Types of culture media Flashcards
What is culture medium?
- The food material or substances required for
growing microorganisms in vitro (outside the
body). - An artificial soil that contains nutritional and
environmental requirements.
Growth of an organism is known as
culture
Basic Requirements
of Culture Medium
- Water
- Energy source
- Carbon source
- Nitrogen source
- Salts
- pH
- Adequate oxidation
- Growth factors
Uses of culture medium
It is important to grow microorganisms outside the body
for the following purposes:
1.to identify the cause of infection from the clinical
sample, so that proper treatment can be given.
2.to study the characteristics or properties of
microorganisms.
3.to prepare biological products like vaccines, toxoides,
antigens…etc.
Types of culture media
I. Classification based on physical state
a) solid medium
b) semi solid medium
c) liquid medium
II. Classification based on the presence
and absence of oxygen
a) anaerobic media
b) aerobic media
III. Classification based on nutritional factors
a) simple medium
b) complex medium
c) synthetic or defined medium
d) Special media
agar is the most commonly used solidifying agent.
Solid medium
What is agar
- Golden –yellow granular powder
- Prepared from seaweeds.
- Not affected by the growth of the bacteria
- Melts at 98oC & sets at 42oC
lower agar concentration - 0.2 to
0.5%
Such media are soft and are useful in demonstrating
bacterial motility and separating motile from non-
motile strains.
Useful in the cultivation of microaerophilic bacteria
Semi-solid media
are sometimes referred as “ broth “.
bacteria grow uniformly producing general turbidity
eg. Nutrient broth
Peptone solution
Liquid media
- eg: Nutrient broth, N. agar
- NB consists of peptone, meat extract, NaCl,
- NB + 2% agar = Nutrient agar
Simple media (basal media)
such as blood agar, it has ingredients that exact
components are difficult to estimate.
Complex media
- specially prepared media from pure chemical
substances for research purpose and composition of
every component is well known - eg: peptone water –
1% peptone + 0.5% NaCl in water.
Synthetic or defined media
Special media
- Enriched media
- Selective media
- Differential media
- Transport media
- Anaerobic media
- Substances like blood, serum, egg are added to
the simple medium. - Used to grow bacteria that are exacting in their
nutritional needs.
Ex: fastidious microorganisms - Neisseria
gonorrhoeae) - eg: Blood agar, Chocolate agar
Enriched media
BAP contains mammalian blood(usually
sheep or horse) typically at a
concentration of 5-10%, used to isolate
fastidious organisms and detect
hemolysis.
Blood agar
contain red blood cells that have been lysed by
slowly heating to 80 c .and it used for growing
fastidious bacteria, such as Haemophilus
influenzae
Chocolate agar
Shows incomplete lysis of red blood cells
Alpha Hemolysis
shows complete lysis of red blood cells resulting in complete clearing around the colonies
Beta Hemolysis
no hemolysis, resulting in no change in the medium
Gamma Hemolysis
- The inhibitory substance is added to a solid media to inhibit
commensal or contaminating bacteria such as : - Antibiotics
- Dyes
- Chemicals
- Alteration of pH
Selective media
selective for Neisseria gonorrhoeae
* It usually contains the following combination of
antibiotics:
* Vancomycin:
which is able to kill most Gram-positive organisms.
* Colistin:
which is added to kill most Gram-negative organisms except
Neisseria.
* Nystatin:
which can kill most fungi
* Trimethoprim:
which inhibits Gram-negative organisms, especially
swarming Proteus.
Thayer Martin medium
kill most Gram-positive organism
Vancomycin
Kill most Gram-negative organisms except Neisseria
Colistin
Kill most Fungi
Nystatin
Which inhibits Gram-negative organism, especially swarming Proteus
Trimethoprim
- Selective for gram negative bacteria
- The dye methylene blue in the medium inhibit the growth of
gram positive bacteria.
