Figure 5.

Role of RsmE in AHL and phenazine production. (A) Phenazine production by 30-84 with plasmid pLAFR3 containing either no insert (NI), rsmA, or rsmE. Bacterial strains were grown in LB medium for 24 h at 28°C with shaking. Phenazine was extracted as described previously and total phenazine was quantified at OD₃₆₇. Data points represent means of three replicates ± standard deviations. (B) Repression of phzB expression in 30-84ZN by introduction of extra copies of rsmE but not by introduction of extra copies of rsmA. Treatments included 30-84ZN with plasmid pLAFR3 containing either NI, rsmE, or rsmA. 30-84ZN is a translational phzB::lacZ fusion. The β-galactosidase activities (Miller Units) were determined in triplicate (mean ± SE). (C) Suppression of AHL production by rsmE in trans. AHL accumulation was quantified from overnight cultures of WT with pLAFR3 containing either NI or rsmE using the AHL-specific reporter 30-84I/Z (phzI⁻, phzB::lacZ). The relative amount of AHL was determined by β-galactosidase assays. (D) Effect of inactivation of rsmE on phzB expression. Treatments included the phzB::lacZ reporter (30-84ZN), a phzB::lacZ/GacA⁻ derivative (30-84ZW), and a phzB::lacZ/GacA⁻/RsmE⁻ derivative (30-84ZWE). Bacterial cultures were grown in LB and phzB expression was measured as β-galactosidase activity after 24 h. Data are the means of two replicates from one representative experiment.