Fig. 2: The S-layer does not prevent B. exovorus predation.
From: Lifecycle of a predatory bacterium vampirizing its prey through the cell envelope and S-layer
a Representative phase contrast images of an overnight co-culture between the wild-type C. crescentus CB15N and B. exovorus. C. crescentus ghost cells (blue arrowhead) and newborn B. exovorus predators (white arrowhead) are shown. Scale bar, 2 μm. b Similar antibacterial efficiency of the B. exovorus predator was measured when the wild-type or the ∆rsaA C. crescentus strains are used as a prey. C. crescentus prey cells were co-incubated with B. exovorus in a microplate for 16 h at 30 °C. Optical density at 660 nm (here represented as the percentage of the initial population) was monitored over time, and metrics were extracted using CuRveR41. rmax corresponds to the killing rate, and s is the time point at which rmax reaches its maximum value. Colored lines correspond to the fit, and dots are values obtained from three technical replicates. The assay was performed four times, and a representative result is shown. c Boxplot representation of the frequency of attachment events of B. exovorus onto the wild-type or ∆rsaA C. crescentus strains 15 min after flowing the B. exovorus cells into the microfluidics chamber. Values correspond to the fraction of prey cells in contact with a predator cell. Bold horizontal bars represent the median value; empty circles represent the mean; the lower and upper boundaries of the internal box plot correspond to the 25th and 75th percentiles, respectively; the whiskers represent the 10th and 90th percentiles. Mean values ± standard deviation and the number of analyzed cells (n) are indicated below. Pairwise comparison and the value of the mean difference and the standard deviation from three biological replicates are indicated above the plot (ns nonsignificant, p = 0.4; two-sided two-sample Fisher–Pitman permutation test). Source data are provided as a Source Data file. d Representative cryo-EM images of B. exovorus attached to the wild-type (WT) C. crescentus CB15N cell surface (left). Scale bar, 0.5 μm. Magnifications of the selected regions representing the prey envelope layers (top right), and the tight contact between the predator and the prey outer layers (bottom right). PHB polyhydroxybutyrate granule, SL S-layer, OM outer membrane, IM inner membrane. The experiment was repeated twice with similar results. Scale bar, 0.2 μm.
