Plant-based β-mannanase supplemented diet modulates the gut microbiota and up-regulates the expression of immunity and digestion-related genes in Cyprinus carpio

Abstract

Microbiota is an integral component of the intestinal tract and plays a significant role in health status of fish. However, diet and feeding habits are the key factors affecting the intestinal microbiota. Here, a 90-day feeding trial was conducted to investigate the effects of a plant-based β-mannanase supplemented diet on the growth, gut microbiome, and mRNA level of key digestion and immunity-related genes of common carp (Cyprinus carpio). Fish were evenly distributed in 3 groups: control, A1 and A2, and fed 35% CP supplemented with β-mannanase at the rate of 0, 500, and 1000 units/kg diet respectively. At the end of the feeding trial, the intestinal microbiota was profiled by sequencing the v4 region of bacterial 16S rRNA and internal transcribed spacer (ITS) regions of fungal 18S rRNA. Results indicated improved growth performance, changes in richness and diversity of intestinal microbiota and up-regulation of intestinal digestion (Amy, Lip, Tryp, FAS, FABP), and immunity-related (SOD, NK-lys, Def, Lys, IL1-β) genes of A1 and A2 groups of fish as compared to control. This study first time demonstrates that β-mannanase in a plant-based diet could improve the intestinal health of C. carpio via modulation of gut microbiota and up-regulation of host digestion and immunity-related genes.

Keywords

• β-mannanase
• intestinal microbiota
• immunity-related genes
• digestion-related genes
• common carp