This document discusses different types of culture media used to grow bacteria. It describes media as being solid, semisolid, or liquid based on consistency. Media are also classified based on their function as simple, enriched, enrichment, selective, indicator, differential, composite, or transport. Common constituents of media include agar, peptone, yeast or meat extract, and NaCl. The document provides examples of different media and their purposes, such as nutrient broth as a simple medium, blood agar as an enriched medium, and MacConkey agar as a differential medium.

1. Culture MediaCulture Media
II MBBS
Dr Ekta Chourasia
Lecturer, Microbiology

2. Oct 07 Dr Ekta, Microbiology, GMCA
Culture MediaCulture Media
Indications/ Need for culture -
 Isolate bacteria in pure cultures.
 Demonstrate their properties.
 Obtain sufficient growth for preparation
of antigens & for other tests.
 Typing bacterial isolates.
 Antibiotic sensitivity.
 Estimate viable counts.
 Maintain stock cultures.

3. Oct 07 Dr Ekta, Microbiology, GMCA
Classification of MediaClassification of Media

Based on the consistency :
Solid media
Semisolid media
Liquid media

4. Oct 07 Dr Ekta, Microbiology, GMCA
ClassificationClassification

Based on the function or property:
- Simple media
- Enriched media
- Enrichment broth
- Selective media
- Indicator media
- Differential media
- Composite media
- Transport media

5. Oct 07 Dr Ekta, Microbiology, GMCA
Constituents Of MediaConstituents Of Media

Agar or agar- agar

Peptone - mixture of partially digested
proteins

Yeast or meat extract

NaCl

Melting point : 98°C

Solidifying point : 42°C

% of agar : Solid media (2%)

6. Oct 07 Dr Ekta, Microbiology, GMCA
Simple MediaSimple Media

Also called Basal medium

Most commonly used in routine labs.
e.g. Nutrient broth, NA

7. Oct 07 Dr Ekta, Microbiology, GMCA
Enriched MediaEnriched Media

Blood, serum or egg added to the
basal medium.

To grow bacteria which are more
exacting in nutritional requirements.
e.g. BA, CA

8. Oct 07 Dr Ekta, Microbiology, GMCA
Enrichment Broth (media)Enrichment Broth (media)

For mixed cultures or materials
containing more than one bacterium.

Contains substances which stimulates
wanted bacteria & inhibits unwanted
bacteria.
e.g. Tetrathionate broth

9. Oct 07 Dr Ekta, Microbiology, GMCA
Selective MediaSelective Media

Substances added to a solid media to
favour the growth of wanted bacteria.
e.g. TCBS agar for Vibrio cholerae

10. Oct 07 Dr Ekta, Microbiology, GMCA
Indicator MediaIndicator Media

Change in the colour of indicator with
the growth of bacteria.
e.g. Sulphite in Wilson Blair media
for Salmonella typhi.

11. Oct 07 Dr Ekta, Microbiology, GMCA
Differential MediaDifferential Media

To bring out differing characteristics
of bacteria.
e.g. MacConkey’s agar

12. Oct 07 Dr Ekta, Microbiology, GMCA
Composite MediaComposite Media

For identification of
isolates
e.g. Triple Sugar Iron
Transport Media

For delicate organisms

Delay in transit
e.g. Stuart’s transport
media