Mannitol Salt Agar is selective for staphylococci as the high salt (sodium chloride) levels prohibit most other bacteria from surviving and it is differential as Staphylococci ferment mannitol, producing acid, lowering the pH and turning the media yellow. The development of yellow media presumes the bacteria to be pathogenic Staphylococcus (usually S. aureus). From A Photographic Atlas for the Microbiology Laboratory by Leboffe and Pierce.
it only allows fungi to grow on the medium, and nothing else. so it selects for fungi.
The use of a medium that is both selective and differential can be justified in a few ways. They allowe the growth of organisms that can be of interest. The media can also be quite useful diagnostically in medical settings.
Because it is a selective medium
B. subtilis does not ferment glucose nor lactose
potato dextrose agar medium is used for fungal growth
Streptococcus cannot grow on MSA plates because MSA is a selective and differential media. It is selective because only certain microorganisms can grow on it due to its high NaCl content, in which this concentration - near 10% in MSA - has an inhibitory effect on most bacteria, such as Streptococci.
Mannitol salt agar or MSA is a commonly used growth medium in microbiology. It contains a high concentration (~7.5%-10%) of salt (NaCl), making it selective for Staphylococci (and Micrococcaceae) since this level of NaCl is inhibitory to most other bacteria.
An Acidic pH
Both
What is msa
As of July 2014, the market cap for MSA Safety Incorporporated (MSA) is $2,138,119,585.75.
selective medium
Peptone glucose agar (PGA) medium
The symbol for MSA Safety Incorporporated in the NYSE is: MSA.
mannitol is a type of sugar, so it supplies the carbon in the MSA medium
it only allows fungi to grow on the medium, and nothing else. so it selects for fungi.
The use of a medium that is both selective and differential can be justified in a few ways. They allowe the growth of organisms that can be of interest. The media can also be quite useful diagnostically in medical settings.