What is the purpose of Simmons Citrate test quizlet?
What is the purpose of Simmons Citrate test quizlet?
The citrate test determines if an MO uses citrate as a sole source of carbon.
What does the Simmons citrate test demonstrate?
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 it mean if the citrate agar is blue after incubation quizlet?
If bacteria use citrate, they will turn the agar from green to blue due to a rise in alkalinity; no reagents will be required. In the citrate utilization test, citrate metabolism decreases the pH, which results in a yellowing of the blue agar to generate a green positive color.
What does a positive result indicate in the citrate test quizlet?
A positive result is color change from green to blue and/or growth. This means that citrate is utilized. Bacteria that use citrate converts the ammonium which alkalizes the agar. Therefore the dye changes from pH of 6.9 to 7.6 (acidic to alkaline) and the green dye indicates the pH going up by its color change to blue.
What is the substrate for citrate test?
What is the substrate for the Citrate Agar? An enzyme called citrase will catabolize the citrate into oxaloacetic acid and acetic acid.
What 2 substrates are involved in the citrate test?
Bacteria are inoculated on a medium containing sodium citrate and a pH indicator such as bromothymol blue. The medium also contains inorganic ammonium salts, which are utilized as sole source of nitrogen. Use of citrate involves the enzyme citrase, which breaks down citrate to oxaloacetate and acetate.
What is the aim of citrate test?
The citrate test detects the ability of an organism to use citrate as the sole source of carbon and energy.
Why citrate test is done?
Citrate testing is used to determine the ability of the bacteria to use sodium citrate as the only source of carbon and inorganic ammonium hydrogen phosphate (NH4H2PO4) as a source of nitrogen. The citrate utilization test is possible only if the organisms are capable of fermenting citrate.
What does a positive results indicate in the citrate test?
A positive reaction shows that the organism can use citrate but not necessarily as the sole carbon source.
Why does a positive Simmons citrate agar result in the slant turning blue?
Growth is indicative of utilization of citrate, an intermediate metabolite in the Krebs cycle. When the bacteria metabolize citrate, the ammonium salts are broken down to ammonia, which increases alkalinity. The shift in pH turns the bromthymol blue indicator in the medium from green to blue above pH 7.6.
What type of indicator does the citrate test use quizlet?
-we can detect the use of citrate using a citrate agar slant containing sodium citrate and the pH indicator bromothymol blue.
How do you test for citrate?
Procedure of Citrate Utilization Test
- Streak the slant back and forth with a light inoculum picked from the center of a well-isolated colony.
- Incubate aerobically at 35 to 37 C for up to 4-7 days.
- Observe a color change from green to blue along the slant.
What is the principle of Simmons citrate agar test?
In this method, if the test organism started to utilize the citrate for carbon and energy sources, it will grow on Simmons citrate agar. As a result, it will lead to a rise in pH of the medium, and a pH indicator changes color. Indole test – Principle, Procedure, Uses.
What happens when citrate is added to bacteria?
Once citrate enters into the bacterium, it’s started to converted into pyruvic acid and CO2. Simmons citrate test performed in slants, because O2 is necessary for citrate utilization. In this method, if the test organism started to utilize the citrate for carbon and energy sources, it will grow on Simmons citrate agar.
What happens when you add ammonium salts to a citrate test?
On the other side, the bacteria started to breakdown the ammonium salts into ammonia, as a result, it increases the alkalinity of medium. This raises the pH, turns the pH indicator to a blue color, and represents a positive citrate test, absence of a color change is a negative citrate test.
What is citrate agar used for?
Simmons’ citrate agar is a type of selective and differential medium. Which is used for the study of those organisms that have the ability to use citrate as a sole carbon source and ammonium ions as the sole nitrogen source.
