MicrobeWorld App


Microbes After Hours


Click for more "Microbes After Hours" videos

Join MicrobeWorld

Subscribe via Email


Featured Image

Featured Video

Ebola Virus explained


ASM House 200X200

Mannitol Salt Agar (MSA)

Mannitol Salt Agar (MSA)
•Important Ingredients: Phenol red, mannitol (sugar), 7.5% NaCl
•Differential: between pathogenic S. aureus and S. epidermidis
•Selective: NaCl inhibits non-halophilic organisms. Organism that can grow are halophilic.
•Mannitol Fermentors: fermentation of acid causes a drop in pH of the media and the indicator (phenol red) turns yellow.
A). Staphlococcus aureus: large yellow halo around growth indicates fermentation of mannitol.
B). Staphlococcus epidermidis: Growth but not color change to the media indicating no fermentation of mannitol.
C). Staphlococcus saprophyticus: small yellow halo around growth indicates fermentation of mannitol. (10% of S. saprophyticus ferment mannitol)
D). E. coli: no growth. Inhibited by the 7.5% NaCl.

Comments (0)

Collections (1)


American Society for Microbiology
2012 1752 N Street, N.W. • Washington, DC 20036-2904 • (202) 737-3600
American Society For Microbiology © 2014   |   Privacy Policy   |   Terms of Use