2. What is motility?
• Motility is the ability of a cell or organism to
move of its own accord by expending energy.
• Means of motility can range from animals' use
of muscles to single cells which may have
microscopic structures that propel the cell
along
3. Importance of Bacterial Motility
Chemotactic behavior and survival.
Ability to change direction (moving away or towards
repellants or attractants), avoids unfavorable
conditions of habitat and choose favorable
environment
Pathogenesis
• For attachment and colonization of cell wall of
host cell
Microbiology
Nutrition, Water Expulsion
4. Types of movement
There are 2 types of movement
Flagellar movement:
Most motile bacteria
move by use of flagella, threadlike locomotor
appendages extending from the plasma membrane.
and cell wall.
Gliding movement : movement without any appendages.
Brownian movement: movement exhibited by
particles suspended in liquids due to the
bombardment of water molecules.
example: Saccharomyces cerevisiae,
Staphylococcus aureus
5. FLAGELLA
• They are slender, thread like appendages
protruding from the cell wall.
• It measures up to 15 or 20 μm in length and
0.01-0.02 μm in thickness.
7. ULTRASTRUCTURE OF FLAGELLA
• Filament : The longest and most obvious portion
is the filament, which extend from the cell
surface to the tip. It is made up of a protein called
flagellin.
• Basal body: A basal body is embedded in the cell.
The basal body attaches the flagellum to the cell
wall and plasma membrane. It is composed of a
series of rings connected to a central rod.
• Hook : A short, curved segmented, the hook is
present outside the cell wall and connects
filament to the basal body.
8.
9. MECHANISM OF FLAGELLAR
MOVEMENT
• The filament is in the shape of a rigid helix,
and the bacterium moves when this helix
rotates.
• The basal body act as motor and cause
rotation.
• Flagellar rotation determines the nature of
bacterial movement
10.
11. MOVEMENT BY OTHER THAN
FLAGELLAR ROTATION
• Spirochetes shows several types of movement such as
flexing, spinning, free swimming and creeping as they are
flexible and helical bacteria and lake flagella.
• Just within the cell envelop they have flagella like
structure which are know as periplasmic flagella or axial
fibrils.
• The axial fibrils are present in the space between inner
and outer membrane of cell envelope
12. GLIDING MOTILITY
• Some bacteria such as the species of cyanobacteri (eg.
Cytophaga) and mycoplasma show gliding movement when
they come in contact to a solid surface.
• However no organelles are associated with the
movement .
• In the members of cytophagales and cyanobacteria ,
movement helps to find out the substratum eg. Wood,
bark, etc for anchorage and reproduction.
• They secrete slime with the help of which they get
attached to substratum.
14. DETECTION OF MOTILITY
DIRECT DEMONSTRATION OF FLAGELLA:
• Tannic acid staining ( leifson’s method and
Ryu’s method)
• Electron microscopy
INDIRECT DEMONSTRATION OF MOTILITY:
• Craigie tube method
• Hanging drop method
• Semisolid medium
• Dark ground or phase contrast microscope
15. Procedure of Wet Mount Technique
• The organism needs to grow at room temperature in a blood agar
medium for 16 to 24 hours.
• Put a drop of saline onto the microscope slide.
• Now take a sterilized inoculating loop and remove little inoculum from
the culture plate by only touching the margin.
• Then, add the inoculum into the drop of water placed on a glass slide.
• After that, leave a glass slide undisturbed for about 15-20 minutes.
• Afterwards, place the coverslip to the faintly turbid drop of water and
immediately view it under the 40-50X of the objective lens.
• If the motile cells are visible, the process is followed by staining the
bacterial culture. Add a drop of Ryu flagella stain towards the one edge
of the coverslip, which ultimately penetrates the bacterial suspension
through capillary action.
• Then, observe the glass slide after 10 minutes, under the light
microscope upto the power of 100X.
• Finally, note down the results by examining the presence, number and
arrangement of the flagella.
16. Leifson’s Staining Method
• Firstly, take flagellated cell culture slant and put two to three
droplets of distilled water into the culture slant dropwise by using a
sterile pipette without disturbing the cell growth.
• Now incubate the slant for 20 minutes after adding water into it.
• Afterwards, take one drop from the above-prepared suspension
and put it on a clean slide. Then keep a slide in an inclined position.
• The drop needs to flow from one end to another end of the slide to
restrict the flagella folding on the cell.
• Now allow the smear to air dry.
• After the liquid completely evaporates, flood a glass slide with
Leifson’s stain until you observe a shiny thin film.
• Then wash the slide gently with water.
• Afterwards, treat a glass slide with 1 % methylene blue for one
minute.
• Observe the glass slide by putting a drop of oil immersion after
washing the slide with water and air-drying.
17. Result Interpretation
• Wet mount staining method: It stains the
flagella purple.
• Leifson’s staining method: It stains the flagella
red and the bacterial cells blue.
