Cytoplasmic projections through the cell wall are called flagella. These protein-based structures resemble threads and are composed of a special protein called flagellin. They serve as a means of propulsion. With the exception of spirochaetes, all motile bacteria have one or more flagella. Different bacterial species have different arrangements and numbers of flagella. These arrangements are named using the Greek word ‘trichos’ meaning hair. The various flagellar arrangements are:
- Monotrichous
- Amphitrichous
- Peritrichous
- Lophotrichous
Lophotrichous Flagella
Lophotrichous bacteria have several flagella that are all present at the same place on their surfaces and work together to propel the bacteria in a certain direction. In lophotrichous bacteria, the tuft of flagella is present at both or one end only. If the flagellar tuft is present at both ends, it is termed amphilophotrichous. These may revolve both clockwise and counterclockwise. The creature advances when rotated in a clockwise direction, whereas it retracts when rotated in an anti-clockwise direction.
In many instances, a specific area of the cell membrane known as the polar organelle surrounds the bases of many flagella. Polar organelles contain ATP and so aid in the supply and transmission of energy to the bidirectional molecular rotational motor located at the base of each individual bacterial flagellum.
Examples of Lophotrichous Bacteria
Helicobacter pylori is an example of a lophotrichous bacterium, which has many flagella that are all situated at the same location on the bacterial surface and work together to propel the bacterium in a single direction. Likewise, Spirillum species have either lophotrichous or amphitrichous flagella. Some other examples of lophotrichous bacteria are as follows:
- Pseudomonas putida
- Pseudomonas fluorescens
- Bartonella bacilliformis
- Agrobacterium helicobacter
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