Summary of SEM observations of swarm fronts of wild-type P. mirabilis and transposon mutants

GroupStrainOrganisation of flagellar filamentsCellular organization at swarm frontsFigure
Wild type and 1 (control mutants)B4Flagellar filaments localized between adjacent cells and interwoven to form regular helical connectionsCells elongated, similar in length, and organized into rafts of parallel swarmer cells3
2, Poor-swarming mutantsNS77Helical connections formed but composed of fewer flagellar filaments than those observed in wild typeSame as wild type4
G77Evidence of vestigial helical connections but flagellar organization greatly reducedCells lack organization seen in wild-type swarm fronts; cell length reduced4
PS92Helical connections formed but not uniformly throughout swarm frontLarge variation in cell length at swarm front; cells formed poorly organized rafts and were unable to maintain formation4
G78Flagellar filaments organized and interwoven but do not form a regular helical patternCells organized into rafts but were closer together than cells in wild-type swarm fronts4
G64Same as wild typeSame as wild type3
3, Nonswarming mutantsG37No helical connections formed but some short flagellar filaments visibleNo elongation or cellular organization5
G33No helical connections formed, no visible flagellar filamentsCells exhibit slight elongation, have a mucoid appearance, and show some alignment
G93No helical connections formed but some flagellar filaments visibleCells exhibit slight elongation and some alignment at the colony boundary
4, Nonswimming, nonswarming mutantsNS63No helical connections formed, no visible flagellar filamentsLarge variation in cell length with some extensively elongated cells; elongated cells appear to align5