Urea Slants
What pH indicator is added in this medium?
Phenol red
What is the action of urease?
-Urea, the primary nitrogenous waste in the urine of many land animals (including mammals), is hydrolyzed to ammonia and carbon dioxide by bacteria possessing the enzyme urease. -Urease catalyzes the hydrolysis of urea into ammonia and carbon dioxide.
What is the color of the pH indicator at acid pH?
-Yellow or orange below pH 8.4 -Phenol red is yellow or orange below pH 8.4
What indicates a positive test for urea test?
-Pink color in the medium indicates a rapid urease-positive organism. -Pink result indicates rapid urea hydrolysis; strong urease production. Positive test for urea: pink color -On the other hand, orange or yellow indicate no urea hydrolysis; urease is absent or not produced in enough quantity to produce results in 24 hours.
What is the color of the pH indicator at basic pH?
-Red or pink above pH 8.4 -Phenol red is red or pink above pH 8.4
What are the uses?
-This test is used to differentiate organisms based on their ability to hydrolyze urea with the enzyme urease. -Urinary tract pathogens from the genus Proteus may be distinguished from other enteric bacteria by their rapid urease activity. -It is also used in identifying Helicobacter pylori, which is associated with gastric ulcers, as well as stomach cancer.
Explain the reason for the color change.
Urea hydrolysis produces ammonia, which raises the pH in the medium and turns the pH indicator pink. -The color indicates whether positive or negative.
