Nitrate Reduction Test Flashcards

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Questions and Answers

What enzyme reduces nitrate to nitrite?

Nitrate reductase

Is NO3, nitrate?

True

What is denitrification?

Process by which enzymes convert nitrite (NO2) to nitric oxide (NO), nitrous oxide (N2O), and nitrogen gas (N2)

The medium used in the Nitrate Reduction test is _________________________________?

Nitrate Broth Signup and view all the answers

NO2 is __________________?

Nitrite Signup and view all the answers

A positive test for nitrate reduction is indicated by a __________________?

Red color Signup and view all the answers

A positive test for denitrification is indicated by a ______________________?

Bubbling in the Durham Tube Signup and view all the answers

A positive test for no nitrate reduction is indicated by a __________________?

Red color after the addition of zinc dust after reagents A and B were added Signup and view all the answers

What purpose does reducing nitrate to nitrite serve a microorganism?

The breakdown of nitrate to nitrite is important for the microorganism because nitrogen is needed as a source for protein synthesis as well as DNA synthesis. Signup and view all the answers

What are the test reagents for the Nitrate test?

<ol> <li>N, N-dimethyl-alpha-naphthylamine 2. 5N acetic acid 3. Sulfanilic acid</li> </ol> Signup and view all the answers

The substrate in this test is_, the enzyme being tested for is, and the end product of a positive nitrate reduction test is__________?

<ol> <li>Nitrate 2. Nitrate reductase 3. Nitrite</li> </ol> Signup and view all the answers

What is the end product of denitrification?

Nitric oxide (NO), Nitrous oxide (N2O), and Nitrogen gas (N2) Signup and view all the answers

What does Nitrate A and B react with to produce a red color?

Nitrate A and Nitrate B react with Nitrous acid to produce a red color Signup and view all the answers

After adding Nitrate A and Nitrate B, a color indicates that the microorganism was able to nitrate to ________?

<ol> <li>red 2. reduce 3. nitrite</li> </ol> Signup and view all the answers

What is the end product of nitrate reduction?

Nitrite Signup and view all the answers

A microorganism that is able to degrade nitrate to nitrite is able to conduct ___________________________ respiration?

Anaerobic respiration Signup and view all the answers

We are testing for a microorganism's ability to conduct _ by seeing if it is able to nitrate to _________?

<ol> <li>nitrate reduction 2. reduce 3. nitrite</li> </ol> Signup and view all the answers

After the addition of Nitrate A and B, a red color does not form. What could be occurring?

Nitrate either was not reduced or was reduced to other nitrogenous compounds Signup and view all the answers

The electron acceptor in anaerobic respiration is _______________________?

An inorganic molecule other than oxygen Signup and view all the answers

After the addition of Nitrate A and B, a red color does not form. Then zinc is added; if a red color forms this indicates that the microorganism could not _ nitrate to nitrite? What did the zinc do? The zinc would be called a ______?

<ol> <li>reduce 2. the zinc catalyzed the reaction by reacting with the nitrate; therefore, if the microorganisms turn red this time, it was due to zinc causing the color change.</li> </ol> Signup and view all the answers

After the addition of Nitrate A and B, a red color does not form. Then zinc is added and still a red color does not form. What did the microorganism do?

The microorganism converted the nitrate to something else other than nitrite, for example N2; therefore, there is no nitrate for the zinc to react with and it remains colorless. Signup and view all the answers

What do sulfanilic acid and naphthylamine react with that results in a color change to red?

Nitrate is reduced to nitrite Signup and view all the answers

Study Notes

Nitrate Reduction Test Overview

Nitrate reductase is the enzyme responsible for reducing nitrate (NO3) to nitrite (NO2).
Nitrate (NO3) is a nitrogen source for microorganisms.
Nitrate Reduction Test involves assessing the ability to convert nitrate to nitrite, revealing insights into microbial respiration.

Key Concepts in Nitrate Reduction

Denitrification is the biological process where nitrite is converted into nitric oxide (NO), nitrous oxide (N2O), and nitrogen gas (N2).
The Nitrate Broth is the medium used for the test and contains beef extracts, peptone, and potassium nitrate.

Test Indicators

A red color indicates a positive result for nitrate reduction, confirming the conversion to nitrite.
Bubbling in the Durham Tube signifies a positive test for denitrification.
If a red color appears after adding zinc dust (following reagents A and B), it indicates no prior reduction of nitrate to nitrite occurred.

Importance of Nitrate Reduction

Microorganisms utilize the reduction of nitrate to nitrite for nitrogen, essential for protein and DNA synthesis.
Anaerobic respiration involves using an inorganic electron acceptor other than oxygen.

Test Reagents and Reactions

The reagents used in the nitrate reduction test are sulfanilic acid, N,N-dimethyl-alpha-naphthylamine, and 5N acetic acid.
A red color forms when reagents A and B react with nitrous acid, resulting in a color change.

Outcomes and Interpretations

If no color change occurs after adding reagents A and B, nitrate may not have been reduced or was converted to other nitrogenous compounds.
Zinc, if added after no color change, confirms whether the nitrate was reduced to nitrite or transformed into other compounds. A red color indicates no reduction took place.
Unable to produce a red color after adding zinc suggests conversion of nitrate to a different form (e.g., N2), indicating denitrification.

Conclusion

The Nitrate Reduction Test evaluates a microorganism's ability to conduct nitrate reduction and denitrification, crucial for understanding nitrogen cycling and anaerobic respiration processes.

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Description

This quiz covers key concepts related to the Nitrate Reduction Test, including the role of enzymes and denitrification processes. Perfect for students studying microbiology and environmental science. Test your knowledge and reinforce your learning!