Fig. 1: Membrane vesicles inhibit the growth of pro-inflammatory Enterobacteriaceae by consuming oxygen.

a Respiration of membrane vesicles. The medium contained 20 mM potassium phosphate, 650 mM succinate at a pH of 7 with 325 µg/mL of either wt or ∆hemB MVs. b Electrophoresis on a 0.8% agarose gel for 1 h, hemB was amplified with P3 and P4 primers. Expected amplicon sizes for ∆hemB (hemB::kanR) were 1466 bp and wt hemB was 1114 bp. c Pathway of heme b biosynthesis from 5-aminolevulinate. d Transmission electron microscopy images of ∆hemB and wt MVs. e Cell density of Escherichia coli AR350, Klebsiella pneumoniae ATCC 43816, and Citrobacter rodentium ATCC 51459 after 7 hours of growth in LB aerobically and shaking at 37 °C n = 5 for all cultures. Cultures were inoculated with 1/400 dilution of overnight cultures, 13 mM succinate and 1.6 mg/mL of MVs. Statistical significance was determined using one-way ANOVA with Šídák’s multiple comparisons test, bars represent mean ± SEM. Adjusted p values were as follows, **p < 0.01, ****p < 0.0001.