FIG 4.

ndvB is upregulated in stationary-phase planktonic cultures. (A) Growth curves of planktonic cultures of PA14 carrying the stable (pSC01) and ASV-tagged (pAH08) ndvB-gfp reporters grown in M63-arginine (left) or LB (right) medium. At each time point, samples were removed for optical density measurements and microscopy. Arrows indicate the earliest observation of fluorescence for the unstable reporter (pAH08), which coincides with the entry to stationary phase. (B) Expression of ndvB was measured by qPCR in PA14 planktonic cultures corresponding to the time points of the growth curves in panel A. Expression was quantified at four time points for the M63 cultures (6 h, 9 h, 10.5 h, and 12 h) and five time points for the LB cultures (3 h, 4 h, 5 h, 6 h, and 8 h). ndvB expression is given relative to the 6-h time point for M63 or the 4-h time point for LB. The mean and SEM are presented for the data from three replicate cultures assayed in triplicate qPCRs.