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Bacterial motility: machinery and mechanisms

Nature Reviews Microbiology volume 20, pages 161–173 (2022)Cite this article

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Abstract

Bacteria have developed a large array of motility mechanisms to exploit available resources and environments. These mechanisms can be broadly classified into swimming in aqueous media and movement over solid surfaces. Swimming motility involves either the rotation of rigid helical filaments through the external medium or gyration of the cell body in response to the rotation of internal filaments. On surfaces, bacteria swarm collectively in a thin layer of fluid powered by the rotation of rigid helical filaments, they twitch by assembling and disassembling type IV pili, they glide by driving adhesins along tracks fixed to the cell surface and, finally, non-motile cells slide over surfaces in response to outward forces due to colony growth. Recent technological advances, especially in cryo-electron microscopy, have greatly improved our knowledge of the molecular machinery that powers the various forms of bacterial motility. In this Review, we describe the current understanding of the physical and molecular mechanisms that allow bacteria to move around.

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Fig. 1: Flagellum-driven swimming motility in bacteria.
Fig. 2: Swarming motility on surfaces.
Fig. 3: Surface-associated twitching motility.
Fig. 4: Gliding motility over surfaces.

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References

  1. Dobell, C. Antony van Leeuwenhoek and His “Little Animals” (Russell & Russell, 1958).

  2. Miyata, M. et al. Tree of motility – a proposed history of motility systems in the tree of life. Genes Cell 25, 6–21 (2020). This review provides a detailed overview of the various forms of motility found across the tree of life.

    CAS  Google Scholar 

  3. Dick, G. J. The microbiomes of deep-sea hydrothermal vents: distributed globally, shaped locally. Nat. Rev. Microbiol. 17, 271–283 (2019).

    CAS  PubMed  Google Scholar 

  4. Raina, J. B., Fernandez, V., Lambert, B., Stocker, R. & Seymour, J. R. The role of microbial motility and chemotaxis in symbiosis. Nat. Rev. Microbiol. 17, 284–294 (2019).

    CAS  PubMed  Google Scholar 

  5. Jarrell, K. F. & McBride, M. J. The surprisingly diverse ways that prokaryotes move. Nat. Rev. Microbiol. 6, 466–476 (2008).

    CAS  PubMed  Google Scholar 

  6. Henrichsen, J. Bacterial surface translocation: a survey and a classification. Bacteriol. Rev. 36, 478–503 (1972).

    CAS  PubMed  PubMed Central  Google Scholar 

  7. Purcell, E. M. Life at low Reynolds number. Am. J. Phys. 45, 3–11 (1977). A classic article that gives a highly accessible introduction to the flow physics of motility at low Reynolds number.

    Google Scholar 

  8. Santiveri, M. et al. Structure and function of stator units of the bacterial flagellar motor. Cell 183, 244–257.e16 (2020).

    CAS  PubMed  Google Scholar 

  9. Deme, J. C. et al. Structures of the stator complex that drives rotation of the bacterial flagellum. Nat. Microbiol. 5, 1553–1564 (2020). Together with Santiveri et al. (2020) provide atomic resolution structures for the stator unit of the flagellar motor and a proposal for a novel rotation model for torque generation.

    CAS  PubMed  PubMed Central  Google Scholar 

  10. Tan, J. et al. Structural basis of assembly and torque transmission of the bacterial flagellar motor. Cell 184, 2665–2679.e19 (2021).

    CAS  PubMed  Google Scholar 

  11. Johnson, S. et al. Molecular structure of the intact bacterial flagellar basal body. Nat. Microbiol. 6, 712–721 (2021). Together with Tan et al. (2021), this article provides the cryo-EM structure of the bacterial flagellar motor basal body.

    CAS  PubMed  PubMed Central  Google Scholar 

  12. Chang, Y. W. et al. Architecture of the type IVa pilus machine. Science 351, aad2001 (2016).

    PubMed  PubMed Central  Google Scholar 

  13. Gold, V. A., Salzer, R., Averhoff, B. & Kuhlbrandt, W. Structure of a type IV pilus machinery in the open and closed state. eLife 4, e07380 (2015). Together with Chang et al. (2016), this article describes the use of cryo-electron tomography to determine the architecture of the type IV pilus machine.

    PubMed Central  Google Scholar 

  14. Hennell James, R. et al. Structure and mechanism of the proton-driven motor that powers type 9 secretion and gliding motility. Nat. Microbiol. 6, 221–233 (2021). This study presents cryo-EM structures of the motor complexes that power gliding motility and type IX protein secretion in Bacteroidetes.

    CAS  PubMed  Google Scholar 

  15. Berg, H. C. & Anderson, R. A. Bacteria swim by rotating their flagellar filaments. Nature 245, 380–382 (1973).

    CAS  PubMed  Google Scholar 

  16. Silverman, M. & Simon, M. Flagellar rotation and the mechanism of bacterial motility. Nature 249, 73–74 (1974). Together with Berg & Anderson (1974), the authors provide evidence that bacterial flagella rotate rigidly rather than wave or beat.

    CAS  PubMed  Google Scholar 

  17. Nakamura, S. & Minamino, T. Flagella-driven motility of bacteria. Biomolecules 9, 279 (2019).

    CAS  PubMed Central  Google Scholar 

  18. Yonekura, K., Maki-Yonekura, S. & Namba, K. Complete atomic model of the bacterial flagellar filament by electron cryomicroscopy. Nature 424, 643–650 (2003).

    CAS  PubMed  Google Scholar 

  19. Macnab, R. M. Examination of bacterial flagellation by dark-field microscopy. J. Clin. Microbiol. 4, 258–265 (1976).

    CAS  PubMed  PubMed Central  Google Scholar 

  20. Hotani, H. Micro-video study of moving bacterial flagellar filaments. III. Cyclic transformation induced by mechanical force. J. Mol. Biol. 156, 791–806 (1982).

    CAS  PubMed  Google Scholar 

  21. Turner, L., Ryu, W. S. & Berg, H. C. Real-time imaging of fluorescent flagellar filaments. J. Bacteriol. 182, 2793–2801 (2000). This pioneering work enabled fluorescent labelling and high-speed imaging of flagellar filaments in vivo.

