Microbiology: Phenylalanine Deaminase Test

The video tutorial explains the phenylalanine deaminase test, a biochemical test used to identify bacteria in the Enterobacteriaceae family, specifically Proteus and Providencia. The test detects the enzyme phenylalanine deaminase, which converts phenylalanine into phenyl pyruvic acid. The presence of this enzyme is indicated by a color change to green when ferric chloride is added. The video also demonstrates how to interpret positive and negative test results, with a green color indicating a positive result and no color change indicating a negative result.

Which two genera within the Enterobacteriaceae family are identified using the phenylalanine deaminase test?

• Shigella and Yersinia

• Klebsiella and Enterobacter

• Proteus and Providencia

• Escherichia and Salmonella

What is the role of phenylalanine deaminase in the biochemical test?

• It converts phenylalanine into ammonia.

• It uses molecular oxygen to convert phenylalanine into phenyl pyruvic acid.

• It synthesizes phenylalanine from pyruvic acid.

• It breaks down phenylalanine into glucose.

What indicates a positive result in the phenylalanine deaminase test?

• A red color change

• A green color change

• A blue color change

• No color change

What is the purpose of adding ferric chloride in the phenylalanine deaminase test?

• To neutralize the reaction

• To provide a nutrient source

• To react with phenyl pyruvic acid and cause a color change

• To sterilize the test environment

What does a negative result in the phenylalanine deaminase test indicate?

• Absence of phenylalanine deaminase

• Presence of Proteus or Providencia

• A green color change

• Presence of phenyl pyruvic acid