# Characterization of dietary choline uptake by the gut microbiome reveals choline assimilating microbes and influences on host choline metabolism

## TL;DR

This study shows how gut bacteria like L. reuteri process dietary choline, affecting host metabolism and lipid production.

## Contribution

The study identifies new microbial pathways for choline assimilation and their impact on host lipid metabolism.

## Key findings

- L. reuteri assimilates choline and converts it to long chain fatty acylcholines.
- L. reuteri colonization increases serum choline and lysophosphatidylcholine production.
- Choline assimilation by L. reuteri upregulates hepatic genes involved in lipid metabolism.

## Abstract

Choline is an essential nutrient with diverse roles in host metabolism; however, the current understanding of its microbial fate is largely restricted to trimethylamine production. Here, we apply the BioOrthogonal-labeling, Sorting, Sequencing, and mass Spectrometry (BOSSS) workflow to map dietary choline-specific gut microbial interactions. Using an alkyne-modified choline analog (propargylcholine) in mice, we fluorescently label and flow-sort choline-assimilating gut bacteria, identifying a varied set of taxa enriched in probiotic species, including Limosilactobacillus reuteri (L. reuteri). In vitro studies confirm that L. reuteri assimilates choline and converts it to long chain fatty acylcholines. Metabolomic and transcriptomic profiling revealed that L. reuteri colonization, with a choline sufficient diet, selectively elevates serum choline and increases lysophosphatidylcholine production, findings corroborated by transcriptomic evidence of upregulated hepatic genes involved in lipid metabolism. These findings uncover a new metabolic fate for dietary choline, expand the known repertoire of microbiome-derived lipids, and illustrate how specific host–microbe–diet interactions can influence host status.