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 _________________________________?
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NO2 is __________________?
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A positive test for nitrate reduction is indicated by a __________________?
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A positive test for denitrification is indicated by a ______________________?
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A positive test for no nitrate reduction is indicated by a __________________?
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What purpose does reducing nitrate to nitrite serve a microorganism?
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What are the test reagents for the Nitrate test?
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The substrate in this test is_______________________, the enzyme being tested for is______________________, and the end product of a positive nitrate reduction test is______________________________?
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What is the end product of denitrification?
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What does Nitrate A and B react with to produce a red color?
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After adding Nitrate A and Nitrate B, a ____________ color indicates that the microorganism was able to __________________ nitrate to __________________?
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What is the end product of nitrate reduction?
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A microorganism that is able to degrade nitrate to nitrite is able to conduct ___________________________ respiration?
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We are testing for a microorganism's ability to conduct ___________________ ________________________ by seeing if it is able to ______________________ nitrate to _________________________?
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After the addition of Nitrate A and B, a red color does not form. What could be occurring?
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The electron acceptor in anaerobic respiration is _______________________?
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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 ________________________?
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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?
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What do sulfanilic acid and naphthylamine react with that results in a color change to red?
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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!
