Swarming phenotype restoration within the Δ rhlA mutants. Swarm plates were incubated for 18 h at 30°C with B. thailandensis E264 wild type strain, both single ΔrhlA mutants as well as the double ΔrhlA mutant. Under these experimental conditions swarming motility is normally favored, as observed with the wild type strain. Experiments were done in triplicate. A) Swarming phenotype restoration of the ΔrhlA mutants with addition of 1, 5, 10 and 25 mg/L of exogenous purified rhamnolipids. B) Cross-feeding experimentation with both ΔrhlA single mutants. Left: mutants placed side-by-side; Right: mutants mixed before plating.