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preparation of culture media

preparation of culture media
we culturing microorganisms to see and sudy it .
in the culture media there is three type of media solid
sime solid and liquid .
How to make culture media :
1. Weigh 6.5 grams of the sterile nutrient
broth and transfer into the clean conical
2. Add 500 ml of distilled water into the
measuring cylinder and transfer into the
conical flask .
3. Put the conical flask with the media
solution from step 2 into an autoclave
4. Allow the autoclave to cool down.
5. Put the petri dishes into a hot air oven at
80ºC for one hour to sterilize them.
6. Remove the conical flask containing the
now sterile media from the autoclave.
7. Label the petri dishes and store in a
refrigerator for later use.
Make dilution for water sample .
we use dilution to reduce the amount of
bactiria in the water .
to make dilution for water sample first
prepare 5 test tube add 9ml dilution liquid
and add for first tube 2ml from bacteria
after that take with pipette 1ml and add it
to second tube repeat that to 5th tube.
Like that we reduce amount of bacteria .
Characteristics of Bactria colony
morphology .
characteristics used to accurately and
consistently describe the morphology of
bacterial colony.
We can describe bacterial colony in 6
classification : Size Shape Color Texture
Height and Edge.
Antibiotic .
Antibiotics they inhibits the growth and
replication of a bacteria and kill it .
Antibiotics sensitivity test:
1.Select a pure culture plate of one of the
organisms to be tested.
2.Aseptically emulsify a colony from the plate in
the sterile saline solution. Mix it thoroughly to
ensure that no solid material from the colony
is visible in the saline solution.
3.Repeat until the turbidity of the saline solution
visually match that of the standard turbidity.
4.Take a sterile swab and dip it into the broth
culture of organism.
5.Gently squeeze the swab against the inside of
the tube in order to remove excess fluid in the
6.Take a sterile Mueller-Hinton agar (MHA) plate
or a nutrient agar (NA) plate.
7.Use the swab with the test organism to streak
a MHA plate or a NA plate for a lawn of growth.
8.After the streaking is complete, allow the plate
to dry for 5 minutes.
9.Antibiotic discs can be placed on the surface
of the agar using sterilized forceps.
10. Gently press the discs onto the surface of
the agar using flame sterilized forceps or
inoculation loop.
11. Carefully invert the inoculated plates and
incubate for 24 hours at 37° C.
12. After that you can see the different in zone
Gram staining
Gram stain is a method of staining used to
distinguish and classify bacterial species
into two large groups grampositive and gram-negative.
We use gram staining to see bacteria in
the microscope .
First Preparing a smear for staining and
Flame your inoculating loop drop water on
clean slide spared it into the slide let the
smear dry after the heat it , flood the
smear with stain and let it 1 minuet after
that you can see it under microscope .