Peer pressure from a Proteus mirabilis self-recognition system controls participation in cooperative swarm motility
Fig 2
Cells experiencing Ids mismatch display transient tolerance to lethal concentrations of antibiotics.
A. Killing curves for cells of wildtype (cyan square), Δids (gray "x"), and ΔidsE (magenta circle) harvested from swarm plates and exposed to 100 μg ml-1 ampicillin. Note that the Y-axis is a logarithmic scale. Asterisks represent statistically significant difference between ΔidsE and wildtype (p = 0.02) calculated using a Mann-Whitney test. B. Survival of strains wildtype (cyan square), Δids (gray “x”), and ΔidsE (magenta circle) after swarm colonies were harvested and exposed to 60 μg ml-1 kanamycin (left), 50 μg ml-1 streptomycin (middle), and 1 μg ml-1 ciprofloxacin (right) for 12 hours. Asterisks represent statistically significant difference between ΔidsE and wildtype (p = 0.04) calculated using a Mann-Whitney test. C. Territorial exclusion does not result in long-term growth defects. Optical density at 600 nm (OD600 nm) was measured over time for liquid cultures of wildtype and the co-swarmed Δids strain. Liquid cultures were inoculated using cells isolated by FACS from co-swarm colonies where the Δids strain had been actively excluded from the swarm front.