Methane production related to microbiota in dairy cattle feces

Methane (CH₄) emission from livestock feces, led by ruminants, shows a profound impact on global warming. Despite this, we have almost no information on the syntrophy of the intact microbiome metabolisms, from carbohydrates to the one-carbon units, covering multiple stages of ruminant development. In this study, syntrophic effects of polysaccharide degradation and acetate-producing bacteria, and methanogenic archaea were revealed through metagenome-assembled genomes from water saturated dairy cattle feces. Although CH₄ is thought to be produced by archaea, more edges, nodes, and balanced interaction types revealed by network analysis provided a closed bacteria-archaea network. The CH₄ production potential and pathways were further evaluated through dynamic, thermodynamic and ¹³C stable isotope analysis. The powerful CH₄ production potential benefited from the metabolic flux: classical polysaccharides, soluble sugar (glucose, galactose, lactose), acetate, and CH₄ produced via typical acetoclastic methanogenesis. In comparison, a cooperative model dominated by hydrogenotrophic methanogenic archaea presented a weak ability to generate CH₄. Our findings comprehensively link carbon and CH₄ metabolism paradigm to specific microbial lineages which are shaped related to developmental stages of the dairy cattle, directing influencing global warming from livestock and waste treatment.