A blood agar plate is a common type of differential media. If there are different species of bacteria on a blood agar plate, what will the zones of clearance around the bacteria show you?

• A. The zones of clearance can differentiate between the type different species of bacteria.
• B. The zones of clearance will show you whether the bacterial species if an alpha or beta-hemolytic species.
• C. If a zone of clearance is not present, it shows that the bacterial species is not hemolytic.
• D. All of the above.

Answer: (D)

Verified step by step guidance

1. Understand that a blood agar plate is used to differentiate bacterial species based on their hemolytic properties.
2. Recognize that hemolysis refers to the breakdown of red blood cells, which can be observed as clear zones around bacterial colonies on blood agar.
3. Identify the types of hemolysis: alpha-hemolysis (partial hemolysis, greenish discoloration), beta-hemolysis (complete hemolysis, clear zone), and gamma-hemolysis (no hemolysis, no change).
4. Observe the zones of clearance around bacterial colonies: a clear zone indicates beta-hemolysis, a greenish zone indicates alpha-hemolysis, and no zone indicates gamma-hemolysis.
5. Conclude that the presence or absence of these zones helps differentiate between bacterial species, confirming that all the given statements are correct.