Eosin methylene blue
- Is used for isolation of Campylobacter jejuni from fecal or
rectal swab. - Contain Bacteriological charcoal , Cefoperazone and
Amphotericin B.
Campylobacter agar
Lowenstein –Jenson medium
- is solid medium used for
Mycobacterium tuberculosis. - contain penicillin, nalidixic acid and
malachite green to inhibit growth of
gram positive and gram negative
bacteria, in order to limit growth to
Mycobacteria species only.
- are designed in such a way that different bacteria can be
recognized on the basis of their colony color. - Dyes and metabolic substrates are incorporated so that those
bacteria that utilize them appear as differently colored colonies.
Differential media
- MacConkey agar
- CLED agar
- TCBS agar
- XLD agar
Differential media
- Distinguish between lactose fermenters & non lactose
fermenters.
MacConkey medium
Lactose fermenters
Pink colonies
Non lactose fermenters
colorless colonies
Mannitol fermenters includes: Staphylococcus aureus
Mannitol Salt Agar
Non-mannitol fermenters includes
Staphylococcus epidermis
Positive growth but non-mannitol fermenters
Micrococcus luteus
Negative growth includes:
Escherichia coli
Pseudomonas aeruginosa
- Used for the isolation of Salmonella and Shigella
spp from clinical specimens and food samples.
Xylose Lysine Deoxycholate Agar(XLD)
In XLD AGAR Escherichia coli what color?
Yellow colonies
In XLD Agar Salmonella sp. is what color
Black colonies
- For cultivation of pathogen from urine specimen , inhibit
swarming of proteus sp.
Serratia and e-coli- cultivated
Cysteine Lactose Electrolyte Deficient
Agar(CLED)
- highly selective for the isolation of V. cholerae and V.
parahaemolyticus
Thiosulfate-citrate-bile salts-sucrose
agar(TCBS)
- Media used for transporting the
samples. - Delicate organisms may not
survive the time taken for
transporting the specimen without
a ____________. - Eg:
– Stuart’s medium
– Buffered glycerol saline
Transport media
- These media are used to grow anaerobic organisms.
Eg: - Robertson’s cooked meat medium.
- Thioglycolate broth medium.
Anaerobic media
TOOLS, GLASSWARE AND INSTRUMENTS
-CONICAL FLASK
-PETRI DISH
-COTTON
-ELECTRONIC BALANCE
-GRADUATED CYLINDER
-ALCOHOL LAMP
-BUNSEN BURNER
-HOTPLATE
-AUTOCLAVE
Assemble all of your chemicals in your
work area before you begin.
NEXT
Autoclave (sterilized)
all the glass wares
needed.
● Hugh and Leifson’s oxidation
fermentation medium
● Stuart’s and Amies media
● Mannitol motility media
Semi-solid media
Nutrient broth
Peptone solution
Liquid media
- Robertson’s cooked meat medium.
- Thioglycolate broth medium.
Anaerobic media
All organisms
Energy source
energy source
chemical
light
Chemical
chemotrophs
chemotrophs
Carbon source
organic compound or CO2
Organic compound
Chemoheterotrophs
Co2
chemoautotrophs
Chemoheterotrophs
final electron receptor
02- all animals most fungi protozoa, bacteria
not 02
-organic compounds
Fermentative streptococcus
-inorganic compounds
Electron transport chain Clostridium
Light
Phototrophs
Phototrophs
carbon source
-Organic compounds
Photoheterotrophs
-Photoautotrops
Uses H2O to reduce C02
Photoheterotrophs
green non sulfur bacteria
purple nonsulfur bacteria
Uses H2O to reduce C02
Oxygenic photosynthesis (plants, algae, eyanobacteria)
no uses H2O to reduce C02
Anoxygenic photosynthetic bacteria
green and purple bacteria
Isolation and cultivation of fungi
Sabouraud Dextrose Agar (SDA)
Plant tissue culture
Murashige and skoog
also called Ms media, MSO or MS
