Culture media Flashcards
Mixtures composed of nutrients intended for the growth and identification of microorganisms
Energy source, C- and N-source, Salts, Optimum pH, Growth factors
Isolation, differentiation, identification, characterization, studying of responses/behavior
CULTURE MEDIA
CLASSIFICATION OF CULTURE MEDIA
1.5% to 2.0% agar
Solid
CLASSIFICATION OF CULTURE MEDIA
0.5% to 1.0% agar
Semi-solid
CLASSIFICATION OF CULTURE MEDIA
no agar
Liquid
came from the Malay word “agar-agar” which is the local word for the red algae in which the gel is harvested from
Agar
CLASSIFICATION OF CULTURE MEDIA
By application/use
Differential media
Selective media
Enrichment media
Enriched media
Simple media
what kind of media is used for the cultivation of non-fastidious microorganisms
Simple media
Simple media example
Nutrient Agar
Nutrient Broth
Potato dextrose agar
contains additional nutrients for the growth of fastidious microorganisms
Enriched media
are those that require special/particular nutritional requirements
Fastidious mcgs
Enriched media examples
Sheep blood, calf brain infusion, heart infusion broth
contain nutrients that allow a particular group of organisms that might not be present in sufficient numbers in the specimen to be isolated and identified
Enrichment media
Enrichment media examples
Selenite F - enrichment S. enterica serotype Typhi from fecal samples Tetrathionate broth - for Salmonella from feces and sewage
inhibit the growth of certain bacteria while permitting the growth of others
Selective media
Examples of Selective media
Mannitol Salt Agar (MSA)
Brilliant Green Lactose Broth (BGLBB)
Potato Dextrose Agar acidified w 10% tartaric acid
media that can distinguish one group or species from another. They have components that make observable changes when a certain biochemical occurs
Differential media
Examples of Differential media
MacConkey Agar (MAC)
Eosin Methylene Blue Agar (EMBA)
Blood Agar Plate (BAP)
Culture media is typically prepared as:
broth tube
agar slant
butt
butt slant
agar plate
When preparing a batch of media consider the following:
Number of setups/treatments
Number of replicates
Number of controls
The media components
Type of set-ups e.g. plates, slants, etc.
Adjust the pH using diluted _______.
HCl or NaOH
For nutrient agar, it is recommended to adjust it to ______ (pH)
6.8
Tubes sterilization
Distribute to tubes, autoclave sterilize, then form to a butt, butt-slant or slant.
sterilization of Heat stable components
- Steam sterilization (water is added)
- 121 °C, 15 psi, 15 minutes to 20 minutes
- Autoclaves and pressure cookers
sterilization of Non-heat stable components
Filtration using 0.45 μm or 0.2 μm pore size filters such nitrocellulose and PTFE
Examples of Non-heat stable components
organic acids, vitamins, antibiotics
Included in the sterilization process to ensure that the sterilization is effective
Sterility Indicators
ink/chemical that changes color due to high temp
steam autoclave tape
tubes that contains heat resistant endospores , usually ____, which from purple turns to yellow
B. stearothermophilus
For components that were filter sterilized they should be added prior to dispensing and when the media is cool enough. What is the temperature?
(around 50 °C).
For blood agar plate, ______ of non-hemolyzed sheep or horse blood is added to cooled (50 °C) basal media.
5 to 10%
the media should be heated again after adding the blood. The heating lyses the blood cells
chocolate agar
