Response of intestine microbiota, digestion, and immunity in Pacific white shrimp Litopenaeus vannamei to dietary succinate

Succinate (SA) is the precursor of propionate that influence the intestine physiological function of animals. In this study, we investigated the microbiome , digestive, and immune responses in the intestines of Pacific white shrimp Litopenaeus vannamei fed diets containing different levels of SA: 0 g/kg (Control), 2.5 g/kg (SA1), 5.0 g/kg (SA2), and 10.0 g/kg (SA3) for 56 days. The results showed that dietary SA improved the intestine mucosa morphology, increased the short-chain fatty acids contents, and altered the intestine microbiota composition. Specifically, SA increased the abundances of Proteobacteria and decreased the abundance of Bacteroidetes . The beneficial bacteria including Ruegeria , Lutimonas , Mameliella , and Sphingomonas were enriched in response to dietary SA; these genus might be involved in nutrient metabolism and the degradation of toxic compounds and pollutants . Additionally, dietary SA also improved the activity of digestive enzymes (amylase, lipase , trypsin, and pepsin) and immune enzymes (total antioxidant capacity, phenoloxidase, total nitric oxide synthase , and nitric oxide), and the expression of immune-related genes (prophenoloxidase, anti-lipopolysaccharide factor, lysozyme , heat shock protein 70 , thioredoxin , mucin-1, mucin-2, mucin-5 AC, mucin-5B, and mucin-19) in the intestine of the shrimp. These results revealed that dietary SA had a positive effect on the intestine health of L . vannamei by modulating the microbial composition and SCFA contents, and enhancing the digestive and immune response in the shrimp intestine.