Starvation affects the intestinal microbiota structure and the expression of inflammatory-related genes of the juvenile blunt snout bream, Megalobrama amblycephala

Abstract

During aquaculture, problems with feed management could result in starvation of the fish; however, the changes in the intestinal microbiota and morphology of fish with respect to chronic starvation remain incompletely understood. The present study aimed to evaluate the results of starvation in terms of the intestinal health of juvenile blunt snout bream (Megalobrama amblycephala). Feeding regimes was designed as follows: fish allowed to feed continuously were set as the control group (S0), S1 comprised fish starved for 1 week, S2 comprised fish starved for 2 weeks, and S4 comprised fish starved for 4 weeks. We observed significant decreases in intestinal lipase and protease activities in the S2 and S4 groups (P < .05). Compared with the control group, the S4 group showed a disordered lamina epithelialis, more debris, and increased leucocyte infiltration. Gene expression levels of pro-inflammatory factors were significantly elevated (P < .05) only in S4 group compared with that in the S0 group, which confirmed that inflammatory responses were induced by starvation. The intestines of the fish in the S4 group had a significantly different microbial community structure and more pathogenic bacteria. Function prediction suggested that to adapt to starvation conditions, the microbiota modulated specific metabolic pathways. The expression levels of inflammation-associated genes correlated significantly with the composition of the blunt snout bream's intestinal microbial communities during starvation. Taken together, long-term starvation impairs the intestinal structure and changes the structure of the intestinal microbiota, subsequently affecting intestinal digestion and the inflammatory response.