MOTILITY

motility of micro organisms

1. MOTILITY DR.VAISHALI POSTGRADUATE DEPARTMENT OF MICROBIOLOGY

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.

6. Arrangement of flagella Monotrichous- V.cholera,pseudomonas Lophotrichous- spirillum Peritrichous - S.Typhi , E.coli Amphitrichous - Alcaligenes faecalis

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. 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

9. 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

10. 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.

11. MOTILITY BY DIFFERENT BACTERIA

12. 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

13. 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.

14. 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.

15. 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.

16. FLAGELLA UNDER EM

17. CRAIGIE’S TUBE METHOD

18. HANGING DROP METHOD

19. DARK FIELD MICROSCOPY

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