10 Questions
What color does the pH indicator turn when encountering acid on the mannitol salt agar plate?
Bright yellow
How does the appearance of the non-mannitol fermenter differ from the mannitol fermenter on the agar surface?
It shows no color change of the agar
What is the role of sodium chloride in mannitol salt agar?
Prevents the growth of unwanted Gram-negative organisms
Why is it important for mannitol salt agar to inhibit the growth of Gram-negative organisms?
They compete for resources with Staphylococcal species
In what way does the yellow halo on the agar indicate the spread of acid from mannitol fermentation?
The halo indicates how far acid has reached from fermentation
What is the purpose of Mannitol Salt Agar?
To select for and differentiate among Gram-positive Staphylococcus species
Why is a pH indicator added to Mannitol Salt Agar plates?
To differentiate organisms based on their metabolic capabilities
How does Mannitol Salt Agar differentiate among different organisms?
By their ability to produce acid during fermentation
What makes Mannitol Salt Agar a differential media?
The ability to differentiate among organisms based on their metabolic characteristics
Why is Mannitol important in Mannitol Salt Agar?
It is the ingredient that makes the media differential
Study Notes
Mannitol Salt Agar Plate
- When a Gram-positive organism capable of mannitol fermentation is inoculated on the plate, it turns the pink agar yellow due to acid production.
Characteristics of Mannitol Salt Agar
- Selective and differential medium
- Specifically selects for and promotes growth of Gram-positive Staphylococcus species
- Contains mannitol, a carbohydrate that some organisms can ferment while others cannot
- Contains a pH indicator that changes the agar color in response to acid production
Role of Sodium Chloride (Salt)
- Inhibits the growth of unwanted Gram-negative organisms
- Makes mannitol salt agar selective for Gram-positive Staphylococcus species
- Staphylococcal species can live in salty environments, such as on human skin
pH Indicator and Mannitol Fermentation
- When an organism ferments mannitol, it produces acid as a waste product
- The acid diffuses through the agar, decreasing the pH and turning the agar yellow
- The yellow halo surrounding the organism indicates the spread of acid from mannitol fermentation
Explore the reading and procedure of Mannitol Salt Agar, a selective and differential media used in medical microbiology labs. Learn about how this type of media assists in identifying unknown organisms by selecting for specific types and differentiating among different species.
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