(P27-14-26) How Do Probiotics Impact Gut Health? Metabolite Cargoes in Bacterial Extracellular Vesicles (bEVs)

Objectives: Gut microbes and probiotics generate xenometabolites that influence host metabolic, immune, and neuroendocrine function, yet the mechanisms by which these compounds are packaged and transported to host tissues remain unclear. Bacterial extracellular vesicles (bEVs) are membrane-bound particles capable of transporting microbial molecules to host cells. The extent to which strain identity and environmental conditions shape bEV production and cargo composition remains poorly defined. We examined the effects of strain and growth temperature on bEV production, physical characteristics, and metabolite cargo in probiotic cultures.

Methods: Three strains – Lactiplantibacillus plantarum NCIMB8826R (LP), Lacticaseibacillus paracasei BL23 (LC), and Limosilactobacillus reuteri DSM 17938 (LR) – were grown for 24 h at 30°C or 37°C. bEV isolation and characterization by nanoparticle tracking analysis (NTA) and cryo-electron microscopy were combined with three metabolomics platforms to profile bEV metabolites. Metabolite abundances were normalized to vesicle concentration using ANCOVA prior to statistical analyses.

Results: NTA revealed strain- and culture-dependent differences in bEV size and yield. LR produced vesicles with the largest mean size, whereas LC and LP generated higher particle concentrations. Univariate and partial least squares discriminant analysis identified strain-specific bEV metabolite signatures, with anti-inflammatory cyclopropane fatty acid xenolipids and indole-3-lactate enriched in LP at 37°C. Growth temperature also shifted metabolite composition within strains.

Conclusions: bEV metabolite profiles differed by strain and showed temperature-associated signatures, demonstrating that culture conditions shape vesicle production, properties, and cargo. These findings support that probiotic strain selection and culture conditions could be leveraged to engineer “designer probiotics” that deliver targeted xenometabolites, including anti-inflammatory compounds, to host tissues.

Funding Sources: This work was funded by NIH-NIDDK 1R01DK137173-01A1 and a UC Davis School of Medicine Convergence Award.