Ch.2 - tools of the lab

Five “I’s” of Microbio

1. Inoculation (bacteria → media)

2. Incubation (store media)

3. Isolation (take colony out of media for pure culture, usually done by streaking)

4. inspection

5. identification

Pure, Mixed, and Contaminated Culture. What’s the difference?

Pure = 1

Mixed: 2/+ but easily separated

Contaminated: CAN’T be separated

General Purpose Media:

has lots of different nutrients so many different organisms can be grown

ex: broth or tsa agar

Defined vs Complex media

do we know the exact composition or not?

ex: agar vs blood

Enriched Media

Complex additives added like blood, vitamins, serum

* adding enriched doesn’t automatically make media complex

Selective Media

has ingredients that present certain organisms but inhibit the growth of others

ex: Macconkey Agar

Differential Media

makes a certain bacteria have a different growth than the others (but not inhibiting others)

ex: Urea Slants

What are all the kinds of media (5)? Give examples?

Defined + Complex,

Selective: MacConkey Agar

Differential: Urea slants

General Purpose: TSA Agar

Light Microscopy

Passing light through an organism

Direct vs Indirect Stains

Direct stains the cell, Indirect stains the background

Differential Stains

An example is Gram staining:

• thick cell walls are stained purple

• thin cell walls stained pink

Structural Stains

An example is a capsule stain

stains the structure something different