    CAS  PubMed  PubMed Central  Google Scholar 

  22. Turner, L. & Berg, H. C. Labeling bacterial flagella with fluorescent dyes. Methods Mol. Biol. 1729, 71–76 (2018).

    CAS  PubMed  Google Scholar 

  23. Schuhmacher, J. S., Thormann, K. M. & Bange, G. How bacteria maintain location and number of flagella? FEMS Microbiol. Rev. 39, 812–822 (2015).

    CAS  PubMed  Google Scholar 

  24. Guttenplan, S. B., Shaw, S. & Kearns, D. B. The cell biology of peritrichous flagella in Bacillus subtilis. Mol. Microbiol. 87, 211–229 (2013).

    CAS  PubMed  Google Scholar 

  25. Echazarreta, M. A. & Klose, K. E. Vibrio flagellar synthesis. Front. Cell. Infect. Microbiol. 9, 131 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  26. Swan, M. A. Electron microscopic observations of structures associated with the flagella of Spirillum volutans. J. Bacteriol. 161, 1137–1145 (1985).

    CAS  PubMed  PubMed Central  Google Scholar 

  27. Armitage, J. P. & Macnab, R. M. Unidirectional, intermittent rotation of the flagellum of Rhodobacter sphaeroides. J. Bacteriol. 169, 514–518 (1987).

    CAS  PubMed  PubMed Central  Google Scholar 

  28. Haya, S., Tokumaru, Y., Abe, N., Kaneko, J. & Aizawa, S. Characterization of lateral flagella of Selenomonas ruminantium. Appl. Environ. Microbiol. 77, 2799–2802 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  29. Berg, H. C. E. coli in Motion (Springer, 2003).

  30. Darnton, N. C., Turner, L., Rojevsky, S. & Berg, H. C. On torque and tumbling in swimming Escherichia coli. J. Bacteriol. 189, 1756–1764 (2007).

    CAS  PubMed  Google Scholar 

  31. Berg, H. C. & Brown, D. A. Chemotaxis in Escherichia coli analysed by three-dimensional tracking. Nature 239, 500–504 (1972). This study characterizes the run-and-tumble strategy used by E. coli to navigate spatial gradients of chemical attractants.

    CAS  PubMed  Google Scholar 

  32. Larsen, S. H., Reader, R. W., Kort, E. N., Tso, W. W. & Adler, J. Change in direction of flagellar rotation is the basis of the chemotactic response in Escherichia coli. Nature 249, 74–77 (1974).

    CAS  PubMed  Google Scholar 

  33. Xie, L., Altindal, T., Chattopadhyay, S. & Wu, X.-L. Bacterial flagellum as a propeller and as a rudder for efficient chemotaxis. Proc. Natl Acad. Sci. USA 108, 2246–2251 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  34. Son, K., Guasto, J. S. & Stocker, R. Bacteria can exploit a flagellar buckling instability to change direction. Nat. Phys. 9, 494–498 (2013).

    CAS  Google Scholar 

  35. Attmannspacher, U., Scharf, B. & Schmitt, R. Control of speed modulation (chemokinesis) in the unidirectional rotary motor of Sinorhizobium meliloti. Mol. Microbiol. 56, 708–718 (2005).

    CAS  PubMed  Google Scholar 

  36. Wadhams, G. H. & Armitage, J. P. Making sense of it all: bacterial chemotaxis. Nat. Rev. Mol. Cell Biol. 5, 1024–1037 (2004).

    CAS  PubMed  Google Scholar 

  37. Hazelbauer, G. L., Falke, J. J. & Parkinson, J. S. Bacterial chemoreceptors: high-performance signaling in networked arrays. Trends Biochem. Sci. 33, 9–19 (2008).

    CAS  PubMed  Google Scholar 

  38. Bi, S. & Sourjik, V. Stimulus sensing and signal processing in bacterial chemotaxis. Curr. Opin. Microbiol. 45, 22–29 (2018).

    CAS  PubMed  Google Scholar 

  39. Brown, D. A. & Berg, H. C. Temporal stimulation of chemotaxis in Escherichia coli. Proc. Natl Acad. Sci. USA 71, 1388–1392 (1974).

    CAS  PubMed  PubMed Central  Google Scholar 

  40. Berg, H. C. The rotary motor of bacterial flagella. Annu. Rev. Biochem. 72, 19–54 (2003).

    CAS  PubMed  Google Scholar 

  41. Sowa, Y. & Berry, R. M. Bacterial flagellar motor. Q. Rev. Biophys. 41, 103–132 (2008).

    CAS  PubMed  Google Scholar 

  42. Chevance, F. F. & Hughes, K. T. Coordinating assembly of a bacterial macromolecular machine. Nat. Rev. Microbiol. 6, 455–465 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  43. Yamaguchi, T. et al. Structure of the molecular bushing of the bacterial flagellar motor. Nat. Commun. 12, 4469 (2021).

    CAS  PubMed  PubMed Central  Google Scholar 

  44. Hosu, B. G., Nathan, V. S. & Berg, H. C. Internal and external components of the bacterial flagellar motor rotate as a unit. Proc. Natl Acad. Sci. USA 113, 4783–4787 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  45. Halte, M. & Erhardt, M. Protein export via the type III secretion system of the bacterial flagellum. Biomolecules 11, 186 (2021).

    CAS  PubMed  PubMed Central  Google Scholar 

  46. Reid, S. W. et al. The maximum number of torque-generating units in the flagellar motor of Escherichia coli is at least 11. Proc. Natl Acad. Sci. USA 103, 8066–8071 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  47. Hu, H. et al. Structural basis of torque generation in the bi-directional bacterial flagellar motor. Trends Biochem. Sci. https://doi.org/10.1016/j.tibs.2021.06.005 (2021). This article summarizes recent progress in understanding the structure and function of the stator unit, as well as torque generation and rotational switching in the flagellar motor.

