Question

1. The MR test is used to determine which of the following?
   • Mixed acid fermentation
   • Indole
   • Acetoine
   • Sulfur reduction
2. Select the tests that are part of the IMViC series
   • SIMs test
   • Phenol Red Broth
   • Citrate test
   • Urease test
   • MRVP
3. Which of the following can be determined using a SIMs test?
   • Fermentation of glucose
   • Sulfur reduction
   • Motility
   • Indole production
   • Mixed acid fermentation
4. Which of the following enzymes is responsible for indole production in the SIMs test?
   • Tryptophanase
   • Thiosulfate reductase
   • Citrate permease
   • Cystein desulfurase
5. The Vogues Proskauer test (VP test) detects the presence of products from the ________ pathway used by bacteria to convert pyruvate into 2,3 butanediol and acetoine.
   • Glycolytic
   • butylene glycol
   • tricarboxylic acid
   • fermentation
6. In order for an organism to give a positive result in an MR test, it must produce enough acid from fermentation to overcome a phosphate buffer.
   • True
   • False
7. The MRVP tests are inoculated as two separate broths.
   • True
   • False
8. Which of the following would be considered a positive result for an MR test and a negative result for the VP test?
   • No color change after addition of methyl red and a color change to red after addition of VPa and VPb
   • Color change to yellow after addition of methyl red and color change to copper after addition of VPa and VPb
   • Color change to yellow after addition of methyl red and color change to red after addition of VPa and VPb
   • Color change to red after addition of methyl red and no color change after addition of VPa and VPb reagents
9. What is the pH indicator in the citrate test?
   • Neutral red
   • Litmus
   • Bromothymol blue
   • Phenol red
10. The nitrogen source in citrate media is ________.
    • amino acids
    • sodium nitrate
    • ammonium phosphate
    • potassium nitrate
11. An organism capable of producing citrate permease (citrase) will cause the Simmons citrate media to turn ________.
    • Yellow
    • Red
    • Blue
    • Green

Answer 1

1 answer- Mixed acid fermentation .

The methyl red (MR ) test is done to determine the mixed acid fermentation. In mixed acid fermentation, fermentation of glucose occurs and as a result produced organic acids. The option -indole,Acetoin and sulfur reduction are the incorrect answers.

2.Citrate test

IMViC series consist of methyl red test,Voges-proskauer test, citrate utilization test and indole production test.Thus, the correct answer is citrate test. SIMs test,Phenol Red Broth,Urease test and MRVP are the wrong answers.

3.Sulfur reduction ,Indole production and Motility

The sulfur indole motility media helps in differentiating the members of enterobacteriaceae by the ability to reduce sulfur ,indole production and motility through the sulfur indole motility media agar.The fermentation of glucose and mixed acid fermentation can be determined by the methyl red (MR ).

4.Tryptophanase

The members of enterobacteriaceae secretes the enzyme tryptophanase which helps in hydrolysis of the tryptophan and produces the indole through the deamination reaction.The options -Thiosulfate reductase,Citrate permease and Cystein desulfurase are the wrong options because it is not involved in the hydrolysis of tryptophan and production of indol.