# The human intestinal bacterium Eggerthella lenta influences gut metabolomes in gnotobiotic mice

## TL;DR

This study shows that the gut bacterium Eggerthella lenta affects colon metabolites in mice but not overall health or liver proteins.

## Contribution

The study identifies specific metabolite changes caused by Eggerthella lenta in a controlled gut microbiota model.

## Key findings

- Eggerthella lenta colonized mice at high levels and altered specific colon metabolites like latifolicinin C acid.
- The presence of Eggerthella lenta was linked to decreased levels of creatine and related compounds in the colon.
- Host health and liver proteomes were mainly influenced by diet, not by Eggerthella lenta colonization.

## Abstract

The intestinal microbiota and its metabolites are known to influence host metabolic health. However, little is known about the role of specific microbes. In this work, we used the minimal consortium Oligo-Mouse-Microbiota (OMM12) to study the function of Coriobacteriia under defined conditions in gnotobiotic mice. OMM12 mice with or without the addition of the dominant gut bacterium Eggerthella lenta (E. lenta) were fed with diets varying in fat content and primary bile acids. E. lenta stably colonised the mouse caecum at high relative abundances (median: 27.5%). This was accompanied by decreased occurrence of Akkermansia muciniphila and Enterococcus faecalis, but results did not reach statistical significance in all groups depending on diet and inter-individual differences. Changes in host parameters (anthropometry, blood glucose, and cholesterol) and liver proteomes were primarily due to diet. In contrast, metabolomes in colon content differed significantly between the colonisation groups. The presence of E. lenta was associated with elevated levels of latifolicinin C acid and decreased creatine, sarcosine, N,N-dimethylarginine, and N-Acetyl-DL-methionine. In conclusion, E. lenta altered specific metabolites in the colon but did not have significant effects on the mice or liver proteomes under the conditions tested due to marked inter-individual differences.