    Article  PubMed  Google Scholar 

  48. Manson, M. D., Tedesco, P., Berg, H. C., Harold, F. M. & Van der Drift, C. A protonmotive force drives bacterial flagella. Proc. Natl Acad. Sci. USA 74, 3060–3064 (1977).

    CAS  PubMed  PubMed Central  Google Scholar 

  49. Al-Otaibi, N. S. & Bergeron, J. R. C. A new spin on flagellar rotation. Nat. Microbiol. 5, 1455–1456 (2020).

    CAS  PubMed  Google Scholar 

  50. Chang, Y. et al. Molecular mechanism for rotational switching of the bacterial flagellar motor. Nat. Struct. Mol. Biol. 27, 1041–1047 (2020). This article describes the use of cryo-electron tomography to reveal the architecture of the flagellar motor in counterclockwise and clockwise conformations, revealing the molecular mechanism underlying rotational switching.

    CAS  PubMed  PubMed Central  Google Scholar 

  51. Tusk, S. E., Delalez, N. J. & Berry, R. M. Subunit exchange in protein complexes. J. Mol. Biol. 430, 4557–4579 (2018).

    CAS  PubMed  Google Scholar 

  52. Yuan, J., Branch, R. W., Hosu, B. G. & Berg, H. C. Adaptation at the output of the chemotaxis signalling pathway. Nature 484, 233–236 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  53. Lele, P. P., Branch, R. W., Nathan, V. S. & Berg, H. C. Mechanism for adaptive remodeling of the bacterial flagellar switch. Proc. Natl Acad. Sci. USA 109, 20018–20022 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  54. Leake, M. C. et al. Stoichiometry and turnover in single, functioning membrane protein complexes. Nature 443, 355–358 (2006).

    CAS  PubMed  Google Scholar 

  55. Lele, P. P., Hosu, B. G. & Berg, H. C. Dynamics of mechanosensing in the bacterial flagellar motor. Proc. Natl Acad. Sci. USA 110, 11839–11844 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  56. Tipping, M. J., Delalez, N. J., Lim, R., Berry, R. M. & Armitage, J. P. Load-dependent assembly of the bacterial flagellar motor. mBio 4, e00551-13 (2013).

    PubMed  PubMed Central  Google Scholar 

  57. Wadhwa, N., Phillips, R. & Berg, H. C. Torque-dependent remodeling of the bacterial flagellar motor. Proc. Natl Acad. Sci. USA 116, 11764–11769 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  58. Nord, A. L. et al. Catch bond drives stator mechanosensitivity in the bacterial flagellar motor. Proc. Natl Acad. Sci. USA 114, 12952–12957 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  59. Terahara, N. et al. Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor. Sci. Rep. 7, 46081 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  60. Chawla, R., Ford, K. M. & Lele, P. P. Torque, but not FliL, regulates mechanosensitive flagellar motor-function. Sci. Rep. 7, 5565 (2017).

    PubMed  PubMed Central  Google Scholar 

  61. Nirody, J. A., Nord, A. L. & Berry, R. M. Load-dependent adaptation near zero load in the bacterial flagellar motor. J. R. Soc. Interface 16, 20190300 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  62. Wadhwa, N., Tu, Y. & Berg, H. C. Mechanosensitive remodeling of the bacterial flagellar motor is independent of direction of rotation. Proc. Natl Acad. Sci. USA 118, e2024608118 (2021).

    CAS  PubMed  PubMed Central  Google Scholar 

  63. Krieg, N. R. Biology of the chemoheterotrophic spirilla. Bacteriol. Rev. 40, 55–115 (1976).

    CAS  PubMed  PubMed Central  Google Scholar 

  64. Metzner, P. Die Bewegung und Reizbeantwortung der bipolar begeißelten Spirillen. Jahrb. Wiss. Bot. 59, 325–412 (1920).

    Google Scholar 

  65. Krieg, N. R., Tomelty, J. P. & Wells, J. S. Jr. Inhibition of flagellar coordination in Spirillum volutans. J. Bacteriol. 94, 1431–1436 (1967).

    CAS  PubMed  PubMed Central  Google Scholar 

  66. Chwang, A. T., Wu, T. Y. & Winet, H. Locomotion of spirilla. Biophys. J. 12, 1549–1561 (1972).

    CAS  PubMed  PubMed Central  Google Scholar 

  67. Winet, H. & Keller, S. R. Spirillum swimming: theory and observations of propulsion by the flagellar bundle. J. Exp. Biol. 65, 577–602 (1976).

    CAS  PubMed  Google Scholar 

  68. Ramia, M. Numerical model for the locomotion of spirilla. Biophys. J. 60, 1057–1078 (1991).

    CAS  PubMed  PubMed Central  Google Scholar 

  69. Berg, H. C. Chemotaxis in bacteria. Annu. Rev. Biophys. Bioeng. 4, 119–136 (1975).

    CAS  PubMed  Google Scholar 

  70. Cohen, E. J. et al. Campylobacter jejuni motility integrates specialized cell shape, flagellar filament, and motor, to coordinate action of its opposed flagella. PLoS Pathog. 16, e1008620 (2020).

    CAS  PubMed  PubMed Central  Google Scholar 

  71. Wolgemuth, C. W., Charon, N. W., Goldstein, S. F. & Goldstein, R. E. The flagellar cytoskeleton of the spirochetes. J. Mol. Microbiol. Biotechnol. 11, 221–227 (2006).

    CAS  PubMed  Google Scholar 

  72. Picardeau, M. Virulence of the zoonotic agent of leptospirosis: still terra incognita? Nat. Rev. Microbiol. 15, 297–307 (2017).

    CAS  PubMed  Google Scholar 

  73. Berg, H. C. How spirochetes may swim. J. Theor. Biol. 56, 269–273 (1976).

    CAS  PubMed  Google Scholar 

  74. Nakamura, S. Spirochete flagella and motility. Biomolecules 10, 550 (2020). This review provides an excellent summary of the current understanding of spirochaete motility.

