What does a positive citrate utilization test?

What does a positive citrate utilization test?

A positive reaction shows that the organism can use citrate but not necessarily as the sole carbon source.

What are the products of citrate utilization test?

Principle of citrate utilization test: The citrase enzyme hydrolyses the citrate to form oxaloacetic acid and acetic acid. The test organism is cultured in a medium which contains sodium citrate and indicator bromothymol blue.

What is the end product of citrate test?

The citrate test identifies the use of citrate as a sole carbon source, since there are no other nutrients in this medium. The basic end products (carbonates, bicarbonates, and ammonium hydroxide) will cause the brom thymol blue indicator in the medium to turn from forest green to royal blue.

Is Klebsiella citrate positive?

Klebsiella pneumoniae and Proteus mirabilis are examples of citrate positive organisms. Escherichia coli and Shigella dysenteriae are citrate negative.

What does a positive indole test mean?

Like many biochemical tests on bacteria, results of an indole test are indicated by a change in color following a reaction with an added reagent. A positive result is shown by the presence of a red or red-violet color in the surface alcohol layer of the broth. A negative result appears yellow.

What is the purpose of citrate utilization test what are the products of this reaction and how are these products detected?

Citrate utilization test is used to determine the ability of bacteria to utilize sodium citrate as its only carbon source and inorganic ammonium dihydrogen phosphate (NH4H2PO4) as the sole nitrogen source.

What does Simmons citrate test for?

Simmons citrate agar tests the ability of organisms to utilize citrate as a carbon source. Simmons citrate agar contains sodium citrate as the sole source of carbon, ammonium dihydrogen phosphate as the sole source of nitrogen, other nutrients, and the pH indicator bromthymol blue.

What does citrate test indicate?

The citrate test detects the ability of an organism to use citrate as the sole source of carbon and energy.

How do you read a citrate test?

At pH 7.5 or above, bromthymol blue turns royal blue. At a neutral pH, bromthymol blue is green, as evidenced by the uninoculated media. If the medium turns blue, the organism is citrate positive. If there is no color change, the organism is citrate negative.

What color is a positive citrate test?

The citrate utilization test is used as part of the IMViC series for differentiating among the Enterobacteriaceae . The Simmons citrate slant is normally a light forest green in color. A positive citrate reaction results in a change in color of the bromthymol blue indicator in the media to a deep royal blue.

What is the purpose of the citrate test?

The citrate test detects the ability of an organism to use citrate as the sole source of carbon and energy.

What is citrate agar test?

Citrate agar is used to test an organism’s ability to utilize citrate as a source of energy. The medium contains citrate as the sole carbon source and inorganic ammonium salts ( NH4H2PO4 ) as the sole source of nitrogen.

What is citrate test in microbiology?

Citrate test. The citrate test detects the ability of an organism to use citrate as the sole source of carbon and energy.