This document outlines bacterial motility via flagella. It discusses the structure and function of bacterial flagella, including their location on cells and how they facilitate locomotion. The key components and assembly of flagella are described. Different patterns of flagellar arrangement are shown, and motility mechanisms like run-and-tumble are explained.

1. Bacterial Motility
Hugh B. Fackrell

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Presentation Outline
l Bacterial Flagella
l Location
l Function
l Structure
l Bacterial vs eukaryotic flagella

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Flagellum vs Pilus
Pilus
Flagellum

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Pilus (fimbriae)
l An appendage of the bacterial cell used for
transfer of genetic information
l Plural pili

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Pili Transfer Plasmids

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Bacterial Flagellum
l A thin appendage arising
from one or more
locations on the surface
of the cell wall
l Cellular locomotion
l Moves cell along
gradients e.g. glucose

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Types of Motility
l Flagellated
– Flagellum-
l coordinated movement
l tumbling movement
– Axial filament- spirochetes
l Gliding- no visible organelles

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Location
l Polar
l Subpolar
l Lateral
l Lophotrichous
l Amphitrichous
l Peritrichous
l Periplasmic

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Polar Flagellum

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Lophotrichous
Flagella
Spirillum volutns
two or more flagella at the
end of the microbe
Photographs show growth
of flagella during
replication

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Amphitrichous
Flagella
l Tufts of flagella at BOTH ends of the
microbe

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Peritrichous Flagella

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Flagellar tufts

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Flagellar tufts

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Spirochetes have
Periplasmic Flagella
l Periplasmic flagella are
also called the axial
filament

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Axial filaments

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Bacterial Flagellum

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Rings of Gram Negative
Flagellum
l M: cell
Membrane
l P: Peptidoglycan
l L: Outer Layer
l S: Spacer

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Flagellar Structure (details)

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Prokaryotic Flagellum

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Flagellar Structures

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Assembly of Flagellum

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Demonstration of Chemotaxis
l Capillary tube
contains attractant
chemical
l Attractants:
– Glucose,Maltose,
Alanine
l Repellents:
– Indole, H+, OH-,
fatty acids

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Flagellar Rotation
l Clockwise: Tumbling
l Counterclockwise: coordinated
l Alternate between two rotations

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“Run & Tumble” motility

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Regulation of Flagellar
Movement

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Movement of Flagella
l Whip
l Egg beater