Overexpression of Flagellin by MogR-Negative L. monocytogenes at RT Results in a Chaining Phenotype

<div><p>(A) Western blot analysis of FlaA levels in cellular fractions of wild-type and Δ<i>mogR</i> strains. L. monocytogenes cultures were grown at RT or 37 °C for approximately 24 h. Secreted, surface-localized, and cytoplasmic FlaA protein was detected by Western blot using a FlaA-specific antibody.</p><p>(B) L. monocytogenes strains wild-type, Δ<i>flaA,</i> Δ<i>mogR,</i> and <i>ΔmogR</i> Δ<i>flaA</i> were grown at RT or 37 °C for approximately 24 h, stained for flagella, and analyzed by phase-contrast microscopy. Open arrowheads indicate flagella. The percentage of chaining events within a given population is shown below each panel. A chaining event was defined as a chain of three or more bacteria. A total of 300 bacterial events were counted for each population. The mean and standard deviation of three independent experiments are given.</p>