The document discusses different types of media used for growing bacteria. It describes media as being either solid or liquid, and routine laboratory media or synthetic media. Solid media uses agar as a solidifying agent and allows separation of mixed bacterial cultures by examining colony characteristics. Liquid media is used for profuse bacterial growth but does not allow separation of mixed cultures. Routine laboratory media includes basal, enriched, selective, indicator, transport, and storage media formulated for different growth and identification purposes. Synthetic media uses defined chemical compositions and is used for research.

1. B Y P R E E T H I R A T H I N A M
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2. MEDIA ARE OF DIFFERENT TYPES ON CONSISTENCY AND CHEMICAL
COMPOSITION.
Consistency
1. Solid
Media.
2. Liquid
Media.
Chemical
Composition
1. Routine
Laboratory
Media
2. Synthetic
Media.
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3. used for the isolation of bacteria as pure culture.
'Agar' is most commonly used to prepare solid media. Agar is
polysaccharide extract obtained from seaweed.
Agar is an ideal solidifying agent as it is
(a) Bacteriologically inert, i.e. no influence on bacterial growth,
(b) It remains solid at 37°C, and
(c) It is transparent.
It is used for profuse growth, e.g. blood culture in liquid media.
SOLID MEDIA
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4. ADVANTAGES OF SOLID MEDIA
Bacteria may be
identified by studying
the colony character
Mixed bacteria can be
separated.
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5. It is used for profuse growth.
e.g. blood culture in liquid media.
Mixed organisms cannot be
separated.
LIQUID MEDIA
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6. Chemical
Composition
Routine
Laboratory
Media
Synthetic Media
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7. These are classified into six types:
 Basal media,
Enriched media,
Selective media,
Indicator media,
Transport media, and
Storage media.
ROUTINE LABORATORY MEDIA
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8. Basal media are those that may be used for
growth (culture) of bacteria that do not need
enrichment of the media.
Examples: Nutrient broth, nutrient agar and
peptone water. Staphylococcus and
Enterobacteriaceae grow in these media
BASAL MEDIA
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9. The media are enriched usually by adding
blood, serum or egg.
Examples: Enriched media are blood agar
and Lowenstein-Jensen media. Streptococci
grow in blood agar media.
ENRICHED MEDIA.
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10.  These media favour the growth of a particular
bacterium by inhibiting the growth of undesired
bacteria and allowing growth of desirable bacteria.
 Examples: MacConkey agar, Lowenstein-Jensen
media, tellurite media (Tellurite inhibits the growth
of most of the throat organisms except diphtheria
bacilli).
 Antibiotic may be added to a medium for inhibition.
SELECTIVE MEDIA
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11. An indicator is included in the medium. A
particular organism causes change in the
indicator, e.g. blood, neutral red, tellurite.
Examples: Blood agar and MacConkey
agar are indicator media.
INDICATOR (DIFFERENTIAL)
MEDIA
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12. These media are used when specie-men
cannot be cultured soon after collection.
Examples: Cary-Blair medium, Amies
medium, Stuart medium.
TRANSPORT MEDIA
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13. Media used for storing the bacteria for a
long period of time.
Examples: Egg saline medium, chalk
cooked meat broth
STORAGE MEDIA
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14. These are chemically defined media
prepared from pure chemical
substances. It is used in research work.
SYNTHETIC MEDIA
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15. B Y P R E E T H I R A T H I N A M
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