Effects of starvation and subsequent re -feeding on intestinal microbiota, and metabolic responses in Nile tilapia, Oreochromis niloticus

The effects of starvation and re -feeding on Nile tilapia ( Oreochromis niloticus ) remain incompletely understood so far. In this study, the changes of intestinal microbiota, the metabolic and immune (antioxidant) responses of Nile tilapia ( Oreochromis niloticus ) during starvation and re -feeding stages were investigated. The metabolic responses (cortisol, ALT, AST, and leptin) and immune responses (hsp70, SOD, and CAT) were measured. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the starvation group significantly increased during starvation and decrease after re -feeding. Cortisol levels increase during starvation and decreased after re - feeding. During starvation, the mRNA expression of superoxide dismutase (SOD), catalase (CAT), and heat shock protein (hsp70) were up -regulated while leptin was down -regulated. The microbial taxonomic composition of the starvation group slightly increased from the feeding and re -feeding groups. The relative abundance of the top five bacterial phyla in the intestinal of Nile tilapia (feeding, starvation and re -feeding groups) were Fusobacteria, Proteobacteria, Firmicutes, Bacteriodetes, and Actinobacteria. The relative abundance of the top three intestinal bacterial genera of Nile tilapia (feeding, starvation and re -feeding groups) were Cetobacterium , Romboutsia , Plesiomonas , Bacteroides , and Clostridium senso stricto . Taken together, starvation and re -feeding can modulate the diversity of microbial communities, the metabolic and immune responses of Nile tilapia.