Metagenomic Analysis Reveals Gut Microbiota Structure and Function Alteration between Healthy and Diarrheic Juvenile Yaks

Diarrhea-induced mortality among juvenile yaks is highly prevalent in the pastoral areas of the Qinghai-Tibet Plateau. Although numerous diseases have been linked to the gut microbial community, little is known about how diarrhea affects the gut microbiota in yaks. In this work, we investigated and compared changes in the gut microbiota of juvenile yaks with diarrhea. The results demonstrated a considerable drop in the alpha diversity of the gut microbiota in diarrheic yaks, accompanied by major alterations in taxonomic compositions. At the phylum level, the diarrhea yaks exhibited a higher abundance of Bacteroidota and Proteobacteria than healthy groups, while the level of Firmicutes decreased. At the genus level, the relative abundance of Lactobacillus, Lachnospiraceae_NK4A136_group, Blautia, Enterorhabdus, Roseburia, Colidextribacter, and Bacillus, belonging to beneficial bacteria in diarrhea yaks were significantly decreased, while some pathogenic bacteria such as Bacteroides, Turicibacter, Parasutterella, Eysipelatoclostridium, Parabacteroides, and Escherichia-Shigella significantly increased during diarrhea. Furthermore, PICRust analysis verified the elevation of gut-microbial metabolic pathways in diarrhea groups, including glycine, serine, and threonine metabolism, alanine, aspartate, oxidative phosphorylation, glutamate metabolism, antibiotic biosynthesis, and secondary metabolite biosynthesis. Our study contributes to understanding the diarrhea-yaks gut microbiota variations and suggests that dysbiosis of gut microbiota may be a significant factor for diarrhea in yaks.