Is Proteus mirabilis phenylalanine deaminase positive?
When 10% ferric chloride is added to phenylalanine deaminase medium inoculated with Proteus mirabilis, the presence of phenylpyruvic acid causes the media to turn dark green. This is a positive result.
How do you recognize a positive result in phenylalanine agar?
The phenylpyruvic acid is detected by adding a few drops of 10% ferric chloride which acts as a chelating agent ; a green colored complex is formed between these two compounds indicating a positive test. If the medium remains a straw color, the organism is negative for phenylalanine deaminase production.
What color indicates a positive result for the phenylalanine deaminase test?
green color
Interpretation of Results: A green color appearing within 1-5 minutes is a positive result for the production of phenylalanine deaminase. No color change indicates a negative result.
Which species of bacteria produced the enzyme phenylalanine deaminase?
The genera Proteus, Providencia, and Morganella are related members of the Enterobacteriaceae that are lactose negative, are motile, and produce phenylalanine deaminase. There are several species of Proteus, but Proteus mirabilis and Proteus vulgaris account for the vast majority of clinical Proteus isolates.
What is the phenylalanine test used for?
Serum phenylalanine screening is a blood test to look for signs of the disease phenylketonuria (PKU). The test detects abnormally high levels of an amino acid called phenylalanine.
When a phenylalanine is Deaminated what substance is produced?
Deamination of l-phenylalanine produces trans-cinnamic acid (CA) which is further hydroxylated in the para position to produce pHCA. However, when tyrosine is used as the substrate, trans-pHCA is produced in one step.
What is a normal phenylalanine level?
The acceptable range of plasma phenylalanine levels during treatment is 2 to 10 mg per dL (121 to 605 μmol per L).
What is phenylalanine made from?
L-phenylalanine is an essential amino acid. It is the only form of phenylalanine found in proteins. Major dietary sources of L-phenylalanine include meat, fish, eggs, cheese, and milk.
What does too much phenylalanine do to the body?
Nutrition and healthy eating Phenylalanine can cause intellectual disabilities, brain damage, seizures and other problems in people with PKU . Phenylalanine occurs naturally in many protein-rich foods, such as milk, eggs and meat. Phenylalanine is also sold as a dietary supplement.
What is a high level of phenylalanine?
People with untreated classic PKU have levels of phenylalanine high enough to cause severe brain damage and other serious health problems. Mutations in the PAH gene that allow the enzyme to retain some activity result in milder versions of this condition, such as variant PKU or non-PKU hyperphenylalaninemia.
What do you need to know about phenylalanine deaminase test?
Phenylalanine Deaminase Test. Phenylalanine agar, also known as phenylalanine deaminase medium, contains nutrients and DL-phenylalanine. It is used to differentiate members of the genera Proteus, Morganella (which were originally classified under the genus Proteus ), and Providencia from other Enterobacteriaceae.
What makes Proteus mirabilis negative for phenylalanine deaminase?
If the medium remains a straw color, the organism is negative for phenylalanine deaminase production. When 10% ferric chloride is added to phenylalanine deaminase medium inoculated with Proteus mirabilis, the presence of phenylpyruvic acid causes the media to turn dark green.
When to inoculate phenylalanine slant with a test organism?
Inoculate the phenylalanine slant (with a loop on the surface) with a test organism. Note: If you are using the test medium i.e. phenylalanine agar for the first time use positive (Proteus vulgaris) and negative control (Escherichia coli) to check the efficacy of the test medium.
What happens to phenylalanine deaminase After incubation?
After incubation, 10% ferric chloride is added to the media; if phenylpyruvic acid was produced, it will react with the ferric chloride and turn dark green. If the medium remains a straw color, the organism is negative for phenylalanine deaminase production.