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

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. reuter i 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.