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Genes and Genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
A flagellum is a tail-like structure that projects from the cell body of certain prokaryotic and eukaryotic cells and is mostly involved in locomotion and movement. There are some notable differences between prokaryotic and eukaryotic flagella, such as protein composition, structure, and mechanism of propulsion. An example of a flagellated bacterium is the ulcer-causing Helicobacter pylori, which uses multiple flagella to propel itself through the mucus lining to reach the stomach epithelium. An example of a eukaryotic flagellated cell is the sperm cell, which uses its flagellum to propel itself through the female reproductive tract. Eukaryotic flagella are structurally identical to eukaryotic cilia, although distinctions are sometimes made according to function and structure.
Molecular Machines
Published in Thomas M. Nordlund, Peter M. Hoffmann, Quantitative Understanding of Biosystems, 2019
Thomas M. Nordlund, Peter M. Hoffmann
Rotational motors that drive whole cells through water with no tracks, like the flagella of bacteria, can also be directional. Again, we refer to the reviews of Howard Berg (and others) on the Escherichia coli and other flagella. At least three distinct types of flagella have been found: bacterial flagella like E. coli’s, eukaryotic flagella (often called cilia or undulipodia), and archaeal flagella.5 In the case of E. coli, five to six flagella extending from random points on the sides of the cell body form a synchronous bundle when they rotate in one direction, driving the cell forward. When the flagella rotate in the opposite direction, they do not bundle but rotate independently, causing the cell to tumble. This tumbling changes the direction the cell is pointed, allowing a change of direction if, for example, an environment lacking in nutrients is encountered. The interested student or instructor is encouraged to explore the classic treatment by Berg on rotational diffusion and directional changes of E. coli.6 Even in this more complex case of rotational motion the central role of asymmetry is clear: drive behavior is not symmetric with respect to direction.
Nano- and Microscale Systems, Devices, and Structures
Published in Sergey Edward Lyshevski, Nano- and Micro-Electromechanical Systems, 2018
Let us study nanobiomotors that can be utilized in devising (synthesis) and design of new high-performance micro- and nanomachines with fundamentally new organization, topologies, and operating principles, enhanced functionality, superior capabilities, and enhanced operating envelopes. In particular, consider the nanobiomotor of E. coli bacteria (see Figure 2.15). The flagella (rotated by nanobiomotors) are used for propulsion. The bacterium is propelled with a maximum speed of 20 μm/sec by flagellar filaments. This filament is driven by a 45-nm rotor of the nanobiomotor embedded in the cell wall. The cytoplasmic membrane forms a stator. This nanobiomotor integrates more than 20 proteins and operates as a result of the axial protonomotive force resulting from the proton flux.
Pathogen contamination of groundwater systems and health risks
Published in Critical Reviews in Environmental Science and Technology, 2023
Yiran Dong, Zhou Jiang, Yidan Hu, Yongguang Jiang, Lei Tong, Ying Yu, Jianmei Cheng, Yu He, Jianbo Shi, Yanxin Wang
Soils and sediments in the vadose zone are effective natural barriers for the downward migration of pathogens, where filtration and adsorption constitute the two main mechanisms to control their transport (Krauss & Griebler, 2011). The effect of filtration is related to the size and shape of sediment grains and pathogens (Figure 2). Generally, smaller pathogens and larger grains allow better transport. The pathogenic organisms with a dimension greater than 5% of the mean diameter of the sediment particles can be significantly retained by filtration (Gerba et al., 2015). Meanwhile, the shape of pathogenic bacteria also matters with the ratio of cell length to width being inversely proportional to the transport rates (Jiang & Bai, 2018). In terms of cell surface appendages, flagella are responsible for bacterial motility and increase transport potential, while fimbriae and pili reduce transport potential by facilitating attachment (Du et al., 2020).
Experimental investigation of biomimetic propulsion through a scaled up branched flagellated artificial nanoswimmer
Published in Australian Journal of Mechanical Engineering, 2022
Shivani Nain, Jitendra Singh Rathore, Niti Nipun Sharma
Both designs of nanoswimmer as depicted in Figure 3; have same length and diameter for flagella, only number of branches and spacing x between branches are getting changed. The motor flagella assembly is mounted on an aluminium cantilever beam which is 30 cm long. The cross section of beam is rectangular with 5 cm by 0.186 cm. Data of deflection of cantilever are recorded for 512 s through Keyence laser micrometre. The schematic of experimental setup for nanoswimmer is shown in Figure 1(b). The time varying deflection is experienced by cantilever beam due to planar motion of branched flagella. A scotch yoke mechanism translates rotational motion into linear motion to engender planar wave movement of attached flagella. The cantilever beam is deflected due to thrust force generated by planar motion of branched flagella in viscous silicon oil medium which is measured by Keyence LS-7601 laser micrometre.
Algicidal bacteria against cyanobacteria: Practical knowledge from laboratory to application
Published in Critical Reviews in Environmental Science and Technology, 2023
Jesús Morón-López, Liliana Serwecińska, Łucja Balcerzak, Sława Glińska, Joanna Mankiewicz-Boczek
Direct attack requires bacteria to actively seek out and attach to cyanobacterial cells, which has often been associated with parasitic or swarming and entrapment lifestyles, as in the case of the genera Bdellovibrio and Myxococcus (Bauer & Forchhammer, 2021). The presence of flagella confers the ability for motility and chemotaxis (Figure 2), but also other multiple roles in virulence, biofilm formation, adhesion and pathogenicity (Duan et al., 2013). Interestingly, cell-to-cell contact was necessary for effective lysis of M. aeruginosa and Aphanizomeon flos-aquae with Alcaligenes denitrificans (Manage et al., 2000), Aeromonas bestiarum (B. S. Park et al., 2022), Bacillus mycoides (Gumbo et al., 2014), and B. cereus (Shunyu et al., 2006), all of them flagellated taxa. Osman et al. (2017) also observed up-regulation of genes encoding flagella formation in Stenotrophomonas rhizophila following close contact and attack against of M. aeruginosa and A. flos-aquae. An exception could be argued from Zeng et al. (2021), who demonstrated that the non-flagellated but filamentous Streptomyces globisporus preyed on M. aeruginosa through direct hyphal contact. However, species of Streptomyces have been shown to be capable of utilizing the motility machinery of other flagellated bacteria at least for spore dispersal (Muok et al., 2021). Therefore, the presence of this organelle not only facilitates the transition between the free-living and particle-attached lifestyle but could also be a prerequisite for some algicidal bacteria to reach, attach to and lyse their prey. The role of flagella in algicidal bacteria has not been explored in previous reviews and research articles, hence it is a topic that deserves further investigation and should be considered when characterizing algicidal bacteria.