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Raoultella planticola on urea agar. The urease agar slant is used to measure an organism’s ability to produce urease, an enzyme capable to digesting urea in carbon dioxide and ammonia through hydrolysis. Because ammonia is alkaline, the media contains phenol red, an indicator that changes from orange to pink when a pH increases above 8.1.
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.
A frequent test done with LIA agar is the LIA slant. Here the LIA is solidified at an angle, then inoculated with bacteria by stabbing the agar to within 1/4 inch of the bottom of the tube and streaking the slant. The slant is then incubated at 35 °C for 18–24 hours. The results are scored as follows: purple slant/yellow butt = LSI Negative
Simmons’ agar can be bought from suppliers as ready-made powders or slants. A slant is prepared by adding the heated agar to a test tube and allowing it to solidify at a slanted angle. To transfer cells from a sample to the agar, a sterilized needle is used to select a distinct colony from the sample and to streak across the agar surface, as ...
Stab cultures are similar to agar plates, but are formed by solid agar in a test tube. Bacteria is introduced via an inoculation needle or a pipette tip being stabbed into the center of the agar. Bacteria grow in the punctured area. [ 11 ]
Urease activity was first identified in 1876 by Frédéric Alphonse Musculus as a soluble ferment. [4] In 1926, James B. Sumner, showed that urease is a protein by examining its crystallized form. [5]
This rod-shaped bacterium has the ability to produce high levels of urease, which hydrolyzes urea to ammonia (NH 3), so makes the urine more alkaline. Prolonged increased alkalinity can lead to the formation of crystals of struvite , calcium carbonate , and/or apatite , which can result in struvite kidney stones.
Bromothymol blue was added in order to reduce false positives. The citrate agar is green before inoculation, and turns blue, because of BTB as a positive test indicator, meaning citrate is utilized. The test is also prepared on a slant to maximize bacterial growth for an even better indication of the use of citrate.