Selective media

Definition

Selective media are specialized types of growth media designed to favor the growth of specific microorganisms while inhibiting others. They are essential for isolating particular bacteria from mixed samples.

5 Must Know Facts For Your Next Test

1. Selective media contain specific agents that inhibit the growth of certain microbes while allowing others to thrive.
2. Common inhibitory substances in selective media include antibiotics, dyes, and salts.
3. MacConkey agar is a well-known example of selective media used to isolate Gram-negative bacteria.
4. Selective media are crucial for identifying pathogens in clinical samples by suppressing competing normal flora.
5. The choice of selective agent depends on the physiological characteristics of the target microorganism.

Review Questions

• What is the primary purpose of selective media in microbiology?
• Name an example of selective media and its use case.
• How do inhibitory substances in selective media work to isolate specific microorganisms?

Related terms

Differential Media:

Growth media that distinguish between different groups of microorganisms based on their biological characteristics.

Enrichment Media: Media designed to increase the numbers of desired microorganisms to detectable levels without necessarily inhibiting others.

MacConkey Agar:

A type of selective and differential medium used to isolate Gram-negative enteric bacteria and differentiate them based on lactose fermentation.