Bacteriological culture media and cultivation of bacteria

1. Bacteriological culture
media and cultivation of
bacteria
Department of Microbiology and Immunology
MUHAS

2. Outlines
• Introduction
• Bacteriological culture media
– Meaning
– Types
– Culture methods

3. Introduction
• Culture
– Is any growth of microorganisms, usually
produced deliberately and artificially in the
laboratory.
• Culture medium
– Is an aqueous solution of the various nutrients
required for growth by a microorganism.
• A colony
– is a clone of cells originating from a single
cell

4. Bacteriological culture media
• Bacteriological culture media - are the
culture media that support the growth /
survival of bacteria example MacConkey
agar, Peptone water and Cary-Blair media.
• Contain all nutrients and necessary
physical growth parameters necessary
for bacterial growth

5. Types of culture media
• Based on their consistency
– Solid media
– Semi solid media
– Liquid media
• Based on the constituents/ingredients
– Synthetic or chemically defined media
– Non synthetic/chemically undefined/complex media
• Based on the purpose/functional use
– Simple/basal/general purpose media
– Enriched media

6. Types of culture media….
– Enrichment media
– Selective media
– Indicator media
– Differential media
– Sugar media
– Transport media
– Media for biochemical reactions
• Based on Oxygen requirement
- Aerobic media
- Anaerobic media

7. Based on their consistency
Solid media - contain 2% agar
• Useful for checking colony morphology,
pigmentation, hemolysis. Examples are
Nutrient agar (NA), Blood agar (BA) and
MacConkey agar (MCA)
• Solidifying agents: agar, gelatin, serum,
and eggs

8. Based on their consistency…
Semi solid media - 0.5% agar or less
• Useful for the cultivation of microaerophilic
bacteria or determination of bacterial
Motillity. Example: Semisolid Rappaport
Vassiliadis Medium
Liquid/broth media - no agar
• For inoculum preparation, Blood culture, for the
isolation of pathogens from a mixture. Example
Nutrient broth

9. Based on their consistency…
Solid media
Liquid/ Broth media
Semi solid media

10. Based on the constituents/ ingredients
Synthetic or chemically defined medium
• Prepared from pure chemical substances and its
exact composition is known. Example: Peptone
water – 1% peptone + 0.5% NaCl in water
Non synthetic/chemically undefined/complex
medium
• They have added ingredients.
• Prepared using natural products such as yeast
extract or meat extracts or vegetable infusions.
Examples: Luria broth

11. Based on the
purpose/functional use
• Simple/basal/general
purpose medium
– Support the growth of a
wide range of bacteria.
– No inhibitory substance.
– Examples: Nutrient agar
and Nutrient broth
Nutrient agar
Nutrient broth

12. Based on the
purpose/functional use..
• Enriched media
– More nutrients have been
added in order to support the
growth of fastidious or
restrictive or exacting
pathogens such as
Haemophilus influenzae
– Example: Blood agar &
Chocolate agar Chocolate agar
Blood agar

13. Based on the purpose
/functional use..
• Enrichment media
– Liquid media which are selective
or inhibitory
– Increase the relative number of a
desired microorganism
Example:
– Alkaline peptone water - for Vibrio
cholerae
– Salenite F broth – for the isolation
of Salmonella and Shigella spp
Salenite F broth
Alkaline peptone water

14. Based on the purpose
/functional use..
• Selective media
– The inhibitory substance
is added to a solid media.
• Examples
– Mac Conkey’s medium
for gram negative
bacteria
– TCBS – for V. cholerae
– LJ medium – M.
tuberculosis TCBS medium
MacConkey agar
LJ medium

15. Based on the purpose
/functional use..
• Indicator media
– These media contain
an indicator which
changes its colour
when a bacterium
grows in them
– Example:
Christensen’s urease
media & CLED CLED
Christensen’s urease media

16. Based on the purpose
/functional use..
• Differential media
– A media which has substances
incorporated in it enabling it to
distinguish between bacteria.
– Example: Mac Conkey medium
– Lactose fermenters – Pink
colonies
– Non lactose fermenters –
Colourless colonies Inoculated MCA
Un-inoculated MCA

17. Based on the purpose
/functional use..
• Sugar media
– Media containing any fermentable
substance.
– Example: glucose, arabinose,
lactose, starch etc.
– Media consists of 1% of the sugar
in peptone water.
– Contain a small tube (Durham’s
tube) for the detection of gas by
the bacteria.

18. Based on the purpose
/functional use..
• Transport media
– Media used for transporting
the samples.
– Delicate organisms may not
survive the time taken for
transporting the specimen
without a transport media.
– Example: Stuart’s medium

19. Based on the purpose /functional use..
• Media for biochemical reactions
Kligler Iron Agar (KIA) - hydrogen sulfide
production, gas production and fermentation of
dextrose and lactose.
SIM – Sulphur and Indole production and Motility
Simmon’s Citrate medium –Citrate utilization
Christensen’s urease medium – Urease
production

20. Media for biochemical reactions
KIA Christensen’s
urease medium
Simmon’s Citrate
medium
SIM

21. Based on Oxygen
requirement
• Anaerobic media
– These media are used to
grow anaerobic
organisms.
– Example: Robertson’s
cooked meat medium
and Thioglycolate
medium.
Robertson’s cooked meat
medium
Thioglycolate medium

22. Culture method
• Streak culture
• Lawn culture
• Stroke culture
• Stab culture
• Pour plate culture

23. Streak culture
• Used for the isolation of bacteria in pure
culture from clinical specimens.
• Platinum wire or Nichrome wire is used.

24. Lawn culture
• Provides a uniform surface growth of the
bacterium.
• Lawn cultures are prepared by flooding the
surface of the plate with a liquid
suspension of the bacterium

25. Stroke culture
• Stroke culture is made in
tubes containing agar slope /
slant
Stab culture
• Prepared by puncturing a
suitable medium – gelatin or
glucose agar with a long,
straight, charged wire.

26. Pour plate culture
• Agar medium is melted (15 ml) and cooled
to 45oC
• 1 ml of the inoculum is added to the molten
agar.
• Mix well and pour to a sterile petri dish.
• Allow it to set
• Incubate at 37oCcolonies will be distributed
throughout the depth of the medium.

27. HAVE A NICE
PRACTICAL SESSION