Page 99 - MNUmicrobiology practical 2025

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

3- Liquid (Broth) medium

No agar; medium serves various purposes such as propagation of large number of

organisms, and various other tests. e.g. MR-VP broth.

B- On the basis of purpose/ functional use/ application
1. General purpose media/ Basic media

These are simple media that are generally used for the primary isolation of
microorganisms. This media allows the growth; of non- fastidious bacteria without any

enrichment source E.g. Peptone water, Nutrient broth, Nutrient agar

Nutrient broth:
• Uses: It is a common media for cultivation of bacteria.

• Composition: boiled ground meat with water, filter to get
clear solution (meat extract), pepton, 0.5% NaCl, neutral PH,

sterilized.

• Shape: light yellow transparent fluid

Pepton water:
Composition: 1% pepton, 0.5% NaCl and water, the

components are dissolved by heat, filter, sterilized

Uses: - used in indol production test

- used as base of sugar media

Nutrient agar:
Composition

• It is composed of nutrient broth with (1.5-2%) agar.

• Solid at room temp, it liquefies by heating above 45 C

Uses: it is common media for cultivation and isolating bacteria

General Microbiology & Immunology (PM 401) Practical note Page 88