Download Culture Media & Culture Techniques

Culture Media
II MBBS
Dr Ekta Chourasia
Lecturer, Microbiology
Culture 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.
Oct 07
Dr Ekta, Microbiology, GMCA
Classification of Media
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Based on the consistency :
Solid media
Semisolid media
Liquid media
Oct 07
Dr Ekta, Microbiology, GMCA
Classification
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Based on the function or property:
- Simple media
- Enriched media
- Enrichment broth
- Selective media
- Indicator media
- Differential media
- Composite media
- Transport media
Oct 07
Dr Ekta, Microbiology, GMCA
Constituents Of Media
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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%)
Oct 07
Dr Ekta, Microbiology, GMCA
Simple Media
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Also called Basal medium
Most commonly used in routine labs.
e.g. Nutrient broth, NA
Oct 07
Dr Ekta, Microbiology, GMCA
Enriched Media
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Blood, serum or egg added to the
basal medium.
To grow bacteria which are more
exacting in nutritional requirements.
e.g. BA, CA
Oct 07
Dr Ekta, Microbiology, GMCA
Enrichment Broth (media)
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For mixed cultures or materials
containing more than one bacterium.
Contains substances which stimulates
wanted bacteria & inhibits unwanted
bacteria.
e.g. Tetrathionate broth
Oct 07
Dr Ekta, Microbiology, GMCA
Selective Media
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Substances added to a solid media to
favour the growth of wanted bacteria.
e.g. TCBS agar for Vibrio cholerae
Oct 07
Dr Ekta, Microbiology, GMCA
Indicator Media
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Change in the colour of indicator with
the growth of bacteria.
e.g. Sulphite in Wilson Blair media
for Salmonella typhi.
Oct 07
Dr Ekta, Microbiology, GMCA
Differential Media
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To bring out differing characteristics
of bacteria.
e.g. MacConkey’s agar
Oct 07
Dr Ekta, Microbiology, GMCA
Composite Media
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For identification of
isolates
e.g. Triple Sugar Iron
Transport Media
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For delicate organisms
Delay in transit
e.g. Stuart’s transport
media
Oct 07
Dr Ekta, Microbiology, GMCA