Page 117 - MNUmicrobiology practical 2025

General Microbiology & Immunology (PM 401) second level Semester 4 2024/2025

10- Urease production

• Purpose: To detect production of urease

• Media: Urea broth/agar

• Reagents/indicators: Phenol Red

• Mechanism/reactions: Urease hydrolyzes urea to ammonia and

carbon dioxide. Ammonia increases the pH of the culture causing

the phenol red to go from yellow to bright pink.

• Directions: Inoculate urea broth and incubate for 24 – 48 h.

• Interpretation:

(+) = Red or bright pink color (pH > 8.4)
(-) = Yellow color (pH < 6)

11- Hemolysin production
• Purpose:

To test the ability of the microorganism to produce exoenzymes hemolysin that has

destructive effect on the blood cells

• Some microorganisms completely destroy the blood cells resulting in complete

hemolysis of the surrounding area known as B-hemolysis

• Other microorganism partially hydrolysis hemoglobin resulting in greenish area

known as Alpha hemolysis.

• Organisms don’t produce hydrolysis and

have no effect on the red blood cells are

gamma-hemolysis.

General Microbiology & Immunology (PM 401) Practical note Page 106