Insights into the Donkey Hindgut Microbiome Using Metagenome-Assembled Genomes

The gut microbiota plays an important role in the digestion, absorption, and metabolism of nutrients, as well as in the immunity, health, and behavior of donkeys. While reference genomes and gut microbial gene catalogs have been helpful in understanding the composition of the donkey, there is still a significant gap in sequencing and understanding the functional aspects of donkey gut microbial genomes. In this study, we analyzed metagenomic sequencing data from 26 donkeys' gut samples and successfully assembled 844 microbial metagenome-assembled genomes (MAGs). Surprisingly, 678 (80.33%) of these MAGs appear to belong to previously unidentified species. Our analysis further revealed a total of 292,980 predicted carbohydrate-active enzymes (CAZymes) and 257,893 polysaccharide utilization loci (PULs). Interestingly, these enzymes and loci displayed relatively low similarity matches in public databases. We found that the higher abundances of 36 MAGs in the cecum (such as Prevotella, Desulfovibrio, Alistipes, and Treponema_D) and 9 MAGs in the dorsal colon (such as Limimorpha, Saccharofermentans, and Lactobacillus) were associated with a diverse array of carbohydrate-degrading pathways. Network analysis identified Prevotella and Dysosmobacter as connectors, while Saccharofermentans and Akkermansia were shown as provincial hubs. This suggests their crucial roles in complex carbohydrate degradation and hindgut metabolism in donkeys. These findings underscore the complexity of hindgut metabolism in donkeys and expand our understanding of their gut microbiome. Overall, this study provides a comprehensive catalog of donkey gut microbial genes, revealing novel carbohydrate-degrading enzymes and offering new insights for future research on the donkey gut microbiome.