    CAS  PubMed Central  Google Scholar 

  75. Murphy, G. E., Matson, E. G., Leadbetter, J. R., Berg, H. C. & Jensen, G. J. Novel ultrastructures of Treponema primitia and their implications for motility. Mol. Microbiol. 67, 1184–1195 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  76. Berg, H., Bromley, D. & Charon, N. Leptospiral motility. Symp. Soc. Gen. Microbiol. 28, 285–294 (1978).

    Google Scholar 

  77. Goldstein, S. F. & Charon, N. W. Motility of the spirochete Leptospira. Cell Motil. Cytoskeleton 9, 101–110 (1988).

    CAS  PubMed  Google Scholar 

  78. Tahara, H. et al. The mechanism of two-phase motility in the spirochete Leptospira: swimming and crawling. Sci. Adv. 4, eaar7975 (2018).

    PubMed  PubMed Central  Google Scholar 

  79. Charon, N. W. et al. The unique paradigm of spirochete motility and chemotaxis. Annu. Rev. Microbiol. 66, 349–370 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  80. Vig, D. K. & Wolgemuth, C. W. Swimming dynamics of the Lyme disease spirochete. Phys. Rev. Lett. 109, 218104 (2012).

    PubMed  PubMed Central  Google Scholar 

  81. Berg, H. C. & Turner, L. Movement of microorganisms in viscous environments. Nature 278, 349–351 (1979).

    CAS  PubMed  Google Scholar 

  82. Mehes, E. & Vicsek, T. Collective motion of cells: from experiments to models. Integr. Biol. 6, 831–854 (2014).

    Google Scholar 

  83. Vicsek, T. & Zafeiris, A. Collective motion. Phys. Rep. 517, 71–140 (2012).

    Google Scholar 

  84. Harshey, R. M. Bacterial motility on a surface: many ways to a common goal. Annu. Rev. Microbiol. 57, 249–273 (2003).

    CAS  PubMed  Google Scholar 

  85. Kearns, D. B. A field guide to bacterial swarming motility. Nat. Rev. Microbiol. 8, 634–644 (2010). This review provides an exhaustive and pedagogical introduction to bacterial swarming motility.

    CAS  PubMed  PubMed Central  Google Scholar 

  86. Darnton, N. C., Turner, L., Rojevsky, S. & Berg, H. C. Dynamics of bacterial swarming. Biophys. J. 98, 2082–2090 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  87. Partridge, J. D. & Harshey, R. M. Swarming: flexible roaming plans. J. Bacteriol. 195, 909–918 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  88. McCarter, L. & Silverman, M. Surface-induced swarmer cell differentiation of Vibrio parahaemolyticus. Mol. Microbiol. 4, 1057–1062 (1990).

    CAS  PubMed  Google Scholar 

  89. Alberti, L. & Harshey, R. M. Differentiation of Serratia marcescens 274 into swimmer and swarmer cells. J. Bacteriol. 172, 4322–4328 (1990).

    CAS  PubMed  PubMed Central  Google Scholar 

  90. Harshey, R. M. & Matsuyama, T. Dimorphic transition in Escherichia coli and Salmonella typhimurium: surface-induced differentiation into hyperflagellate swarmer cells. Proc. Natl Acad. Sci. USA 91, 8631–8635 (1994).

    CAS  PubMed  PubMed Central  Google Scholar 

  91. Rather, P. N. Swarmer cell differentiation in Proteus mirabilis. Environ. Microbiol. 7, 1065–1073 (2005).

    CAS  PubMed  Google Scholar 

  92. Copeland, M. F. & Weibel, D. B. Bacterial swarming: a model system for studying dynamic self-assembly. Soft Matter 5, 1174–1187 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  93. Jeckel, H. et al. Learning the space-time phase diagram of bacterial swarm expansion. Proc. Natl Acad. Sci. USA 116, 1489–1494 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  94. Srinivasan, S., Kaplan, C. N. & Mahadevan, L. A multiphase theory for spreading microbial swarms and films. eLife 8, e42697 (2019).

    PubMed  PubMed Central  Google Scholar 

  95. Williams, F. D. & Schwarzhoff, R. H. Nature of the swarming phenomenon in Proteus. Annu. Rev. Microbiol. 32, 101–122 (1978).

    CAS  PubMed  Google Scholar 

  96. Kearns, D. B. & Losick, R. Swarming motility in undomesticated Bacillus subtilis. Mol. Microbiol. 49, 581–590 (2003).

    CAS  PubMed  Google Scholar 

  97. McCarter, L. The multiple identities of Vibrio parahaemolyticus. J. Mol. Microbiol. Biotechnol. 1, 51–57 (1999).

    CAS  PubMed  Google Scholar 

  98. Kohler, T., Curty, L. K., Barja, F., van Delden, C. & Pechere, J. C. Swarming of Pseudomonas aeruginosa is dependent on cell-to-cell signaling and requires flagella and pili. J. Bacteriol. 182, 5990–5996 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  99. Ingham, C. J. & Ben Jacob, E. Swarming and complex pattern formation in Paenibacillus vortex studied by imaging and tracking cells. BMC Microbiol. 8, 36 (2008).

    PubMed  PubMed Central  Google Scholar 

  100. Be’er, A. et al. Paenibacillus dendritiformis bacterial colony growth depends on surfactant but not on bacterial motion. J. Bacteriol. 191, 5758–5764 (2009).

    PubMed  PubMed Central  Google Scholar 

  101. Rhodeland, B., Hoeger, K. & Ursell, T. Physical factors contributing to regulation of bacterial surface motility. Preprint at bioRxiv https://doi.org/10.1101/719245 (2020).

    Article  Google Scholar 

  102. Ping, L., Wu, Y., Hosu, B. G., Tang, J. X. & Berg, H. C. Osmotic pressure in a bacterial swarm. Biophys. J. 107, 871–878 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  103. Daniels, R., Vanderleyden, J. & Michiels, J. Quorum sensing and swarming migration in bacteria. FEMS Microbiol. Rev. 28, 261–289 (2004).

