Quick Answer: How Is MSA Selective And Differential?

Can E coli grow on MSA?

(A) Staphylococcus aureus, (B) Staphylococcus epidermidis, and (C) Escherichia coli streaked on a mannitol salt agar plate.

The growth of E.

coli was inhibited by the high salt concentration..

Is chocolate agar selective or differential?

Yellowing of chocolate agar was associated with alpha-hemolytic species of Streptococcus. The study demonstrated that reactions occurring on chocolate agar are useful in identifying gram-positive cocci. Chocolate agar, a differential medium for gram-positive cocci.

What makes MacConkey Agar both selective and differential?

This medium is both selective and differential. The selective ingredients are the bile salts and the dye, crystal violet which inhibit the growth of Gram-positive bacteria. The differential ingredient is lactose.

What media does Staphylococcus aureus grow on?

aureus will grow on general culture media such as Blood Agar and chocolated Blood Agar and therefore can be isolated from direct plating of clinical specimens. More specialised media, such as Staph/Strep Selective Medium contain antimicrobials.

Does Streptococcus grow on MSA?

MSA contains a high concentration of salt (NaCl), and therefore, selects for the growth of microbes that can tolerate high salt concentrations. Staphylococcus species are halotolerant, whereas Streptococcus species and many other organisms are inhibited by high concentrations of NaCl.

Why is mannitol salt agar both selective and differential?

Mannitol salt agar or MSA is a commonly used selective and differential growth medium in microbiology. It encourages the growth of a group of certain bacteria while inhibiting the growth of others. … If an organism can ferment mannitol, an acidic byproduct is formed that causes the phenol red in the agar to turn yellow.

What does MSA plate test for?

Mannitol Salt Agar (MSA) is used to determine if the bacteria is halophilic (salt loving) and if the bacteria can ferment mannitol. If the bacteria is able to grow then it is a halophilic bacteria, due to it’s ability to grow in a high salt environment.

Is blood agar selective?

Blood Agar Is Not a Selective Medium Blood agar is an enriched medium that provides an extra rich nutrient environment for microbes. Therefore, BAP is not a selective growth medium, since it supports the growth of a wide range of organisms.

What ingredient makes MSA selective?

Mannitol salt agar is selective due to the presence of 7.5% sodium chloride (NaCl).

What does a red color symbolize in a MSA plate?

Bacteria growing on mannitol salt agar are positive for mannitol fermentation if the culture medium under their colonies is changed from its normal red color to yellow, indicating acidic growth products. Bacteria unable to use mannitol usually change the medium to a magenta color in the vicinity of growth.

What substance makes MSA differential Why?

The substance that makes MSA differential is mannitol, because it can be effectively fermented by Staphylococcus aureus, but not other Staphylococcus species.

Does Micrococcus luteus grow on MSA?

When grown on mannitol salt agar some species of Micrococcus (Micrococcus is a normal flora of human skin, mucosa, and oropharynx), such as M. luteus (yellow) can produce yellow colonies. … They can ferment mannitol and produce lactic acid, producing yellow colored colonies on MSA.

Can media be both selective differential?

Selective and differential media can be combined and play an important role in the identification of bacteria by biochemical methods. Another commonly used medium that is both selective and differential is eosin-methylene blue (EMB) agar.

Is TSA selective or differential?

TSA (Trypticase Soy Agar) and NA (Nutrient Agar) are General Purpose Media that are not selective or differential, their purpose is simply to grow many types of bacteria cheaply. Here we will use a general purpose media to compare the growth on the selective and differential media.

What bacteria can grow on MSA?

Staphylococcus aureus and Staphylococcus epidermidis on mannitol salt agar. Mannitol salt agar is a commonly used growth medium in microbiology. It encourages the growth of a group of certain bacteria while inhibiting the growth of others.

What bacteria does not grow on blood agar?

Blood agar is an enriched, bacterial growth medium. Fastidious organisms, such as streptococci, do not grow well on ordinary growth media. Blood agar is a type of growth medium (trypticase soy agar enriched with 5% sheep blood) that encourages the growth of bacteria, such as streptococci, that otherwise wouldn’t grow.

What can grow on MSA plate?

Mannitol Salt Agar (MSA) Staphylococcus species, which commonly inhabit human skin, can grow on this high salt concentration (left plate in picture below). This is in contrast to Streptococcus species, whose growth is selected against by this high salt agar (plate on the right in the picture below).

How is MSA a differential media?

The differential ingredient in MSA is the sugar mannitol. … Organisms capable of using mannitol as a food source will produce acidic byproducts of fermentation that will lower the pH of the media. The acidity of the media will cause the pH indicator, phenol red, to turn yellow.