Potential Mechanisms of Dietary Potassium Diformate and Sodium Propionate Driving Intestinal Microbiota and Lipid Metabolites to Modulate Intestinal Health of Trachinotus ovatus.

This study aims to investigate the effects of potassium diformate (KDF) and sodium propionate (NaP) on gut digestive and immune functions, intestinal microbiota, and lipid metabolites of Trachinotus ovatus based on multiomics approach. Juvenile T. ovatus (initial weight: 8.65 ± 0.02 g) were subjected to a 56-day feeding regimen. Three isonitrogenous and isolipidic diets, including the control (CG), an additional 6.6 g/kg of KDF, and an additional 6.0 g/kg of NaP were fed to juvenile fish twice daily. Results showed that KDF and NaP supplementation significantly increased the activities of chymotrypsin (Chy), lipase (Lip), α-amylase (α-amy), creatine kinase (CK), Na+K+-ATPase (Na+K+-ATP), γ-glutamyl transferase (γ-GT), alkaline phosphatase (AKP), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and superoxide dismutase (SOD) as well as the expression level of Nrf2 (p < 0.05), while decreased the pH value, malondialdehyde (MDA) content and the mRNA level of Keap1 (p < 0.05). Dietary KDF and NaP markedly enhanced microbial α-diversity and induced significant shifts in microbiota composition through selective modulation of bacterial populations, such as Photobacterium, Mycoplasma, and Mycobacterium (p < 0.05). Besides, KDF and NaP led to notable alterations in the intestinal metabolite lipidome through increasing short-chain fatty acids (SCFAs) levels, upregulating the abundance of phosphatidylcholine (PC), phosphatidylethanolamine, methyl PC (MePC), lysophosphatidic acid, ceramide (Cer), sitosteryl, monogalactosyldiacylglycerol, coenzyme, and lysophosphatidylethanolamine and downregulating the abundance of sphingomyelin and monoglyceride (p < 0.05). The assessment of associations revealed inverse relationships of digestive and antioxidative indices with Photobacterium, but positive correlations with Mycoplasma, Mycobacterium, Ruegeria, Synechococcus, Nautella, Turicibacter, and Roseovarius. This study advances our understanding of KDF and NaP on intestinal health.