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Culture media in microbiobiolgy
1.
2.
3. Subjects included;
• Cultivation
• Medium
• Inoculation of media
• The Requirements for Growth
• Preparation
• Classification
• Eplanation of types of media
functionally.
4. Cultivation;
The propagation of living organisms, applied
especially to the growth of microorganisms or other
cells in artificial media.
Medium
Any preparation that contains nutrients essential
for microorganisms growth.
Culture medium:
A nutrient substance that is used to grow
micro-organisms .
5. Inoculation of media
Introduction of infected material to the medium ,for
cultivation of organisms.
Agar
Is Complex polysaccharide, Used as solidifying
agent for culture media in Petri plates, slants, and
deeps. Generally not metabolized by microbes
Liquefies at 100°C
Solidifies at ~40°C
6. The Requirements for Growth
1.CHEMICAL REQUIREMENTS
(NUTRITIONAL FACTORS)
• Carbon
• Nitrogen, sulfur, and phosphorous
• Trace elements
• Organic growth factor
• Vitamins (e.g. folic acid, vitamin B-12, vitamin K)
• Oxygen
8. Preparation
• Wash hands & wear gloves
• Sterilize all equipments
• Pour D/W in glassware (required amount)
• Add powder ingredients (required amount)
• Heat to dissolve completely
• Autoclave
• Dispense the medium into tubes ,bottles
&plates
• Store at required temperature
• Sterilizing Culture Media
10. 1.Consistency
a ) Solid e.g nutrient agar
b ) Semi-solid e.g peptone water.
c ) Liquid medium e.g nutrient broth.
11. 2.Nutritional
a ) Simple e.g peptone water
b ) Complex e.g blood agar
c ) Synthetic e.g Davis /mingioli medium
12. 3.Functional
a) Basic media
b) Selective media
c ) Differential media
d ) Enriched media
e ) Enrichment media
f ) Transport media
13.
14. Basic media
• This is an undefined medium because
the amino acid source contains a
variety of compounds with the exact
composition being unknown.
• Nutrient media contain all the
elements that most bacteria need for
growth and are non-selective, so they
are used for the general cultivation and
maintenance of bacteria kept in
laboratory culture collections.
15. Basic media
• This media contains;
1.A carbon source such as glucose for
bacterial growth
2.Water
3.Various salts needed for bacterial growth
16. There are two types:
1. nutrient broth which is liquid media
18. Selective media
• culture medium that allows the growth
of certain types of organisms, while
inhibiting the growth of other
organisms
• Any agar media can be made
selective by addition of certain
inhibitory agents that
don’t affect the pathogen.
• Various approaches to make a
medium selective include addition
ofantibiotics, dyes, chemicals,
alteration of pH or a combination of
these medium
19. Selective media
• Thiosulphate citrate bile salt sucrose
(TCBS) which is selective for Vibrio
cholerae
• MacConkey agar contain bile salt
which is selective for
Enterobacteriaceae
20. Differential media
• distinguishs one microorganism type from
another based on a difference in colony
appearance includes (color, shape, or
growth pattern) on the media.
• uses the biochemical characteristics of a
microorganism growing in the presence of
specific nutrients or indicators (such as
neutral red, phenol red , or methylene blue)
added to the medium to visibly indicate the
defining characteristics of a microorganism
21. Differential media
• is used for the detection of microorganisms
and by molecular biologists to detect
recombinant strains of bacteria
• Examples;
Mannitol salt agar
Eosin methylene blue
MacConkey agar
22. • Mannitol salt agar
which is differential for mannitol
fermentation
Like Staphylococcus aureus change
the color of agar from pink to yellow
• Eosin methylene blue
which is differential for lactose
and sucrose fermentation
23. • MacConkey agar
which is differential for lactose fermentation Ex: E.coli
From non lactose fermentersEx: salmonella,shigella
24. Enriched media
• Enriched with
Blood,serum,extrapeptones,egg&
vitamins
• Used for:
cultivation of all fastidious organisms,
(haemophilus influenza&Streptococcus
spp.)
• Examples:
• Blood agar &chocolate agar
25. 7.Mixing
4.Adding the
the blood
contentstobottle
1.agar powders
with
molten
medium 2.Weighing out
at 45 c the ingredients
5.Autoclaving
8.Pouring
plates
3.Measuring
the desired
6.Adding
volume of
blood to the
water for
Preparation of blood agar out
9.Laying
medium
bloodmedia base
plates to set
medium
26. Chocolate agar
fastidious respiratory bacteria, such as Haemophilus
• Originally, red growth factors, like NADto a melted
influenzae need blood cells were added and hemin,
which are insideand heatedcells; thus, a prerequisite to
nutrient base red blood to approximately 75°C
growth is lysis the red blood cells
which lysed of the red blood cells. The agar is
named for the color and contains no actual chocolate.
27. Enrichment media
• A liquid culture medium promotes the
growth of a particular organism and
prevent the growth of normal
competitors.
• Prevent non pathogenic bacteria from
overgrowing the pathogenic bacteria
• Example: selenite-Fbroth
alkaline-peptone water
28. SELENITE –F BROTH
• Intended Use :is used for the selective
enrichment of Salmonella spp.
• Prepared Appearance: Prepared medium is
clear, with no to light precipitate and very pale
yellow.
29. ALKALINE PEPTONE WATER
• Intended use:
is used for the enrichment of Vibrio cholera
and Vibrio species from food, water, feces and
clinical studies.
• Prepared appearance:
The color is amber
30. Transport media
• Preserve viability and ratio of
microbes during its transportation
over 24_48 hours.
• Example:
CARY-BLAIR MEDIUM
STUART TRANSPORT MEDIUM
31. CARY-BLAIR MEDIUM
• Intended use;
• for the collection and transport of fecal and rectal
samples, maintaining viability of Salmonella and
Shigella.
• Survival depends upon:
1. bacterial type &concentration , transport medium
formulation, transport temperature and duration.
• the color is white opalescent
32. STUART TRANSPORT MEDIUM
• Intended use:
is a semisolid medium used in the transport and
preservation of specimens for the cultivation of
diverse organisms such as gonococci,
streptococci, Enterobacteria
The color : is blue in surface.
