Environmental fluoride exposure disrupts the intestinal structure and gut microbial composition in ducks.

Fluorine (F) and its compounds produced from industrial production and coal combustion can cause air, water and soil contamination, which can accumulate in animals, plants and humans via food chain threatening public health. Fluoride exposure affects liver, kidney, gastrointestinal and reproductive system in humans and animals. Literature regarding fluoride influence on intestinal structure and microbiota composition in ducks is scarce. This study was designed to investigate these effects by using simple and electron microscopy and 16S rRNA sequencing techniques. Results indicated an impaired structure with reduced relative distribution of goblet cells in the fluoride exposed group. Moreover, the gut microbiota showed a significant decrease in alpha diversity. Proteobacteria, Firmicutes and Bacteroidetes were the most abundant phyla in both control and fluoride-exposed groups. Specifically, fluoride exposure resulted in a significant decrease in the relative abundance of 9 bacterial phyla and 15 bacterial genera. Among them, 4 phyla (Latescibacteria, Dependentiae, Zixibacteria and Fibrobacteres) and 4 genera (Thauera, Hydrogenophaga, Reyranella and Arenimonas) weren't even detectable in the gut microbiota of the ducks. In summary, higher fluoride exposure can significantly damage the intestinal structure and gut microbial composition in ducks.