FIG. 2.

The production of rhamnolipids and elastase by P. aeruginosa is increased in response to the overexpression of pqsE. P. aeruginosa strains carrying either a vector plasmid (black bars) or a plasmid containing tacp-pqsE (striped bars) were grown in LB medium for 18 h, and cells were removed from the medium by centrifugation and filtration. (A) The amount of rhamnolipid present in the cleared growth medium from each culture was determined using the orcinol assay as described in Materials and Methods. An asterisk indicates that the amount of rhamnolipid present was below the detectable limit for the assay. The data presented represent the mean ± SD of results from at least three independent experiments. (B) The elastolytic activity present in the growth medium from each culture was assayed using ECR as described in the Materials and Methods section. The data presented represent the mean ± SD of results from at least four individual experiments.