Topic 11: Special Media for Isolating Bacteria

Products of bacterial metabolism

________ can react with the dyes to produce a color change in the medium.

selective culturing

To help isolate organisms found in the minority, various enrichment and ________ methods are available that either enhance the growth of some organisms or inhibit the growth of other organisms.

Selective media

contain chemicals that prevent the growth of unwanted bacteria without inhibiting the growth of the desired organism

Enrichment media

contain chemicals that enhance the growth of desired bacteria

Differential media

contain various nutrients that allow the investigator to distinguish one bacterium from another by how they metabolize or change the media with a waste product

What is a major limitation of dilution techniques?

organisms present in limited amounts may be diluted out on plates filled with dominant bacteria

What is used to help isolate organisms found in the minority in dilution plates?

enrichment and selective culturing methods that enhance and inhibit growth

What is selective media?

prevent the growth of unwanted bacteria without inhibiting (or affecting) the growth of the desired organism

What is enrichment media?

enhance the growth of desired bacteria (doesn't affect grow of other bacteria)

True or False: Enrichment media is usually a solid media.

False - usually liquid media

What is differential media?

used to distinguish one bacterium from another by how they metabolize or change the media with a waste product

Why are dyes often used in differential media?

products of bacterial metabolism can react with the dyes to produce a color change in the medium