Selective and Differential Media

Differential Media allows all types of microorganisms to grow, but some types look different, producing a new color.

Differential Media allows ________ (all or most) types of microorganisms to ________ (die or grow), but ________ (all or some) types look different, producing a new color.

EMB stands for Eosin Methylene Blue.

EMB stands for __________ __________ ___________.

Contains Lactose, which allows for the differentiation of Gram Negative (-) microorganisms based on their ability to ferment lactose

How is EMB differential?

Contains Eosin and Methylene Blue, which inhibits the growth of Gram Positive (+) microorganisms, therefore selective for Gram Negative (-) microorganisms

How is EMB selective?

Contains Mannitol and pH indicator, Phenol Red, which allow for the distinction between Gram Positive (+) microorganisms that can ferment Mannitol, and those that cannot

How is MSA differential?

Contains Salt, which inhibits the growth of Gram Negative (-) microorganisms, therefore selective for Gram Positive (+) microorganisms

How is MSA selective?

Contains Lactose, which allows for the differentiation of Gram Negative (-) microorganisms based on their ability to ferment Lactose

How is Mac differential?

Contains Bile Salt and Crystal Violet Dye, which inhibits the growth of Gram Positive (+) microorganisms, therefore selective for Gram Negative (-) microorganisms

How is Mac selective?

MSA stands for Mannitol Salt Agar.

MSA stands for __________ __________ __________.

Mac stands for MacConkey.

Mac stands for ______________.

False - Organisms that are able to ferment Mannitol will produce Acid, which decrease the pH of the sample, causing the Phenol Red pH indicator to turn Yellow.

T or F: Organisms that are able to ferment Mannitol will produce Acid, which increase the pH of the sample, causing the Phenol Red pH indicator to turn Red.

A Selective Medium is a culture medium designed to allow the growth of some kinds of organisms, but not others.

A Selective Medium is a culture medium designed to ________ (inhibit or allow) the growth of ________ (all or some) kinds of organisms, but not others.

An Enrichment Medium is designed to support the growth of a particular organism, hoping to increase the number of rare organisms.

An Enrichment Medium is designed to ___________ (weaken or support) the __________ (death or growth) of a particular organism, hoping to __________ (increase or decrease) the number of rare organisms.

C. Same color as plate (Purple)

What is the color of a non-fermented EMB plate (choose which letter corresponds to this test result)?

Same color as plate (Red)

What is the color of a non-fermented MSA plate?

C. Same color as plate (Raspberry)

What is the color of a non-fermented Mac plate (choose which letter corresponds to this test result)?

A. Metallic Green and Shiny

What is the color of a strongly fermented EMB plate (choose which letter corresponds to this test result)?

Yellow

What is the color of a strongly fermented MSA plate?

B. Pink with Precipitation

What is the color of a strongly fermented Mac plate (choose which letter corresponds to this test result)?

B. Some Pink

What is the color of a weakly fermented EMB plate (choose which letter corresponds to this test result)?

A. Some Pink

What is the color of a weakly fermented Mac plate (choose which letter corresponds to this test result)?

Allows all types of microorganisms to grow, but some types look different, producing a new color

What is the definition of a Differential Media?

Designed to allow the growth of some kinds of organisms, but not others

What is the definition of a Selective Media?

Designed to support the growth of a particular microorganism, hoping to increase the number of rare organisms

What is the definition of an Enrichment Medium? (Know the basics!)

1) Staphylococcus aureus (genus and species) 2) Staphylococcus epidermidis (genus and species)

Which organisms (genus and species) used in this exercise are Gram Positive (+)? 1) 2)

1) Escherichia coli (genus and species) 2) Enterobacter aerogenes (genus and species) 3) Proteus vulgaris (genus and species)

Which organisms (genus and species), used in this exercise, are Gram Negative (-)? 1) 2) 3)

TSA plate

Which plate used in lab this semester is neither Selective nor Differential?

1) Mannitol Salt Agar (MSA) 2) Eosin Methylene Blue (EMB) Agar 3) MacConkey (Mac) Agar

Which were the three plates used in this exercise? 1) 2) 3)