    CAS  PubMed  Google Scholar 

  104. Belas, R. Biofilms, flagella, and mechanosensing of surfaces by bacteria. Trends Microbiol. 22, 517–527 (2014).

    CAS  PubMed  Google Scholar 

  105. Chawla, R., Gupta, R., Lele, T. P. & Lele, P. P. A skeptic’s guide to bacterial mechanosensing. J. Mol. Biol. 432, 523–533 (2020).

    CAS  PubMed  Google Scholar 

  106. Laventie, B. J. & Jenal, U. Surface sensing and adaptation in bacteria. Annu. Rev. Microbiol. 74, 735–760 (2020).

    CAS  PubMed  Google Scholar 

  107. Ilkanaiv, B., Kearns, D. B., Ariel, G. & Be’er, A. Effect of cell aspect ratio on swarming bacteria. Phys. Rev. Lett. 118, 158002 (2017).

    PubMed  PubMed Central  Google Scholar 

  108. Be’er, A. et al. A phase diagram for bacterial swarming. Commun. Phys. 3, 66 (2020).

    Google Scholar 

  109. Peruani, F., Deutsch, A. & Bar, M. Nonequilibrium clustering of self-propelled rods. Phys. Rev. E. 74, 030904 (2006).

    Google Scholar 

  110. Wensink, H. H. et al. Meso-scale turbulence in living fluids. Proc. Natl Acad. Sci. USA 109, 14308–14313 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  111. Zhang, H. P., Be’er, A., Florin, E. L. & Swinney, H. L. Collective motion and density fluctuations in bacterial colonies. Proc. Natl Acad. Sci. USA 107, 13626–13630 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  112. Tuson, H. H., Copeland, M. F., Carey, S., Sacotte, R. & Weibel, D. B. Flagellum density regulates Proteus mirabilis swarmer cell motility in viscous environments. J. Bacteriol. 195, 368–377 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  113. Partridge, J. D. & Harshey, R. M. More than motility: Salmonella flagella contribute to overriding friction and facilitating colony hydration during swarming. J. Bacteriol. 195, 919–929 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  114. Turner, L., Zhang, R., Darnton, N. C. & Berg, H. C. Visualization of flagella during bacterial swarming. J. Bacteriol. 192, 3259–3267 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  115. Turner, L., Ping, L., Neubauer, M. & Berg, H. C. Visualizing flagella while tracking bacteria. Biophys. J. 111, 630–639 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  116. Ford, K. M., Antani, J. D., Nagarajan, A., Johnson, M. M. & Lele, P. P. Switching and torque generation in swarming E. coli. Front. Microbiol. 9, 2197 (2018).

    PubMed  PubMed Central  Google Scholar 

  117. Partridge, J. D., Nhu, N. T. Q., Dufour, Y. S. & Harshey, R. M. Tumble suppression is a conserved feature of swarming motility. mBio 11, e01189-20 (2020).

    PubMed  PubMed Central  Google Scholar 

  118. Mariconda, S., Wang, Q. & Harshey, R. M. A mechanical role for the chemotaxis system in swarming motility. Mol. Microbiol. 60, 1590–1602 (2006).

    CAS  PubMed  Google Scholar 

  119. Sidortsov, M., Morgenstern, Y. & Be’er, A. Role of tumbling in bacterial swarming. Phys. Rev. E. 96, 022407 (2017).

    PubMed  Google Scholar 

  120. Maier, B. & Wong, G. C. L. How bacteria use type IV pili machinery on surfaces. Trends Microbiol. 23, 775–788 (2015).

    CAS  PubMed  Google Scholar 

  121. Burrows, L. L. Pseudomonas aeruginosa twitching motility: type IV pili in action. Annu. Rev. Microbiol. 66, 493–520 (2012).

    CAS  PubMed  Google Scholar 

  122. Craig, L., Forest, K. T. & Maier, B. Type IV pili: dynamics, biophysics and functional consequences. Nat. Rev. Microbiol. 17, 429–440 (2019). This is an in-depth review of the structure, function and dynamics of the bacterial type IV pilus machinery.

    CAS  PubMed  Google Scholar 

  123. Mattick, J. S. Type IV pili and twitching motility. Annu. Rev. Microbiol. 56, 289–314 (2002).

    CAS  PubMed  Google Scholar 

  124. Pelicic, V. Type IV pili: e pluribus unum? Mol. Microbiol. 68, 827–837 (2008).

    CAS  PubMed  Google Scholar 

  125. Jarrell, K. F. & Albers, S. V. The archaellum: an old motility structure with a new name. Trends Microbiol. 20, 307–312 (2012).

    CAS  PubMed  Google Scholar 

  126. Berry, J. L. & Pelicic, V. Exceptionally widespread nanomachines composed of type IV pilins: the prokaryotic Swiss Army knives. FEMS Microbiol. Rev. 39, 134–154 (2015).

    CAS  PubMed  Google Scholar 

  127. Craig, L., Pique, M. E. & Tainer, J. A. Type IV pilus structure and bacterial pathogenicity. Nat. Rev. Microbiol. 2, 363–378 (2004).

    CAS  PubMed  Google Scholar 

  128. Piepenbrink, K. H. DNA uptake by type IV filaments. Front. Mol. Biosci. 6, 1 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  129. Hepp, C. & Maier, B. Kinetics of DNA uptake during transformation provide evidence for a translocation ratchet mechanism. Proc. Natl Acad. Sci. USA 113, 12467–12472 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  130. Ellison, C. K. et al. Retraction of DNA-bound type IV competence pili initiates DNA uptake during natural transformation in Vibrio cholerae. Nat. Microbiol. 3, 773–780 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  131. Evans, K. J., Lambert, C. & Sockett, R. E. Predation by Bdellovibrio bacteriovorus HD100 requires type IV pili. J. Bacteriol. 189, 4850–4859 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  132. Persat, A., Inclan, Y. F., Engel, J. N., Stone, H. A. & Gitai, Z. Type IV pili mechanochemically regulate virulence factors in Pseudomonas aeruginosa. Proc. Natl Acad. Sci. USA 112, 7563–7568 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  133. Schuergers, N. et al. Cyanobacteria use micro-optics to sense light direction. eLife 5, e12620 (2016).

