Page 62 - MNU microbiology theoritical 2025

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

Complex media

- 1 Basal media E.g. nutrient broth/agar

- 2 Enriched media
Complex medium to which additional nutrients are added (blood or

serum) required by many pathogens
E.g. Blood agar

- 3 Selective media
• Most types of media will allow most bacteria to grow

• Some media contain a selective agent, allowing some bacteria to

grow, while inhibiting other bacteria.

Eg. Lowenstien-Jensen (L-J) media: egg based media, inhibits

growth of contaminants by malachite green. Selective for

Mycobacteria.

- 4 Differential media

• Differential media does not necessarily inhibit bacterial growth, but instead makes

the bacteria look different

• Differential media contains substances that allow certain groups

of bacteria to appear differently when growing on it

(differential agent).

Eg. Blood agar (BA) is a differential medium.

5- Selective and Differential

• Media has agents added to it that prohibit the growth of certain organisms,

therefore selecting for the organisms of interest.

General Microbiology & Immunology (PM 401) theoretical handbook Page 51