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Oxidative/fermentation glucose test (OF glucose test) is a biological technique. It was developed in 1953 by Hugh and Leifson to be utilized in microbiology to determine the way a microorganism metabolizes a carbohydrate such as glucose (dextrose). [ 1 ]
Inoculate a tube of glucose phosphate broth with a pure inoculum of test organism and incubate at 35 °C for 24 hours. To 1 mL of this broth add 0.6 mL of 5% α-Naphthol followed by 0.2 mL of 40% KOH. Shake the tube gently to expose the medium to atmospheric oxygen and allow the tube to remain undisturbed for 10–15 minutes.
The TSI slant is a test tube that contains agar, a pH-sensitive dye , 1% lactose, 1% sucrose, 0.1% glucose, [2] and sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate. All of these ingredients are mixed together, heated to sterility, and allowed to solidify in the test tube at a slanted angle.
The solution remaining yellow (pH = 6.2 or above) indicates a negative test, meaning the butanediol fermentation is used. The VP test uses alpha-naphthol and potassium hydroxide to test for the presence of acetylmethylcarbinol (acetoin), an intermediate of the 2,3-butanediol fermentation pathway. After adding both reagents, the tube is shaken ...
Voges–Proskauer / ˈ f oʊ ɡ ə s ˈ p r ɒ s k aʊ. ər / or VP is a test used to detect acetoin in a bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth, which is a glucose-phosphate broth that has been inoculated with bacteria. A cherry red color indicates a positive ...
They are simply smaller test tubes inserted upside down in another test tube so they are freely movable. The culture media to be tested is then added to the larger tube and sterilized, which also eliminates the initial air gap produced when the tube is inserted upside down. The culture media typically contains a single substance to be tested ...
A level below 5.6 mmol/L (100 mg/dL) 10–16 hours without eating is normal. 5.6–6 mmol/L (100–109 mg/dL) may indicate prediabetes and oral glucose tolerance test (OGTT) should be offered to high-risk individuals (old people, those with high blood pressure etc.). 6.1–6.9 mmol/L (110–125 mg/dL) means OGTT should be offered even if other ...
Sugar fermentation lowers the pH and the phenol red indicator registers this by changing to yellow. Most gut bacteria, including Salmonella , can ferment the sugar xylose to produce acid; Shigella colonies cannot do this and therefore remain red.