Biochemical Tests Test Questions – Flashcards
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|MR of MR-VP|
1.) Add Methyl red (5 drops) and figer vortex
2.)Methyl red pH indicator is red at a pH below 4.5. therefore a red is a positive methyl red test and yellow is a negative.
|VP of MR-VP|
1.) Finger vortex and remove 1 ml of solution of broth.
2.) add 12 drops of Alpha-Naphthol and 8 drops of KOH
3.) Wait 20 minutes and then finger vortex.
4.) Cranberry color formation indicates a positive voges- prosakauer
a coke or root beer color with bubbles is negative
If glucose broken down more neutral such as acetoin production
|Ornithine and Lysine Decarboxylases|
Amino acids that is broken down by decarboxylase enzymes
1.) Positive test is a deep purple (basic pH)
A negative test is yellow (acid pH)
Does organism produce urease. yes- urease is broken down
Basic- Bright Pink
Phenol Red indicator
How to Perform Test: Inoculate Tryptone broth with inoculating loop.
Property it tests for: This test is performed to help differentiate species of the family Enterobacteriaceae. It tests for the bacteria species’ ability to produce indole. Bacteria use an enzyme, tryptophanase to break down the amino acid, tryptophan, which makes by-products, of which, indole is one.
Media and Reagents Used: Tryptone broth contains tryptophan. Kovac’s reagent—contains hydrochloric acid, dimethylaminobenzaldehyde, and amyl alcohol—yellow in color.
Reading Results: Kovac’s reagent reacts with indole and creates a red color at the top part of the test tube.
1.) Inoculate slant
2.) To find if they use citrate for sole source of carbon and ammonia as sole nitrogen source
3.)Simmon’s Citrate Agar contains sodium citrate (carbon source), ammonium ion (nitrogen source), & pH indicator—bromthymol blue.
3.) A + result is blue (meaning the bacteria metabolised citrate and produced an acid end product) and a – result remains green
How to Perform Test: Stab SIM media with inoculating needle.
Property it tests for: This test is used to help differentiate species of the family Enterobacteriaceae. This test is used to determine the ability to reduce sulfur into H2S.
Media and Reagents Used: SIM media contains the sulfur containing amino acid, cysteine, sodium thiosulfate, & peptonized iron or ferrous sulfate.
Reading Results: H2S will react with the iron or ferrous sulfate and produce a black precipitate. A positive result has a black precipitate present and a negative result has no black precipitate.
How to Perform Test: Stab motility media with inoculating needle.
Property it tests for: This test is done to help differentiate species of bacteria that are motile.
Media and Reagents Used: Motility media contains tryptose, sodium chloride, agar, and a color indicator.
Reading Results: If bacteria is motile, there will be growth going out away from the stab line, and test is positive. If bacteria is not motile, there will only be growth along the stab line. A colored indicator can be used to make the results easier to see.
- Does organism produce amylase? Yes=starch is gone No=starch is present
-add indicator (gram's iodine)
-clear zone means positive, dark color complex mena negative
1.) plate divided down middle...each organism on each side.
2.) add gram's iodine.
3.) if clear positive (starch gone) if blue negative (starch present)
4.) Does it produce amylase
Does the organism produce gelatinase.
If positive liquid when cold
If negative solid
Does the organism utilize that sugar?
yes= acid- yellow
no=basic- bright pink
no- neutral- orange red
Durham tube. Does it produce gas?
liquid out of durham tube yes
full durham tube no
Glucose gas= +
Does the organism produce phenylaline deaminase?
change to green yes
no change- negative
Does the organism produce DNASE?
Yes DNA broken down and creates a large clearing of metyl green.
Negative no clearing