You are preparing a medium for growing fastidious bacteria and must add several heat-labile solutions of growth factors. Which of the following is an appropriate strategy for preparing and sterilizing this medium?

a. Pasteurize the medium.
b. Use dry heat to sterilize the medium.
c. Use UV radiation to sterilize this medium.
d. Prepare and autoclave the medium before adding the growth factors.
e. Prepare the medium, add the growth factors, and autoclave.

d. Prepare and autoclave the medium before adding the growth factors

Explanation:

A media is a nutrient solution for the growth of cells in vitro. They are of different sorts of media and theses are some of the properties of a media;

• Should be nutritive (contains the required amount of nutrients).

• Support the growth of the bacteria.

• have pH that is between neutral to slightly alkaline 7.3-7.4 (suitable)

• Hold suitable temperature (Bacteria grow at 37°C)

• Hold suitable atmosphere . .

• Sterilized.

The question above brings us to understand the concept of sterilization and medium preparation.

Note: For 15-20 minutes media are usually sterilized by autoclaving plates at 121°C and 1.02 atmosphere (i.e. 15 p.s.i.). With the autoclave, all bacteria, fungi, viruses, and spores are destroyed. .

Media Preparation & Sterilization A medium is sterilized (living organisms removed) before usage lab.

*Sterilization methods include: • Autoclaving. •Dry-heat. •Filtration. •UV exposure • Ethylene oxide.

Some media can't be sterilized by autoclaving because they contain component nutrients such as eggs or carbohydrates which denature because of heat (heat liable).

At timed like one prepare and autoclave the medium before adding the growth factors this is however suitable when culturing a fastidious bacteria for example.

A Culture may be seen as part of a specimen grown in culture media.

a) carbon, hydrogen

b) carbon, hydrogen, oxygen, nitrogen

c) carbon, hydrogen, oxygen, nitrogen, phosphorus

d) sugar

e) amino acid

f) nucleotide