Multiple Choice
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?
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10. Dynamics of Microbial Growth
Differential Media
Multiple Choice
Streptococcus pneumoniae is an alpha-hemolytic bacterial species. If Streptococcus pneumoniae is grown on a blood agar plate, what characteristics will the zone of clearance for this species have?
A
The zone of clearance will be large and bright yellow in color.
B
The zone of clearance will be small and a greenish color.
C
This bacterial species will show no zone of clearance on a blood agar plate.
Verified step by step guidance1
Understand the concept of hemolysis: Hemolysis refers to the breakdown of red blood cells, and different bacteria exhibit different types of hemolysis on blood agar plates.
Identify the type of hemolysis: Streptococcus pneumoniae is known to be alpha-hemolytic. Alpha-hemolysis is characterized by partial hemolysis of red blood cells.
Recognize the appearance of alpha-hemolysis: On a blood agar plate, alpha-hemolysis results in a greenish discoloration around the bacterial colonies due to the partial breakdown of hemoglobin.
Compare with other types of hemolysis: Beta-hemolysis results in a clear, colorless zone due to complete lysis of red blood cells, while gamma-hemolysis shows no change in the blood agar.
Conclude the characteristics of the zone of clearance: For Streptococcus pneumoniae, the zone of clearance will be small and greenish in color, indicating partial hemolysis typical of alpha-hemolytic bacteria.
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