Page 98 - MNUmicrobiology practical 2025

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

Learning outcomes

• Define the culture media
• Classify culture media based on consistency/ physical state

• Classify culture media based on chemical composition/application

• Types of culture media based on oxygen requirement
• Recognize the use of each media

What is culture media

The media is a source of nutrients to support the growth of the micro-organisms in-

vitro. The media helps in the growth and counting of microbial cells, selection of

microorganisms, and survival of microorganisms. The culture medium can be liquid or
gel.

Classification of culture media

A- Based on consistency

1- Solid medium

Solid medium contains agar (solidifying agent), at a concentration of (1.5-2.0) %.

Solid medium is useful for isolating bacteria or for determining the colony

characteristics of the isolate. E.g. Nutrient agar

2- Semi-solid media
Semisolid media are prepared with agar at concentrations of 0.5% or less. They have

soft custard like consistency and are useful for the cultivation of microaerophilic
bacteria or for determination of bacterial motility. E.g. SIM media

General Microbiology & Immunology (PM 401) Practical note Page 87