MR-VP Reactions Pg.91-94 ( Not Done/still Need Some Results) Flashcards

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1
Q

MR-VP is an acronym for two separate tests:

A

Methyl Red and Vogues-Proskauer

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2
Q

These two tests are based on differences in:

A

Bacterial fermentative end products

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3
Q

The tests ere originally used to distinguish between:

A

Escherichia coli and Enterobacter aerogenes

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4
Q

These tests are now used to assist in the identification of many other species, primarily in:

A

The family Enterobacteriaceae

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5
Q

A single tube of broth medium containing ________ can be used for evaluation of both tests.

A

Glucose

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6
Q

Some bacteria (E. Coli) ferment the glucose and produce acids of such concentration and strength that the pH that the pH is lowered to ….

A

4.4 or less (MR test).

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7
Q

Other bacteria (E. Aerogenes) ferment the same carbohydrate and produce a neutral end product such as: ___________, detected in the V-P test.

A

Acetyl methyl carbinol (AMC)

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8
Q

Equation for methyl red test:

A

Enzyme pathway
Glucose————————->ATP+ Organic Acids

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9
Q

Equation for Voges-Proskauer test:

A

Enzyme Pathway
Glucose—————————> ATP+AMC+Organic Acids/Alcohols (Acetyl Methyl Carbinol)

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10
Q

Procedure: both tubes of E. Coli and E. Aerogenes are incubated at 37 degrees Celsius for how long?

A

2-3 days.

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11
Q

After incubation, in order to add the appropriate reagents required for each test, you will need to:

A

Aliquot each of the grown broth cultures into 2 separate clean test tubes.

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12
Q

How should the broth look after incubation?

A

Cloudy with growth

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13
Q

How may drops of methyl red indicator is added into the tube labeled MR?

A

5

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14
Q

What does a red color indicate?

A

The presence of a strong acid, pH 4.4 or lower, ex: organic acids.

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15
Q

What does a yellow color indicate?

A

A yellow, orange or gold color indicates the absence of strong acid pH 6.0 or higher.

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16
Q

For the Voges-Proskauer test, how many drops of VPA AND VPB are added to the VP tube?

A

8 drops each

17
Q

How long should the sample stand after the drops are added in?

A

Minimum of 20-30min. Do not agitate the tube.

18
Q

A ring or layer of what color at the top of the liquid indicates presence of AMC. What does any other color indicate?

A

RED COLOR
Any other color= negative reaction

19
Q

Results for MR test:

A

Medium: MRVP broth
Substrate:glucose
Reagents: methyl red
Positive end prod: ATP & organic acid
Positive appearance:red
Negative appearance: yellow and orange

20
Q

VP results:

A

Broth: MRVP broth
Substrate: glucose
Reagents: vp
POs. End prods.= ATP, organic acids, alcohol
POs. Appearance= dark red
Neg appearance= any color than red

21
Q

E. Aerogenes was what color

A

Yellow, negative

22
Q

E. Coli was what color

A

Red, positive