The human intestinal bacterium Eggerthella lenta influences gut metabolomes in gnotobiotic mice
The intestinal microbiota and its metabolites play a crucial role in influencing host metabolic health, but the impact of specific microbes remains largely unexplored. In this study, we employed the Oligo-Mouse-Microbiota (OMM12) minimal consortium to investigate the function of Coriobacteriia under controlled conditions in gnotobiotic mice. We examined OMM12 mice, with and without the addition of the dominant gut bacterium *Eggerthella lenta* (E. lenta), feeding them diets with varying fat content and primary bile acids. *E. lenta* successfully colonized the mouse caecum at high relative abundance (median: 27.5%). This colonization was associated with a reduced presence of *Akkermansia muciniphila* and *Enterococcus faecalis*, although these differences were not statistically significant across all groups, as results varied with diet and individual differences. Changes in host parameters, including anthropometry, blood glucose, and cholesterol, as well as liver proteomes, were predominantly influenced by diet. In contrast, the metabolomes in the colon content showed significant differences between the colonization groups. The presence of *E. lenta* was linked to increased levels of latifolicinin C acid and decreased levels of creatine, sarcosine, N,N-dimethylarginine, and N-acetyl-DL-methionine. In summary, while *E. lenta* influenced specific metabolites in the colon, it did not have a significant impact on the mice or liver proteomes under the tested conditions, likely due to substantial individual variability.