    PubMed  PubMed Central  Google Scholar 

  134. Nakane, D. & Nishizaka, T. Asymmetric distribution of type IV pili triggered by directional light in unicellular cyanobacteria. Proc. Natl Acad. Sci. USA 114, 6593–6598 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  135. Oliveira, N. M., Foster, K. R. & Durham, W. M. Single-cell twitching chemotaxis in developing biofilms. Proc. Natl Acad. Sci. USA 113, 6532–6537 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  136. Ellison, C. K. et al. Obstruction of pilus retraction stimulates bacterial surface sensing. Science 358, 535–538 (2017). This study shows that type IV pili act mechanosensors to enable surface sensing in bacteria.

    CAS  PubMed  PubMed Central  Google Scholar 

  137. Snyder, R. A. et al. Surface sensing stimulates cellular differentiation in Caulobacter crescentus. Proc. Natl Acad. Sci. USA 117, 17984–17991 (2020).

    CAS  PubMed  PubMed Central  Google Scholar 

  138. Dufrêne, Y. F. & Persat, A. Mechanomicrobiology: how bacteria sense and respond to forces. Nat. Rev. Microbiol. 18, 227–240 (2020).

    PubMed  Google Scholar 

  139. Korotkov, K. V., Sandkvist, M. & Hol, W. G. The type II secretion system: biogenesis, molecular architecture and mechanism. Nat. Rev. Microbiol. 10, 336–351 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  140. Skerker, J. M. & Berg, H. C. Direct observation of extension and retraction of type IV pili. Proc. Natl Acad. Sci. USA 98, 6901–6904 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  141. Merz, A. J., So, M. & Sheetz, M. P. Pilus retraction powers bacterial twitching motility. Nature 407, 98–102 (2000).

    CAS  PubMed  Google Scholar 

  142. Clausen, M., Koomey, M. & Maier, B. Dynamics of type IV pili is controlled by switching between multiple states. Biophys. J. 96, 1169–1177 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  143. Beaussart, A. et al. Nanoscale adhesion forces of Pseudomonas aeruginosa type IV Pili. ACS Nano 8, 10723–10733 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  144. Maier, B. et al. Single pilus motor forces exceed 100 pN. Proc. Natl Acad. Sci. USA 99, 16012–16017 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  145. Clausen, M., Jakovljevic, V., Sogaard-Andersen, L. & Maier, B. High-force generation is a conserved property of type IV pilus systems. J. Bacteriol. 191, 4633–4638 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  146. Tala, L., Fineberg, A., Kukura, P. & Persat, A. Pseudomonas aeruginosa orchestrates twitching motility by sequential control of type IV pili movements. Nat. Microbiol. 4, 774–780 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  147. Marathe, R. et al. Bacterial twitching motility is coordinated by a two-dimensional tug-of-war with directional memory. Nat. Commun. 5, 3759 (2014).

    CAS  PubMed  Google Scholar 

  148. Jin, F., Conrad, J. C., Gibiansky, M. L. & Wong, G. C. Bacteria use type-IV pili to slingshot on surfaces. Proc. Natl Acad. Sci. USA 108, 12617–12622 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  149. Gibiansky, M. L. et al. Bacteria use type IV pili to walk upright and detach from surfaces. Science 330, 197 (2010).

    CAS  PubMed  Google Scholar 

  150. Conrad, J. C. et al. Flagella and pili-mediated near-surface single-cell motility mechanisms in P. aeruginosa. Biophys. J. 100, 1608–1616 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  151. Kühn, M. J. et al. Mechanotaxis directs Pseudomonas aeruginosa twitching motility. Proc. Natl Acad. Sci. USA 118, e2101759118 (2021).

    PubMed  PubMed Central  Google Scholar 

  152. Treuner-Lange, A. et al. PilY1 and minor pilins form a complex priming the type IVa pilus in Myxococcus xanthus. Nat. Commun. 11, 5054 (2020).

    CAS  PubMed  PubMed Central  Google Scholar 

  153. Craig, L. et al. Type IV pilus structure by cryo-electron microscopy and crystallography: implications for pilus assembly and functions. Mol. Cell. 23, 651–662 (2006).

    CAS  PubMed  Google Scholar 

  154. Koch, M. D., Fei, C., Wingreen, N. S., Shaevitz, J. W. & Gitai, Z. Competitive binding of independent extension and retraction motors explains the quantitative dynamics of type IV pili. Proc. Natl Acad. Sci. USA 118, e2014926118 (2021).

    CAS  PubMed  PubMed Central  Google Scholar 

  155. McCallum, M., Burrows, L. L. & Howell, P. L. The dynamic structures of the type IV pilus. Microbiol. Spectr. https://doi.org/10.1128/microbiolspec.PSIB-0006-2018 (2019).

    Article  PubMed  Google Scholar 

  156. McCallum, M., Tammam, S., Khan, A., Burrows, L. L. & Howell, P. L. The molecular mechanism of the type IVa pilus motors. Nat. Commun. 8, 15091 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  157. Mancl, J. M., Black, W. P., Robinson, H., Yang, Z. & Schubot, F. D. Crystal structure of a type IV pilus assembly ATPase: insights into the molecular mechanism of PilB from Thermus thermophilus. Structure 24, 1886–1897 (2016).

    CAS  PubMed  Google Scholar 

  158. McBride, M. J. Bacterial gliding motility: multiple mechanisms for cell movement over surfaces. Annu. Rev. Microbiol. 55, 49–75 (2001).

    CAS  PubMed  Google Scholar 

  159. McBride, M. J. & Nakane, D. Flavobacterium gliding motility and the type IX secretion system. Curr. Opin. Microbiol. 28, 72–77 (2015).

    CAS  PubMed  Google Scholar 

  160. Nan, B., McBride, M. J., Chen, J., Zusman, D. R. & Oster, G. Bacteria that glide with helical tracks. Curr. Biol. 24, R169–R173 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  161. Lapidus, I. R. & Berg, H. C. Gliding motility of Cytophaga sp. strain U67. J. Bacteriol. 151, 384–U398 (1982).

