2. culture medium:-
The food material or substance required for
growing microorganism in vitro(outside the body)
is called culture medium.
3. History of culture media :-
Louis Pasteur used simple broth made up of urine
or meat extracts
Robert Koch realized the importance of solid
media and used potato pieces to grow bacteria
On suggestion of Fannie Eilshemius agar was
used to solidify culture media
4. Disadvantage of gelatin:-
It existed as liquid as normal temperature(35-37’c
incubating temperature)
Digested by certain bacteria.
Before the use of agar attempts were made to
use gelatin as a solidifying agent.
Used for preparing solid medium.
1) Extract obtain from seaweed.
2) 2% agar is employed in solid medium.
3) Bacteriologically inert i.e no affected on the growth of
bacteria .
4) Remain solid at 37*C.
5) Melts at 98*C.
6) It is transparent.
agar
5. Requiredments of culture media:-
Nutrients:-
Energy source
Carbon source
Nitrogen source
Minerals salts- sulphate, phosphates, chlorides and carbonates of K,Mg,
and Ca
• A suitable pH= 7.2-7.4
Classification of culture media:-
Based on the consistency
a) Solid medium
b) Liquid medium
c) Semi solid medium
6. a) Solid media.
AGAR IS MOST COMMONLY USED AS A
SOLIDIFYING AGENT.
USED FOR SEPARATING MIXED BACTERIA.
BACTERIA CAN BE INDENTIFIED BASING ON
COLONY CHARACTER.
USED FOR THE ISOLATION OF BACTERIA AS PURE
CULTURE
EG- NUTRIENT AGAR, BLOOD AGAR
7. B) Liquid media.
ARE SOMETIMES REFERRED AS “BROTH”.
CONTAINS NO AGAR.
AVAILABLE FOR USE IN TEST-TUBES,
BOTTLES OR FLASKS.
BACTERIA GROWTH UNIFORMLY
PRODUCING GENERAL TURBIDITY EG.-
NUTRIENT BROTH.
Liquid media
8. c) Semi-solid media:-
Contain 0.5% agar.
Fairly soft and useful in demonstrating bacterial
mortilaty and seprating motile from non- motile
strain.
Eg- SIM
10. NATURAL MEDIa:-
THESE ARE WIDELY USED IN EARLY DAYS OF MICROBIOLOGY.
THSES INCLUDE MILK,URINE,DILUTED BLOOD,VEGETABLE
JUICE, MEAT EXTRACTS AND INFUSION ETC. NATURAL MEDIA
OR EMPIRICAL MEDIA CONTAIN EITHER ONLY OR A MAJOR
INGREDIENTS,PEPTONE(A HYDROLYSED PROTEIN).
PEPTONE SOURCES ARE ANIMAL(MEAT) AND
VEGETABLES(SOYABEANS,COTTON,SEEDS).PEPTONES ARE
MIXTURE CONTAINING VARIETY OF PEPTIDES, POLYPEPTIDES,
PROTEOSES, AMINO-ACIDS, CARBOHYDRATES
ETC.INCLUDING INORGANIC AND ORGANIC MICRO-NURITIONS.
11. Natural media:-
= AMONG MEAT EXTRACT AND INFUSION, BEEF
TEA(BEEF EXTRACT) AND AN AQUEOUS MEAT INFUSION
MADE BY INFUSING FRESH GROUND MEAT IN WATER
ARE COMMON INGREDIENTS OF MEDIA USEFUL FOR
MANY SPECIES.
BEEF INFUSIONS ARE RICH IN MINERALS,ORGANIC
MICRONUTRIENTS. PROTEIN, PROTEIN DERIVATES AND
CARBOHYDRATES.
CULTURE FLUIDS MADE FROM BEEF INFUSIONS ARE
COMMONLY CALLED INSFUSION BROTH,WHEREAS
THOSE MADE FROM BEEF EXTRACT AS EXTRACT
BROTH.
12. Natural media:-
FRESH EXTRACT OF VEGETABLES AS TAMATO,
ORANGES ETC. ARE USED FOR MANY BACTERIA, YEAST
AND MOLDS.
TO ANY NATURAL MEDIA, ONE MAY ADD MANY
DIFFERENT SUBSTANCES FOR DIFFERENT PURPOSE(AS
A CHOICE FOR A SPECIFIC BACTERIUM). THESE THAN
BECOME SPECIAL MEDIA .
FOR EXAMPLE BLOOD WHICH CONTAIN GREAT VARIETY
OF CARBOHYDRATE,ESTER,ALCOHOL,GLUCOSIDES
ETC. IS ADDED TO AN INFUSION BROTH, WHICH THEN IS
NAME AS BLOOD-INFUSION BROTH.
LACTOSE MAY BE ADDED TO BROTH AND KNOWN AS
LACTOSE BROTH.
14. Artificial media:-
THE MEDIA THAT ARE PREPARE ARTIFICIALLY THAT ARE
USED IN MICROBIOLOGICALLY LABORATORIES TO
CULTURE THE BACTERIA ARE REFFERED TO
ARTIFICIAL MEDIA.
ARTIFICIAL MEDIA OF EXACTLY KNOWN, REPRODUCIBLE
COMPOSITION ARE CALLED SYNTHETIC OR CHEMICALLY
DEFINED MEDIA.
THEY ARE PREPARED BY ADDING SEVERAL ORGANIC
AND IN ORGANIC NUTRIENTS.
15. Artificial media:-
IN MORDEN LABORATORY,DEHYDRATED MEDIA ARE USED.
THESE ARE PREPARED SIMPLY BY ADDING WEIGHED
PORTIONS OF THE INGREDIENTS TO THE REQUIRED
AMOUNT OF WATER.
THE SYNTHETIS MEDIUM MAY BE GENERAL PURPOSE
MEDIUM USED FOR MAJORITY OF MICROBES OR SELECTIVE
MEDIA USED FOR SELECTIVE MICROBES OR DIFFERENTIAL
MEDIA USED FOR DIFFERENTIAL ISOLATION OF MICROBES
IN SAME SAMPLE. WHICH WE STUDY IN PURE CULTURE
METHODS.
FOR EG. =
17. Living culture media:-
These are the group of the living cells as
tissue, or callus or an organ used for the
growing viruses.
Chick embroy is commonly used for
cultivation of viruses.
Yeast,molds and bacteria, if enter as
contaminants, they are able to multiply in the
fluid of the chick embryos as a culture tube.
18. Importance of culturing:-
1) TO IDENTIFIED AND CLINICAL DIAGNOSIS.
2) CULTURING ON SOLID MEDIA IS ANOTHER
CONVENIENT WAY OF SEPRATING BACTERIA
IN MIXTURE
3) CERTAIN GENETIC STUDIES AND
MANIPULATION OF THE CELLS ALSO NEED
THAT BACTERIA BE CULTURE INVITRO.
