FIG. 1.

Influence of an rsmA mutation on swarming ability in the absence or presence of rhamnolipids. Inocula of 2 μl from overnight cultures of PAO1 (wild type), PAZH13 (ΔrsmA), or PT712 (rhlA′::Ω-Gm) with the control vector pME6032 (A) or plasmid pME3839 carrying the rhlAB genes under the control of the inducible tac promoter (B) were spotted onto 0.5% agar supplemented with 1 mM IPTG and incubated at 37°C overnight. The amounts of rhamnolipids (Rhl) produced by each strain were assayed in a separate experiment as described in Materials and Methods and are indicated below each swarming plate. The value obtained for PAO1/pME6032 (1.21 ± 0.04 μg/ml) was set at 100%.