Page 61 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

Cultivation of bacteria

Culture media
Nutrient material prepared for the growth of microorganisms

• Can be used to:
- Enrich the numbers of bacteria

- Select certain bacteria and suppress others.

- Differentiate between different kinds of bacteria

• Characters of media
1- It must contain basic nutrients (CHNOPS) and growth factors.

2- It has suitable moisture content, pH and salt concentration.

3- It must be sterile.

• The media may be:

Liquid medium solid medium

➢ Components are dissolved in water ➢ A medium to which has been added a

and sterilized. gelling agent
➢ The simple liquid medium is - Agar (most commonly used)
nutrient broth - Gelatin

Types of culture media
There are two basic types of media:

1- Complex media 2- Synthetic media

➢ Often consist of plant or animal ➢ Chemically defined media.
extracts, such as soybean meal, milk - Contain pure chemical compounds.

protein, etc. Include most routine - Ingredient must be of analytical quality.
laboratory media, - Water must be distilled.
e.g., tryptic soya broth e.g. Media used in bacterial genetics

experiments

General Microbiology & Immunology (PM 401) theoretical handbook Page 50