The insertion region was confirmed by restriction

digest and sequencing. Ultimately, pEC2 was transformed into chemically competent AJW678. Bacterial strains PCI-32765 mw were stored at −80°C in 10% dimethyl sulfoxide (DMSO). Before use, the bacterial strains were streaked onto LB (1% tryptone, 0.5% yeast extract, 0.5% NaCl) agar plates and incubated overnight at 37°C. From the plates, cultures were inoculated into liquid tryptone broth (TB, 1% tryptone, 0.5% NaCl) and grown overnight at 37°C. For bacterial strains containing pPS71, 25 μg/ml of kanamycin were added to the bacterial growth medium. For pEC2, 50 μg/ml of kanamycin were added. For pKK12, 50 μg/ml of chloramphenicol were added. Temporal and spatial expression of flhD, ompR, and rcsB E. coli strains were grown in TB overnight at 37°C. 1 ml of each culture was injected into one channel of a 3 channel flow cell (Stovall, Greensboro NC) with a syringe as described [8]. The flow cell was incubated at room temperature for one

hour without any media flow. After that, TB was pumped selleckchem by an Isma Tec Low Flow High Accuracy Peristaltic Pump (Stovall) into the flow cell at 1 ml/min, equaling 0.33 ml/min per channel. For temporal expression experiments, the flow cell was disconnected after a maximum of 62 h. For spatial expression experiments, the flow cell was disconnected at time points of interest. Each of the investigated bacterial strains was processed at least three times for both temporal and spatial experiments. The flow cell system was kept free of air bubbles by the

bubble trap that is part of the Stovall system. We used a Zeiss Axio Imager M2 upright fluorescence microscope with ApoTome2 (Zeiss Microimaging, Thornwood NY) to detect the fluorescence signals coming from the promoter::gfp fusions. The Zeiss Axio Imager M2 microscope is equipped with a 100×/1.40 oil Paln-Apochromat objective, a Colibri2 higher Sinomenine power LED light source, and a high-resolution monochrome camera for optimal illumination and imaging. For the temporal experiment, fluorescence images were taken at appropriate time points. For the spatial experiments, 20 z-stacking images were taken at one or two time points, separately for fluorescence and bright field. Due to the objective working distance limit, z-sections could be effectively imaged across 8 μm in depth. In cases where biofilms were thicker than 8 μm on some areas of the slides, we selected areas of the biofilm that were consistent with the limitation of the objective. The intensities of the fluorescence signals from aceK::gfp and from flhD::gfp in the ompR and rcsB mutants turned out to be much higher than those from the remaining strains and fusions. For this reason, we performed microscopy for BP1437 at 5% of the available excitation light and for BP1531 and BP1532 at 10%. For BP1470, BP1432, and BP1462, we used 90% of the available excitation light.