Metagenomic insights into the diversity of carbohydrate-degrading enzymes in the yak fecal microbial community.
BACKGROUND
Yaks are able to utilize the gastrointestinal microbiota to digest plant materials. Although the cellulolytic bacteria in the yak rumen have been reported, there is still limited information on the diversity of the major microorganisms and putative carbohydrate-metabolizing enzymes for the degradation of complex lignocellulosic biomass in its gut ecosystem.


RESULTS
Here, this study aimed to decode biomass-degrading genes and genomes in the yak fecal microbiota using deep metagenome sequencing. A comprehensive catalog comprising 4.5 million microbial genes from the yak feces were established based on metagenomic assemblies from 92 Gb sequencing data. We identified a full spectrum of genes encoding carbohydrate-active enzymes, three-quarters of which were assigned to highly diversified enzyme families involved in the breakdown of complex dietary carbohydrates, including 120 families of glycoside hydrolases, 25 families of polysaccharide lyases, and 15 families of carbohydrate esterases. Inference of taxonomic assignments to the carbohydrate-degrading genes revealed the major microbial contributors were Bacteroidaceae, Ruminococcaceae, Rikenellaceae, Clostridiaceae, and Prevotellaceae. Furthermore, 68 prokaryotic genomes were reconstructed and the genes encoding glycoside hydrolases involved in plant-derived polysaccharide degradation were identified in these uncultured genomes, many of which were novel species with lignocellulolytic capability.


CONCLUSIONS
Our findings shed light on a great diversity of carbohydrate-degrading enzymes in the yak gut microbial community and uncultured species, which provides a useful genetic resource for future studies on the discovery of novel enzymes for industrial applications.
['Gong|Ga|G|', 'Zhou|Saisai|S|', 'Luo|Runbo|R|', 'Gesang|Zhuoma|Z|', 'Suolang|Sizhu|S|']
D000818:Animals D001438:Bacteroidaceae D041963:Bacteroidetes D050260:Carbohydrate Metabolism D002417:Cattle D000073561:Clostridiaceae D004950:Esterases D005243:Feces D000069196:Gastrointestinal Microbiome D015870:Gene Expression D014644:Genetic Variation D006026:Glycoside Hydrolases D059014:High-Throughput Nucleotide Sequencing D008031:Lignin D054892:Metagenome D056186:Metagenomics D059013:Microbial Consortia D011133:Polysaccharide-Lyases D018720:Prevotella D012417:Rumen D045857:Ruminococcus
Yak Carbohydrate degradation Lignocellulolytic enzymes Metagenome-assembled genomes Microbiome Plant polysaccharides Taxonomic diversity