Metagenomic Analysis Revealed Differences in Composition and Function Between Liquid-Associated and Solid-Associated...

Area of Science:

• Rumen microbiology
• Animal nutrition
• Metagenomics

Background:

• The rumen microbiome is vital for ruminant digestion of plant material.
• Understanding the distinct roles of liquid-associated (LA) and solid-associated (SA) rumen microbial communities is crucial for optimizing rumen function and animal health.
• Key microbial taxa and their genetic functions in ruminal degradation remain incompletely understood.

Purpose of the Study:

• To investigate the differences in microbial composition and genetic functions between LA and SA rumen systems.
• To specifically analyze the degradational potential of these systems towards carbohydrates.
• To identify key microbial biomarkers differentiating the LA and SA environments.

Main Methods:

• Rumen contents from nine sheep were fractionated into LA and SA systems using elution and centrifugal precipitation.
• Metagenome sequencing was employed to analyze microbial community structure and functional gene content.
• Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology (KO) and Carbohydrate-Active Enzymes (CAZymes) were used for functional annotation.

Main Results:

• While dominant species composition was similar, SA microorganisms exhibited higher relative abundance across all taxa compared to LA.
• Fiber-degrading bacteria (e.g., Ruminococcus, Treponema, Fibrobacter) were more abundant in the SA system, whereas Prevotella was less abundant.
• SA microorganisms were dominant in cellulose degradation, while LA microorganisms were more significant in starch utilization.
• SA microbes showed greater importance in metabolic functions, including carbohydrate and amino acid metabolism.

Conclusions:

• Key differential biomarkers between LA and SA systems include Prevotella, Ruminococcus, Treponema, and Fibrobacter.
• Ruminal microbes degrade carbohydrates synergistically, with SA systems primarily focusing on cellulose and hemicellulose, and LA systems on starch.
• The findings highlight the specialized roles of SA and LA microbial communities in ruminant carbohydrate metabolism.