FIG 3.

Assessing the effect of cell envelope stressors on B. abortus ΔeipB growth and survival. (A) Envelope stress survival assays. Serially diluted cultures of B. abortus wild-type, ΔeipB, and complementation strains were spotted onto plain TSA plates or TSA plates containing EDTA (2 mM), deoxycholate (0.04%, wt/vol), or ampicillin (5 μg/ml). After 3 to 5 days of growth at 37°C and 5% CO₂, CFU for each condition were enumerated and plotted. This experiment was repeated four times; each data point indicates the mean ± the standard error of the mean. One-way ANOVA, followed by Dunnett’s posttest (to wild-type), supported the conclusion that the eipB deletion strain had significantly fewer CFU than the wild type in the presence of EDTA (****, P < 0.0001), ampicillin (****, P < 0.0001), and deoxycholate (***, P < 0.0003). (B) Light micrograph of B. abortus wild-type (left), ΔeipB (middle), and overexpression (right; induced with 5 mM IPTG) liquid cultures grown overnight in brucella broth. (C) Cryo-EM images of B. abortus wild-type and ΔeipB cells cultivated in liquid broth that either remained untreated or were treated with 2 mM EDTA or 5 μg/ml ampicillin for 4 h.