FIG 4.

Swimming velocities of E. coli wild-type and phosphodiesterase mutant strains. Velocities of individual cells of the E. coli wild type (white), the ΔpdeH mutant (gray), and motile suppressor mutants of the ΔpdeH mutant (green) were scored. For statistical analysis, the Kruskal-Wallis rank sum test was applied. Swimming velocities of at least 76 single cells are shown as box plots. Boxes show the lower and upper quartiles. Black horizontal lines represent the median velocities. Dashed lines show extreme values, whereas small black squares represent individual outliers. Comparisons of motile suppressor mutants with the parental ΔpdeH strain all showed statistically significant differences (P < 0.05). Motile suppressor mutants showed swimming velocities restored to the levels observed for the wild type. Black bars represent intracellular c-di-GMP concentrations as measured by LC-MS/MS. A mutant lacking PdeH displayed a 10-fold-increased cellular c-di-GMP concentration (3.5 μM) compared to that of the wild type (0.31 μM). Motile suppressor mutants showed reduced intracellular c-di-GMP concentrations compared to their parental strain (ΔpdeH).