    CAS  PubMed  PubMed Central  Google Scholar 

  162. Nakane, D., Sato, K., Wada, H., McBride, M. J. & Nakayama, K. Helical flow of surface protein required for bacterial gliding motility. Proc. Natl Acad. Sci. USA 110, 11145–11150 (2013). This study shows that surface adhesins that enable gliding motility in F. johnsoniae move in a helical path.

    CAS  PubMed  PubMed Central  Google Scholar 

  163. Shrivastava, A., Roland, T. & Berg, H. C. The screw-like movement of a gliding bacterium is powered by spiral motion of cell-surface adhesins. Biophys. J. 111, 1008–1013 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  164. Braun, T. F., Khubbar, M. K., Saffarini, D. A. & McBride, M. J. Flavobacterium johnsoniae gliding motility genes identified by mariner mutagenesis. J. Bacteriol. 187, 6943–6952 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  165. Braun, T. F. & McBride, M. J. Flavobacterium johnsoniae GldJ is a lipoprotein that is required for gliding motility. J. Bacteriol. 187, 2628–2637 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  166. Nelson, S. S., Glocka, P. P., Agarwal, S., Grimm, D. P. & McBride, M. J. Flavobacterium johnsoniae SprA is a cell surface protein involved in gliding motility. J. Bacteriol. 189, 7145–7150 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  167. Lauber, F., Deme, J. C., Lea, S. M. & Berks, B. C. Type 9 secretion system structures reveal a new protein transport mechanism. Nature 564, 77–82 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  168. Pate, J. L. & Chang, L.-Y. E. Evidence that gliding motility in prokaryotic cells is driven by rotary assemblies in the cell envelopes. Curr. Microbiol. 2, 59–64 (1979).

    Google Scholar 

  169. Shrivastava, A., Lele, P. P. & Berg, H. C. A rotary motor drives Flavobacterium gliding. Curr. Biol. 25, 338–341 (2015). This study provides evidence that gliding motility of Bacteriodetes is powered by a rotary molecular motor.

    CAS  PubMed  PubMed Central  Google Scholar 

  170. Shrivastava, A. & Berg, H. C. A molecular rack and pinion actuates a cell-surface adhesin and enables bacterial gliding motility. Sci. Adv. 6, eaay6616 (2020). This study combines biophysical experiments with fluorescence imaging to propose a mechanistic model for gliding motility.

    CAS  PubMed  PubMed Central  Google Scholar 

  171. Shrivastava, A., Johnston, J. J., van Baaren, J. M. & McBride, M. J. Flavobacterium johnsoniae GldK, GldL, GldM, and SprA are required for secretion of the cell surface gliding motility adhesins SprB and RemA. J. Bacteriol. 195, 3201–3212 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  172. Gorasia, D. G. et al. Structural insights into the PorK and PorN components of the Porphyromonas gingivalis type IX secretion system. PLoS Pathog. 12, e1005820 (2016).

    PubMed  PubMed Central  Google Scholar 

  173. Leone, P. et al. Type IX secretion system PorM and gliding machinery GldM form arches spanning the periplasmic space. Nat. Commun. 9, 429 (2018).

    PubMed  PubMed Central  Google Scholar 

  174. Islam, S. T. & Mignot, T. The mysterious nature of bacterial surface (gliding) motility: a focal adhesion-based mechanism in Myxococcus xanthus. Semin. Cell Dev. Biol. 46, 143–154 (2015).

    CAS  PubMed  Google Scholar 

  175. Nan, B. & Zusman, D. R. Novel mechanisms power bacterial gliding motility. Mol. Microbiol. 101, 186–193 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  176. Sun, M., Wartel, M., Cascales, E., Shaevitz, J. W. & Mignot, T. Motor-driven intracellular transport powers bacterial gliding motility. Proc. Natl Acad. Sci. USA 108, 7559–7564 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  177. Nan, B. et al. Myxobacteria gliding motility requires cytoskeleton rotation powered by proton motive force. Proc. Natl Acad. Sci. USA 108, 2498–2503 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  178. Faure, L. M. et al. The mechanism of force transmission at bacterial focal adhesion complexes. Nature 539, 530–535 (2016). By tracking the components of the M. xanthus adhesion complex, this study provides a molecular model for myxobacterial gliding motility.

    CAS  PubMed  PubMed Central  Google Scholar 

  179. Fu, G. et al. MotAB-like machinery drives the movement of MreB filaments during bacterial gliding motility. Proc. Natl Acad. Sci. USA 115, 2484–2489 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  180. Islam, S. T. et al. CglB adhesins secreted at bacterial focal adhesions mediate gliding motility. Preprint at bioRxiv https://doi.org/10.1101/2020.07.22.216333 (2020).

    Article  Google Scholar 

  181. Waterbury, J. B., Willey, J. M., Franks, D. G., Valois, F. W. & Watson, S. W. A cyanobacterium capable of swimming motility. Science 230, 74–76 (1985).

    CAS  PubMed  Google Scholar 

  182. Brahamsha, B. An abundant cell-surface polypeptide is required for swimming by the nonflagellated marine cyanobacterium. Synechococcus. Proc. Natl Acad. Sci. USA 93, 6504–6509 (1996).

    CAS  PubMed  Google Scholar 

  183. Ehlers, K. & Oster, G. On the mysterious propulsion of Synechococcus. PLoS ONE 7, e36081 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  184. Shaevitz, J. W., Lee, J. Y. & Fletcher, D. A. Spiroplasma swim by a processive change in body helicity. Cell 122, 941–945 (2005).

    CAS  PubMed  Google Scholar 

  185. Tilney, L. G. & Portnoy, D. A. Actin filaments and the growth, movement, and spread of the intracellular bacterial parasite, Listeria monocytogenes. J. Cell Biol. 109, 1597–1608 (1989).

    CAS  PubMed  Google Scholar 

  186. Stevens, J. M., Galyov, E. E. & Stevens, M. P. Actin-dependent movement of bacterial pathogens. Nat. Rev. Microbiol. 4, 91–101 (2006).

