Mannitol Salt Agar

Micro lab 2

What types of media is this?

• Differential

• Selective

Definition of differential media

A media used to easily see the differences between different microorganisms

Selective media definition

Only allows 1 specific or 1 type of organism to grow and suppresses the growth of anything else

Components of mannitol salt agar

1. carbohydrate mannitol

2. 7.5% sodium chloride (NaCl)

3. pH indicator phenol red

phenol red pH readings

• Yellow; Below pH 6.8 (acidic)

• Red: 7.4-8.4 (neutral range)

• Pink: 8.4 and above ( closer to alkaline)

Ph chart as reference

What is this media selective for

This media is selective for members of the Staphylococcus species

How is this media supportive of the Staphylococcus microorganisms?

Staphylococcus grows in salt rich environments

The NaCl ( salt) on the agar is high enough to kill most other bacteria

What provides the fermentation aspect of this media?

mannitol allows for fermentation

How does mannitol make this media a differential media

If the staphylococcus is able to ferment the mannitol then it shows up yellow indicating that the species of staph is of the Staphylococcus Aureus species

If the staphylococcus does not ferment the mannitol, it stays red and indicates the staph is the staph is Staphylococcus Epidermis species

Main take away and applications of Mannitol Salt Agar Application

• Isolation and differentiation of Staphylococcus Aureus from other Staphylococcus species

Misc Staphylococcus info

• Staphylococcus is Gram +

• Is part of the normal skin microbiota because we have salt on our skin and staphylococcus likes that

Example of manifold salt agar