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20 terms

Micro Lab Quiz 10

STUDY
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What does the TSI test stand for?
Triple Sugar Iron
What is TSI composed of?
0.1% Glucose + 1.0% Lactose + 1.0% Sucrose + Phenol Red + Sodium Thiosulfate + Ferrous Ammonium Sulfate
What kinds of tests is the TSI test a mixture of?
Carbohydrate fermentation tests (involving sugars and phenol red) and the S in SIM test (testing for liberation of thiosulfate)
Liberation of Thiosulfate in the area of the TSI (as seen in the SIM test) produces what?
H2S
When doing the carbohydrate fermentation of the slant, what possible results would you have if you have both a yellow slant and a yellow butt. What does this mean was NOT produced?
either 1) lactose was fermented, 2) sucrose was fermented, 3) lactose & sucrose were fermented, or 4) lactose & sucrose & glucose were fermented; indicates that the fermentation of ONLY glucose was not present.
During the carbohydrate fermentation, what color(s) indicate that only glucose was fermented? What is this due to?
yellow butt and red slant; because by fermenting only 1/10th of a percent of glucose (all that was in there), enough acid isn't produced to turn all of phenol from red to yellow
What is another reason that the butt of the slant is being stabbed? What will you expect to see and why?
to test for gas production; because there is no durham tube to catch the gas, if CO2 is released, you will have "Agar Disruption"
How do we determine if hydrogen sulfide (H2S) gas reacted with Ferrous Ammonium Sulfate?
produce ferrous sulfide is produced which is a black ppt
yellow slant + black butt =
more than just glucose fermented and ferrous sulfide was produced
red slant + yellow butt =
H2S production and no gas production
yellow slant/butt + agar disruption =
no H2S formation, gas production with more than just glucose fermented
yellow slant + yellow butt =
gas production, no H2S, both slant and butt are acid but more than just glucose fermented.
Which types of bacteria will we be inoculating with during the TSI experiment?
1 slant with E. coli and 1 slant with Proteus
What is it that gives milk its white color?
Casein protein
When doing the casein test, with what and how will the streak plate be inoculated?
line drawn down middle of back; one side labeled bacillus and one side labeled E. coli; streak once with each on their respective sides
During tho experiment, release of CO2 gas proves what?
fermentation of sugars
Some bacteria can breakdown casein protein by use of what enzyme?
proteases
The breakdown of casein is also known as what?
proteolysis
What will a positive Casein Hydrolysis test look like?
zone of proteolysis around the streak that is clear-ish
How was the agar plate made? What is specifically important and why?
Used plate count agar, mixed up, then add 10% of skim milk; % of skim milk is important: enough to be milky cloudy, but can't have so much that it dilutes agar and keeps it from setting up (Balances amount is about 10%)