    CAS  PubMed  Google Scholar 

  187. Lamason, R. L. & Welch, M. D. Actin-based motility and cell-to-cell spread of bacterial pathogens. Curr. Opin. Microbiol. 35, 48–57 (2017).

    CAS  PubMed  Google Scholar 

  188. Miyata, M. & Hamaguchi, T. Prospects for the gliding mechanism of Mycoplasma mobile. Curr. Opin. Microbiol. 29, 15–21 (2016).

    CAS  PubMed  Google Scholar 

  189. Miyata, M. & Hamaguchi, T. Integrated information and prospects for gliding mechanism of the pathogenic bacterium Mycoplasma pneumoniae. Front. Microbiol. 7, 960 (2016).

    PubMed  PubMed Central  Google Scholar 

  190. Hölscher, T. & Kovács, Á. T. Sliding on the surface: bacterial spreading without an active motor. Environ. Microbiol. 19, 2537–2545 (2017).

    PubMed  Google Scholar 

  191. Seminara, A. et al. Osmotic spreading of Bacillus subtilis biofilms driven by an extracellular matrix. Proc. Natl Acad. Sci. USA 109, 1116–1121 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  192. Grau, R. R. et al. A duo of potassium-responsive histidine kinases govern the multicellular destiny of Bacillus subtilis. mBio 6, e00581-15 (2015).

    PubMed  PubMed Central  Google Scholar 

  193. Murray, T. S. & Kazmierczak, B. I. Pseudomonas aeruginosa exhibits sliding motility in the absence of type IV pili and flagella. J. Bacteriol. 190, 2700–2708 (2008).

    CAS  PubMed  Google Scholar 

  194. Matsuyama, T., Bhasin, A. & Harshey, R. M. Mutational analysis of flagellum-independent surface spreading of Serratia marcescens 274 on a low-agar medium. J. Bacteriol. 177, 987–991 (1995).

    CAS  PubMed  PubMed Central  Google Scholar 

  195. Shrout, J. D. A fantastic voyage for sliding bacteria. Trends Microbiol. 23, 244–246 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  196. Lauga, E. & Powers, T. R. The hydrodynamics of swimming microorganisms. Rep. Prog. Phys. 72, 096601 (2009).

    Google Scholar 

  197. Schuech, R., Hoehfurtner, T., Smith, D. J. & Humphries, S. Motile curved bacteria are Pareto-optimal. Proc. Natl Acad. Sci. USA 116, 14440–14447 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  198. Berg, H. C. How bacteria swim. Sci. Am. 233, 36–45 (1975).

    CAS  PubMed  Google Scholar 

  199. Milne, J. L. et al. Cryo-electron microscopy–a primer for the non-microscopist. FEBS J. 280, 28–45 (2013).

    CAS  PubMed  Google Scholar 

  200. Egelman, E. H. The current revolution in cryo-EM. Biophys. J. 110, 1008–1012 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

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Acknowledgements

The authors thank K. Fahrner for critical reading of the manuscript. N.W. is supported by the National Institute of General Medical Sciences of the US National Institutes of Health under award number K99GM134124. H.C.B. has been supported by the US National Institute of Allergy and Infectious Diseases, the US National Science Foundation and the Rowland Institute for Science.

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    Navish Wadhwa & Howard C. Berg

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Glossary

Reynolds number

A dimensionless parameter in the equations of motion of fluids that indicates the relative importance of inertial forces, forces that accelerate fluids and viscous forces, which shear fluids.

Twitching

Movement across surfaces that occurs when thin filaments are extended outwards from the cell, stick to the substratum at their distal tips and then are disassembled at their base.

Gliding

Movement across surfaces that occurs when adhesins, driven along tracks fixed to the cell wall, adhere to the substratum.

Flagellar filaments

Long, thin and rigid components of the bacterial flagellum, subject to changes in crystal polymorphic form which, when rotated at their base, generate thrust that pushes the cell forward.

Bundles

Groups of flagellar filaments rotating in parallel that push a peritrichously flagellated cell forward.

Polar

Flagellation with filaments that appear at one or the other pole: monotrichous, single filaments; lophotrichous, a tuft of filaments.

Brownian motion

Random motion of an object suspended in a fluid caused by collisions with the molecules of the fluid.

Chemotaxis

A behavioural response to chemical gradients whereby cells move towards regions that contain more nutrients (or nutrient homologues) and away from noxious regions.

Random walk

Migration by stepping in directions chosen at random. The walk is biased if steps in a particular direction are longer or more frequent.

Tethered cells

Cells fixed to glass by a single flagellar filament and, instead of rotating the flagellar filament, the motor rotates the cell body.

Stator units

Also known as force-generating units, torque-generating units or MotA–MotB complexes, an assembly of five MotA proteins and two MotB proteins supporting two transmembrane ion channels that powers flagellar rotation.

Proton motive force

The electrochemical gradient of protons across a membrane due to a combination of the membrane potential and the concentration gradient of protons. Protons driven down this electrochemical gradient energize various cellular processes, including flagellar rotation, ATP synthesis and ion transport.

Viscosity

Denoted by either μ or η, a parameter indicating the magnitude of the force required to shear a fluid. Water has a relatively small viscosity, molasses has a relatively large viscosity.

Newtonian fluid

A fluid in which the viscosity does not depend on the rate of shear (for example, water and solutions of Ficoll). Solutions containing long unbranched chains, such as mucus, hyaluronic acid, methyl cellulose or polyvinylpyrrolidone, are not Newtonian fluids.

Osmolytes

Small organic compounds that are synthesized by the cell to affect intracellular or extracellular osmolarity.

Surfactants

Compounds that when added to a liquid lower its surface tension. Soap and detergent are common examples.

Surface tension

The tendency of liquid surfaces to minimize the surface area and resist extension. Liquids with lower surface tension spread more easily.

Pinion

A round gear that transmits motion to a larger gear or a rack.

Rack

A linear gear that engages with the pinion and translates rotational motion into linear motion.

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Wadhwa, N., Berg, H.C. Bacterial motility: machinery and mechanisms. Nat Rev Microbiol 20, 161–173 (2022). https://doi.org/10.1038/s41579-021-00626-4

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