Frequency of flagellar filament formation of a <i>fliHI</i> mutant strain is increased in <i>clpX</i> null and <i>fliA^H14D</i> backgrounds.

<p>A deletion in <i>clpX</i> (<b>A</b>) and the more stable <i>fliA^H14D</i> variant (<b>B</b>) increase the frequency of flagellar filament formation in a <i>fliHI</i> mutant strain. Flagellar formation is further enhanced by combination with an <i>atpA</i> mutation. Top: A montage of representative fluorescent microscopy images is shown. Flagellar filaments were stained using anti-FliC immunostaining and detected by FITC-coupled secondary antibodies (green), DNA was stained using Hoechst (blue) and cell membranes using FM-64 (red). Scale bar 2 µm. The percentage of cells with at least one filament is presented in the upper left corner. Bottom: Histogram of counted flagellar filaments per cell body. Number of counted cells and average number of filaments per cell +/− standard deviation based on Gaussian non-linear regression analysis is given in the upper right hand corner.