Human gut bacteria tailor extracellular vesicle cargo for the breakdown of diet- and host-derived glycans

Significance Bacteroides is a prominent genus of the human gut microbiota, which produces large amounts of OMVs (outer membrane vesicles) carrying specific protein cargo. Here, we show that sorting of proteins into OMVs depends on a negatively charged “lipoprotein export signal” (LES). We employed OM (outer membrane) and OMV markers fused to fluorescent proteins to show OMV biogenesis via time-lapse fluorescence microscopy. Additionally, we performed comparative proteomic analyses showing that Bt (Bacteroides thetaiotaomicron) actively alters the OMV content to optimize the utilization of polysaccharides. We conclude that OMV production is highly regulated in Bt. Despite the recognized roles of OMVs in Bacteroides, little is known about their biogenesis. Future studies will focus on further elucidating this undercharacterized process.