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Simmons citrate agar is a differential agar used to determine if a sample bacteria can utilize citrate as its only carbon source. The agar is initially a green color due to the bromo thymol blue pH indicator in it. If a bacteria uses the citrate, the by-products are ammonia and ammonium hydroxide both of which will alkalize the agar and increase the pH to the point of changing the indicator's color to blue, so the whole agar turns from green to blue.
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Why would a citrate-positive organism might not produce a color change in the simmons citrate agar?
bc im incomplete incubation time.
What is the result of citrate test for bacillus licheniformis?
The result is the initial green color of the Simmons Citrate Agar turning blue; generating a positive indication that the organism does indeed utilize citrate as the sole source of carbon and energy.
Why the slant portion is blue but the butt remains green at the microorganism grows on Simmon's citrate agar?
Fermenting citrate
If an organism is able to convert the sodium citrate in simmons citrate agar to pyruvate what are some possible reasons why an organism might ferment rather than metabolize it oxidatively in the Krebs?
Citrate, a Krebs cycle (i.e., TCA cycle or citric acid cycle) intermediate, is generated by many bacteria; however, utilization of exogenous citrate requires the presence of citrate transport proteins (permeases). Upon uptake by the cell, citrate is cleaved by citrate lyase to oxaloacetate and acetate. The oxaloacetate is then metabolized to pyruvate and CO2.
WHY IS NITROGEN SUPPLIED AS AMMONIUM SALTS (SPECIFICALLY) RATHER THAN AS AMINO ACIDS IN SIMMONS CITRATE AGAR?
If amino acids were used they would not produce the same degree of pH change that results in color change of the indicator.
What gram negative facultative anaerobic bacteria are lipase negative and Simmons citrate negative?
E. Coli
Home come E.coli can't grow on Simmons Citrate Media?
Because it cannot utilize citrate as the sole carbon source and/or they cannot utilize ammonium ions as the sole nitrogen source.
If the bacteria can not use citrate what will the results be in the citrate agar test?
If bacterium cannot use glucose the fermentation tube will stay the same color. Gas may also occur inside the fermentation tube.
Why pH of Simmon's citrate agar increase if citrate is utilized?
This is due to the production of oxalacetic acid and acetate, when the enzyme citrase acts on the citrate. the oxalacetic acid and acetate is enzymatically converted to pyruvic acid and carbon dioxide. the carbon dioxide combines with sodium and water forming sodium carbonate which in turns makes the medium alkaline.
Why is the citrate test carried out on an agar slope rather than a broth?
Background:Simmons' Citrate Agar is a defined, selective medium that tests for an organism's ability to use citrate as a sole carbon source and ammonium ions as the sole nitrogen source.The medium contains citrate, ammonium ions, and other inorganic ions needed for growth.It also contains bromothymol blue, a pH indicator. Bromothymol blue is green at pH below 6.9, and then turns blue at a pH of 7.6 or greater.SO:Sometimes, it is possible to detect growth on the citrate slant without the accompanying color change to blue. This is most likely due to insufficient incubation. Either a combination of blue color and growth or growth alone without the blue color should be scored as a positive for the citrate use test.
Is Salmonella-Shigella Agar selective or differential?
Blood agar is a differential media since you can differentiate between different organisms based on the colony appearance. In a blood agar you are looking for hemolysis.
Agar agar grain found in Germany?
Agar, or agar-agar, is not a grain, but rather an extract of seaweed. Agar translates to German as Agar-Agar Try whole- or health-food stores
