Bacteria Swim by Rotating their Flagellar Filaments

  title={Bacteria Swim by Rotating their Flagellar Filaments},
  author={Howard C. Berg and Robert A. Anderson},
IT is widely agreed that bacteria swim by moving their flagella, but how this motion is generated remains obscure1,2. A flagellum has a helical filament, a proximal hook, and components at its base associated with the cell wall and the cytoplasmic membrane. If there are several flagella per cell, the filaments tend to form bundles and to move in unison. When viewed by high-speed cinematography, the bundles show a screw-like motion. It is commonly believed that each filament propagates a helical… 
Bacteria can swim without rotating flagellar filaments
The observed screw-like propulsive motion of bacterial flagella can be understood as either a rigid corkscrew rotating in a sort of journal bearing or the flagellum is firmly attached to the cell wall and moves by the propagation of helical waves.
Bacterial motility: handedness and symmetry.
  • H. Berg
  • Biology
    Ciba Foundation symposium
  • 1991
By measuring concentrations of certain chemicals as they move through their environment, making temporal comparisons and modulating the direction of flagellar rotation, bacteria accumulate in regions that they find more favourable.
Flagellar rotation and the mechanism of bacterial motility
BACTERIAL flagella are generally composed of three morphologically distinguishable regions: the long flagellar filament, the hook, and the basal structure which is composed of an intricate set of disks and rods attaching the hook to the cell membrane and cell wall.
Functional Regulators of Bacterial Flagella.
This review describes regulatory proteins that control motility at the level of torque generation in the flagellum that are essential for motility, niche colonization, and pathogenesis.
Ion transport and rotation of bacterial flagella
A model for the electromechanical coupling between ion flow and flagellar rotation is proposed and it is shown that this coupling is driven by the translocation of ions down an electrochemical gradient.
Evidence that gliding motility in prokaryotic cells is driven by rotary assemblies in the cell envelopes
It is proposed that gliding motility in bacteria is based on rotary assemblies located in the cell envelope and that these assemblies may be analogous to basal regions of bacterial flagella, and the active movement of latex spheres along surfaces of gliding bacteria appears to depend on mechanisms responsible for motility.
The surprisingly diverse ways that prokaryotes move
Regardless of the type of motility machinery that is employed, most motile microorganisms use complex sensory systems to control their movements in response to stimuli, which allows them to migrate to optimal environments.
Flagellar Hook Flexibility Is Essential for Bundle Formation in Swimming Escherichia coli Cells
Genetically modified the hook so that it could be stiffened by binding streptavidin to biotinylated monomers, impeding their motion relative to each other resulted in atypical swimming behavior as a consequence of disrupted bundle formation, in agreement with the universal joint model.


How Bacteriophage χ Attacks Motile Bacteria
Bacteria whose motility has been strongly inhibited by cold or anaerobic conditions still adsorb chi at the filaments and bases of flagella if a high multiplicity is used, which indicates that direct collisions with the bases may also be possible.
Relationship between Cell Wall, Cytoplasmic Membrane, and Bacterial Motility
High-resolution electron microscopy of polarly flagellated bacteria revealed that their flagella originate at a circular, differentiated portion of the cytoplasmic membrane approximately 25 nm in diameter, and an explanation for the membrane displacement is given.
Flagellar Assembly Mutants in Escherichia coli
Genetic and biochemical analysis of mutants defective in the synthesis of flagella in Escherichia coli revealed an unusual class of mutants that were found to produce short, curly, flageella-like filaments with low amplitude, suggested to be "polyhooks", repeated end-to-end polymers of the hook portion of the flagellum.
Fine Structure and Isolation of the Hook-Basal Body Complex of Flagella from Escherichia coli and Bacillus subtilis
Two types of basal body structures are proposed, as exemplified by E. coli and B. subtilis, which directly reflect the structure of the gram-negative and gram-positive cell envelopes.
Locomotion of Spirilla.
A mutant of Salmonella possessing straight flagella.
It was shown by electron microscopy that the component flagella of the straight flagellar bundle were in most instances irregularly twisted about each other, which indicated that the straight mutant originated by a mutation of the structural gene of phase 2 flageLLin.
A note on the helical movement of micro-organisms
  • A. Chwang, T. Y. Wu
  • Biology
    Proceedings of the Royal Society of London. Series B. Biological Sciences
  • 1971
This note seeks to evaluate the self-propulsion of a micro-organism, in a viscous fluid, by sending a helical wave down its flagellated tail by determining the power required for propulsion by means of helical waves, and the hydromechanical efficiency η is defined.