Effects of deoxynivalenol-contaminated diet on the composition and diversity of the intestinal microbial community and intestinal ultrastructure of juvenile largemouth bass (Micropterus salmoides)

Deoxynivalenol (DON), a trichothecene in food and feed, is a principal contaminant due to its prevalence worldwide. In order to investigate the effect of DON on the composition and diversity of intestinal microbiota and intestinal ultrastructure, an 8-week feeding trial was conducted to monitor changes in largemouth bass (Micropterus salmoides) in a control group and both a low and high DON contaminated feed group (containing 300 ?g/kg and 600 ?g/kg of DON respectively). The trial was conducted in 12 fibreglass tanks (500 L volume, four replications for each diet) with 30 fish (initial weight 9.85 ? 0.07 g) per tank. Our results suggested that the diversity and abundance of the intestinal microbiota were higher in the high DON experimental group than the control group at the phyla level and genera level. At the phyla level, the relative abundance of Firmicutes, Proteobacteria and Bacteroidetes in the high DON experimental group increased significantly compared with the control group, whereas the relative abundance of Fusobacteria decreased. At the genera level, the first two dominant genera in high DON treatments were different with the control and low DON groups. PIC-RUSt was used to predict the functions of intestinal microbiota among all samples, we found the high abundance of bacterial metagenomes in low and high DON groups is most likely used in metabolism and genetic information processing. TEM images suggested that DON diet could cause varying degrees of damage to the microvilli. All these results implied that DON could trigger dysregulation of intestinal microbiota taxonomic composition and cause intestine ultrastructure damage of juvenile largemouth bass (Micropterus salmoides). The results of this study will increase awareness of the toxic effects of DON on the intestine of largemouth bass and invites the discovery of new ways to combat DON toxicity.