS group (G3) in the experiment. LC-MS-based metabolomic method was used to study the changes of metabolites in the liver of Megalobrama amblycephala (M. amblycephala), and to identify different metabolites and related metabolic pathways. Metabolomic analysis indicated that fish infected with A. hydrophila caused alterations of metabolic profiles in liver. Specifically the A. hydrophila causes a significant reduction in lipid metabolism, led to oxidative stress, and energy expenditure. The specific metabolic pathways include taurine and hypotaurine metabolism, purine metabolism, and FoxO signaling pathway. The addition of FOS to the diet reversed the liver metabolic abnormalities caused by A. hydrophila. The expression of related metabolites acetyl phosphate, d-glyceric acid, 2'-deoxyinosine 5'-monophosphate, and adenosine 5'-monophosphate were significantly reversed by dietary FOS compared with A. hydrophila infection. These differential metabolites were mainly involved in lipid metabolism, oxidative stress, energy metabolism, inflammation. In conclusion, dietary FOS significantly improved liver metabolic abnormalities caused by A. hydrophila, our study provide new evidence supporting that FOS can be used to remit the abnormal metabolism of liver caused by A. hydrophila.