BISC209: Motility: Difference between revisions
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1. Flagella are bacterial structures that allow directed movement, called motility. Motility enables bacteria to move towards favorable environments and away from unfavorable ones. Arrangement of flagella varies among species. A flagellum may occur singly at one end, or there may be more than one flagella at one or both ends (polar). Flagella may occur in tufts, or they can be arranged all around the cell (peritrichous). Not all bacteria have flagella. Many are non-motile. | 1. Flagella are bacterial structures that allow directed movement, called motility. Motility enables bacteria to move towards favorable environments and away from unfavorable ones. Arrangement of flagella varies among species. A flagellum may occur singly at one end, or there may be more than one flagella at one or both ends (polar). Flagella may occur in tufts, or they can be arranged all around the cell (peritrichous). Not all bacteria have flagella. Many are non-motile. | ||
2. Flagella can be demonstrated by special staining techniques, they may also be demonstrated indirectly by means of the motility test. Special mordant stains that increase the width of the flagella allow them to be seen with the light microscope. Motility tests rely on the ability of motile bacteria to move through a tube of semisolid medium. The growth of motile bacteria in such a tube will produce turbidity throughout the tube, whereas non-motile organisms will grow only along the line of inoculation. Determination of motility is sometimes important in the characterization and identification of bacteria. <BR><BR> | 2. Flagella can be demonstrated by special staining techniques ([[BISC209: Stains | Special Stains: Endospore, Acid fast, Capsule, and Flagella]])<BR>, they may also be demonstrated indirectly by means of the motility test. Special mordant stains that increase the width of the flagella allow them to be seen with the light microscope. Motility tests rely on the ability of motile bacteria to move through a tube of semisolid medium. The growth of motile bacteria in such a tube will produce turbidity throughout the tube, whereas non-motile organisms will grow only along the line of inoculation. Determination of motility is sometimes important in the characterization and identification of bacteria. <BR><BR> | ||
'''Performing a SIM Motility Test'''<BR> | '''Performing a SIM Motility Test'''<BR> | ||
a) Using your best aseptic technique, remove an inoculum from your unknown culture with an inoculating needle (or loop), and inoculate the sulfide-indole-motility agar “SIM”(2% pancreatic digest of casein, 0.61% peptic animal digest, 0.02% ferrous ammonium sulfate, 0.02% sodium thiosulfate, 0.35% agar) tube by stabbing down the center of the tube, stopping just before the bottom. Withdraw the needle (or loop) through the same inoculation channel. | a) Using your best aseptic technique, remove an inoculum from your unknown culture with an inoculating needle (or loop), and inoculate the sulfide-indole-motility agar “SIM”(2% pancreatic digest of casein, 0.61% peptic animal digest, 0.02% ferrous ammonium sulfate, 0.02% sodium thiosulfate, 0.35% agar) tube by stabbing down the center of the tube, stopping just before the bottom. Withdraw the needle (or loop) through the same inoculation channel. | ||
Revision as of 19:36, 10 January 2010
Techniques to examine Motility
1. Flagella are bacterial structures that allow directed movement, called motility. Motility enables bacteria to move towards favorable environments and away from unfavorable ones. Arrangement of flagella varies among species. A flagellum may occur singly at one end, or there may be more than one flagella at one or both ends (polar). Flagella may occur in tufts, or they can be arranged all around the cell (peritrichous). Not all bacteria have flagella. Many are non-motile.
2. Flagella can be demonstrated by special staining techniques ( Special Stains: Endospore, Acid fast, Capsule, and Flagella)
, they may also be demonstrated indirectly by means of the motility test. Special mordant stains that increase the width of the flagella allow them to be seen with the light microscope. Motility tests rely on the ability of motile bacteria to move through a tube of semisolid medium. The growth of motile bacteria in such a tube will produce turbidity throughout the tube, whereas non-motile organisms will grow only along the line of inoculation. Determination of motility is sometimes important in the characterization and identification of bacteria.
Performing a SIM Motility Test
a) Using your best aseptic technique, remove an inoculum from your unknown culture with an inoculating needle (or loop), and inoculate the sulfide-indole-motility agar “SIM”(2% pancreatic digest of casein, 0.61% peptic animal digest, 0.02% ferrous ammonium sulfate, 0.02% sodium thiosulfate, 0.35% agar) tube by stabbing down the center of the tube, stopping just before the bottom. Withdraw the needle (or loop) through the same inoculation channel.
b) Inoculate a second tube with a known motile control culture, such as E. coli or Proteus sp.,
c) Incubate both tubes at 37˚C for 24-48 hours.
d) Examine the inoculated SIM tubes for growth. If growth is restricted to the line of inoculation and is well demarcated, with no growth in the rest of the agar, the organism is considered non-motile. Growth that occurs throughout the medium indicates a motile organism.
Performing Hanging Drop test for Motility
3. The presence of directed movement rather than Brownian motion can also imply the presence of flagella. A hanging drop slide is a quick way to examine motility. Prepare it by inoculating a loop full of broth culture on a coverslip, turn it upside down and suspend the drop over a depression slide. Examine the bacteria with your microscope at 450x magnification to screen your organism for motility.
