Fig 3. Impact of Rho inactivation on swarming motility of B. subtilis cells.

(A) Motility defect of the NCIB 3610 RM cells can be partially suppressed by the deletion of slrR and ectopic expression of flhO-flhP genes. Bacterial cultures were grown to an OD₆₀₀ 0.5, concentrated and spotted on the plate as described (Materials and methods). The images were acquired after 20 hours of incubation at 37°C. Each icon represents top-grown image of centrally inoculated Petri plate (diameter 9 cm) containing LB and 0.7% of agar. Relevant genotypes are indicated on the side of each image. The repaired back to the wild type NCIB 3610 RM is denoted as rho wt*. The experiment was reproduced at least five times and included three biological replicas for each strain. The results from the representative experiment are presented. (B) Quantitative swarming assay of the indicated NCIB 3610 (blue lines) and isogenic NCIB 3610 RM (red lines) derivative strains. Values represent the mean of at least five experiments. (C) Impact of rho deletion on sense and antisense transcription of the flhO-flhP operon in the B. subtilis 1012 cells. Expression profiles are from the B. subtilis expression data browser (http://genome.jouy.inra.fr/cgi-bin/seb/index.py). Vertical bar on the top line indicates position of predicted putative terminator (shown in D). Sections show annotated genome (top) and expression profiles on the (+) and (–) strands (mid and bottom sections). Wild type (black) and RM (red) profiles are shown. (D) MFOLD [83] predicted secondary structure (ΔG = −16, 30) within flhP asRNA.