Fig. 1

Strain-wide characterization of bEVs. A. bEV size distribution and yield. The 3D graph depicts bEV secretion by the bacterial strain. X-axis: bEV diameter (nm), y-axis: bEV strain, z-axis: total bEV yield. B. Protein content of each bEV. C. Lipid content of each bEV. D. bEV morphology by TEM. Scale bar = 100 nm. E. Protein profile and LTA expression of each bEV. The upper panel shows Coomassie blue-stained protein profiles of bEVs, and the lower panel presents LTA expression levels. M: molecular weight marker, E: bEV, C: cell lysate. F. Correlations of bEV protein and lipid contents with cytotoxicity. X-axis: MTD of bEVs; y-axis: lipid amount (left) and protein amount in bEVs (right). G. bEV uptake in KEL FIB cells. Immunofluorescence images of cells show PKH26-labeled bEVs in red, actin in green, and nuclei in blue. Ctrl: vehicle control. Scale bar = 20 μm. The graph results depict bEV uptake efficiency (top) and the correlation between bEV size and uptake (bottom). The data are presented as the means ± SDs; n = 11, ^ap < 0.05 vs. L. rhamnosus, ^bp < 0.05 vs. S. thermophilus, ^cp < 0.05 vs. L. plantarum; one-way ANOVA followed by Dunnett’s test.