Host-microbe mutualism drives urea carbon salvage and acetogenesis during hibernation

• DOI: 10.1101/2025.02.13.638127
• Publication Date: 2025-02-18T05:55:20Z
• Authors: Matthew D. Regan; Edna Chiang; Michael Grahn; Marco Tonelli; Fariba M. Assadi-...; Garret Suen; Hannah V. Carey
• Keywords: Hibernation; Acetogenesis; Mutualism

Hibernation is a wintertime survival strategy employed by certain mammals that, through torpor use, reduces overall energy expenditure and permits prolonged fasting. Although fasting resolves the challenge of winter food scarcity, it also removes dietary carbon, critical biomolecular building block. Here, we demonstrate process urea carbon salvage (UCS) in 13 lined ground squirrel, whereby reclaimed gut microbial ureolysis used reductive acetogenesis, producing acetate, short-chain fatty acid (SCFA) major value to host its community. We find that incorporation into acetate more efficient during hibernation than summer active season, while both microbes oxidize for throughout year, ability absorb highest hibernation. Metagenomic data microbiome indicate retention genes involved degradation mucin, an abundant endogenous nutrient. The hydrogen disposal associated with acetogenesis from provides luminal environment sustains fermentation mucin oligosaccharides, thereby generating SCFAs other metabolites usable microbes. Our findings introduce UCS as novel mechanism enables hibernating squirrels their exploit two key nutrient sources (urea mucins) resource limited season.