determine if an org contains flagella in order to move
Motility test directions
use needle-want straight as can get
-insert the needle all the way to the bottom of the tube and gently remove it
-remove as straight as possible as well
What do you do if you do move your needle?
make a note of which way (use your label as a reference) you moved it, as you can compare your results easier this way
What happens to the organisms as you move the needle through the media?
they become detached
sulfur, indole, motility
When you read your results for the SIM test what do you want to record first?
read the sulfur and motility first
iron salts in media react with H2S to form a dark precipitate of iron sulfide, which is positive
Use the location of the sulfur to help determine what?
if the organism is motile
-if you cannot see through the media it is also motile
Formulas for Sulfur test
Cystenine (cystenine desulfurase) > NH(3) and Pyruvate and H(2)S
H(2)S> FeSO(4) > FeSH(2)SO(4) (black precipitate)
Positive Sulfur test: color and example
Negative: ex Sulfur Test
I guess no black is neg
Motility: what do you look for?
look for cloudiness throughout media and away from the stab line
Positive for motility
(note: some microbes have a light colony color so you need to remember how clear your uninoculated media looked)
Positive motility ex
Negative Motility ex
Indole test detects what?
detects if organism produces tryptophanase
reduced tryptophan down to indole, pyruvic acid, and ammonia
What do you add to tube to test for typtophanase? Why do you add this?
-indole is not used in any further chemical pathways so can use it to test
What happens when you add Kovac's reagent?
Kovac's reagent reacts with the indole to produce a bright red color on top of the media-positive
Positive result for Indole test and ex orgs
bright red color on top
Ex: Escherichia coli
Negative result for Indole test and ex orgs
no color change is negative
How many drops of Kovac's reagent do you add? How long will it take for a color change?
add ten drops to deep tube
look for a color change within one minute
Formula for Indole test
Tryptophan (tryptophanase) > NH(3) and Pyruvate and Indole