FIG 3.

Validation of curli production. (a) PQN4 cells with plasmid pBbB8k_csgBACEFG, pBbB8k_csgBACEFG-A6xHis, or no plasmid were grown overnight at a range of arabinose concentrations with 25 μg/ml CR dye. The CR fluorescence of overnight cultures is shown with shaded areas showing averages and standard deviations of 3 replicates for each condition. For each plasmid, 7 samples were taken for Western blotting, each at a particular arabinose concentration, with their specific CR fluorescence reading shown as crosses on the curve. (b) Western blot of an SDS-PAGE gel, using (red ×) anti-CsgA for samples from plasmid pBbB8k_csgBACEFG-bearing cells, or (blue +) anti-6×His for the His-tagged variant. Curli-producing cultures were also imaged with CR dye in a confocal microscope, showing fluorescent aggregates (c and d) with 100 μM arabinose (ara) that were not present without induction (e and f). The CR fluorescence channel is shown in red, overlaid onto the grayscale brightfield channel. Bar, 10 μm.