The effect of Δ nlpA on vesiculation phenotypes. Relative fold OMV production in cultures of the indicated strains grown in LB at 37°C overnight (A, C) or to an OD600 of ~ 0.4 (B, D) was determined as described in Figure 1A. p values refer to comparisons with WT (A, C) or indicated background strain (B, D). Error bars indicate SEM. Statistical comparisons are with WT (A, C) or mutant control strains (B, D) unless denoted by a bracket. *, p ≤ 0.05; n ≥ 4.