5-4 MR-VP test STUDY******
What are the chemical names for VP A and VP B
Napthol and postassium hydroxide
2,3 butanediol fermentation converts acids into
Alcohol a more neutral pH
Rate of color develope depends on
Amount of acetoin
This test is used to differentiate what family ? Significance ?
Enterobacteriaceae family used to differentiate them
Ph indicator for MR test portion is it in media ? What end product does it indicate ?
Methylene red, no it's an added chemical indicates lactic acid, acetic acid, formic acid
Enterobacteriaceae is also referred to as
Enterics
What's the second portion of this test called what are we testing for
VP test 2,3 butanediol fermentation of glucose
What test is VP A and B added to and why
VP, they help with the visuals
What PH and color are we looking for in MR that indicates a positive
Very acidic 4.4 and below we will get a red cherry color
What are the end products of this VP test ?
Alcohol (2,3 butanediol)
Why can we pipette from the same test tube when making both MR and VP tests tubes
Glucose is the starting material for both tests, they both start the same way.
Which sugar is included in the broth you inoculated, why is it there ?
Glucose, for fermentation
3 steps of fermentation
Glucose——glycolysis——-pyruvate——end products acid, alcohol, gas.
Time Development of rate of color depends on for VP
Amount of acetoin
What are the 3 main acid end products of MR test and VP
Acetic acid, formic acid "bee venom",lactic "working out acid" ,
What are we testing for in the first portion of this test
Mixed acid fermentation
Methylene red slightly acidic will look ? Is this positive ?
Orange, this is negative or inconclusive
What chemicals do we add to VP
VP A= tags acetoin intermediate and VP B= catalyze color change
What's a negative for VP
Rusty brown negative for metabolizing the 3 acids for glucose fermentation
What does IMViC stand for?
Indole, Methyl Red, Vogues Proskauer, and Citrate
Why are bacteria usually either positive for the methyl red test or voges proskaver test but not both
MR organisms may not be able to metabolize acids, and VP acids won't be around because they were converted to alcohol.
What happens to the PH in an MR positive versus VP positive
MR ph is very acidic and is more stabile, VP acids aren't and become more neutral because of 2,3 butanediol fermentation end products
For the MR portion what end product from fermentation are we looking for
Acid
In VP side we are testing for ?
Alcohol
What's a positive for VP look like
Red positive for acetoin/Alcohol 3 acids were metabolized
How many tests does this experiment contain
2
What kind of experiment is this ?
Fermentation organisms are utilizing glucose
Which test tests for mixed acid fermentation and 5 end products ?
Methyl red test, lacticacid, acetic acid, formic acid, ethanol, carbon dioxide gas
How do we get to that alcohol end product of VP
If organism is capable of 2,3 butanediol fermentation (metabolizing acids) the 3 same acids will be made but then they will go through butanediol pathway and metabolized into acetoin the intermediate, then finally 2,3 butanediol alcohol
What does an orange tube mean ?
Negative or inconclusive
Why must we incubate our test for 5 days
Because acids a continually being produced, acetoin may need time to develope.
What Is the purpose of this test
To see is organism is capable of mixed acid fermentation (methylene red test ) or 2,3 butanediol fermentation (Voges-Proskauer test) by using glucose in our MR-VP broth.
Is positive for mix acid fermentation what will happen to PH
It will drop a lot, very acidic.
Media and ingredients 3
MR VP broth, peptone, buffer, and glucose
Methylene red at neutral, color and pH, is it positive or negative ?
Yellow pH at 6.2, negative
