-Staining procedures typically use harsh
conditions which may significantly change the look of an organism
-- Directional motility: The organism
is moving on its own using specialized structures such as flagella.
--Brownian motion: A special kind of
motion.
In addition to wet mounts, special kinds
of media, motility agar, may be used to indicate motility,
-Organisms typically used.
Comments/Tips:
Note: It is typically harder to see living
organisms, as they are almost clear. This is why staining is done.
-A wet mount allows one to:
-- View organisms in a more natural
state
-- See movement: Taxis:
Bacteria moving with the aid of flagella often use a run and tumble
type of action. Another kind of motility sometimes seen in certain bacteria
is referred to as gliding motility, where the bacteria seem to glide along
a surface without any obvious means of movement.
--Some specific types of directed motility are:
---Chemotaxis: to or away from some chemical
---Phototaxis: to or away from light
---- The organism appears to be moving, wiggling in place, but is actually
not moving on its own.
It is small enough that water molecules push it around.
See demo. Look for spreading away from the line of inoculation. On
plates, the colonies often have a 'fuzzy" edge.
Bacillus cereus: +
Staphylococcus epidermidis: Brownian
Rhodospirillum: +
Saccharomyces: -
-Do not use the 100x oil immersion lens
-To start with, just lay the cover slip over a drop of the culture.
Then try placing the Vaseline on the edges of a cover slip to provide a
spacer, forming a pool of water. Put layer of Vaseline on the heel of the
hand and scrape off the Vaseline with a coverslip.
-Start with yeast
-Pay close attention to the light level. It is very easy to wash out
the specimen with too much light.
Use the diaphragm lever and/or crank down the condenser and/or turn
down the intensity of the light.