Culture medium or growth medium is a liquid or gel designed to support the growth of microorganisms. There are different types of media suitable for growing different types of cells. Here, we will discuss microbiological cultures used for growing microbes, such as bacteria ,fungi, yeast & algae.

1. culture media
Dr. Rachana Choudhary
Asstt. Prof. Department of Microbiology
Shri Shankaracharya Mahavidyalaya Junwani , Bhilai

2. What is culturemedium
The food material or substances required for growing
microorganisms in vitro (outside the body) is called
Culture Medium.

3. Uses of culturemedium
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 of microorganisms.
3. to prepare biological products like vaccines, toxoides,
antigens…etc.

4. Composition of culturemedia
• Water
• Energy source
• Carbon source
• Nitrogen source
• Mineral salts
• Special growth
factors

5. I. Based on their consistency/Physical State
1. Solid medium
2. Liquid medium
3. Semi solid medium
II. Based on the constituents/ ingredients
1. Simple medium
2. Complex medium
3. Synthetic or defined medium
4. Special media
TYPESOF CULTUREMEDIA

6. Specialmedia
I. Enriched media
II. Enrichment media
III. Selective media
IV. Indicator media
V. Differential media
VI. Transport media
III .Based on Oxygenrequirement
a) Anaerobic media
b) Aerobic media

7. Classificationbasedon physicalstate
.
1.Solidmedium
agar is the most commonly used solidifying agent.
What is agar
• Golden –yellow granular powder
• Prepared from seaweeds.
• Not affected by the growth of the bacteria
• Melts at 98oC & sets at 42oC

8. 2.Liquidmedia
Are sometimes referred as “ broth “.bacteria grow
uniformly producing general turbidity.
eg. Nutrient broth

9. 3. Semi-solidmedia
Such media are soft and are useful in demonstrating
bacterial motility and separating motile from non-
motile strains .

10. Classificationbasedon theingredients
1. SIMPLEMEDIA
Nutrient Broth, Nutrient Agar
- Nutrient Broth consists of peptone, meat extract, NaCl,
- Nutrient Broth + 2% agar = Nutrient agar

11. 2 .Complexmedia
Such as blood agar, it has ingredients that exact components
are difficult to estimate.

12. 3.Syntheticor definedmedia
Specially prepared media from pure chemical substances
for research purpose and composition of every
component is well known
Example: peptone water –1% peptone + 0.5% NaCl in
water.

13. 4. Specialmedia
I. Enrichedmedia
• Substances like blood, serum, egg are added to
the simple medium.
• Used to grow bacteria that are exacting in their
nutritional needs.
Example: Blood agar, Chocolate agar

14. II. Enrichment media
• Liquid media used to isolate pathogens from a mixed culture.
• Media is incorporated with inhibitory substances to
suppress the unwanted organism.
E.g. Selenite F Broth for the isolation of Salmonella, Shigella
Alkaline Peptone Water forVibrio cholerae

15. III. Selectivemedia
The inhibitory substance is added to a solid media to inhibit
contaminating bacteria such as :Antibiotics,Dyes,Chemicals
Alteration of pH
Example. a. Eosin Methylene Blue Agar Medium
• Selective for gram negative bacteria
• The dye methylene blue in the medium inhibit the
growth of gram positive bacteria

16. b. Campylobacter agar
• Is used for isolation of Campylobacter jejuni from fecal or rectal
swab.
• Contain Bacteriological charcoal , Cefoperazone &
Amphotericin B.

17. c. Lowenstein –Jenson medium
• This solid medium used for
Mycobacterium tuberculosis.
• It 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.

18. IV. Differentialmedia
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.
Examples: MacConkey agar
CLED agar
TCBS agar
XLD agar

19. Examples of Differential media
MacConkey Agar medium
• Distinguish between lactose fermenters & non lactose fermenters.
• Lactose fermenters – Pink colonies
• Non lactose fermenters – colorless colonies

20. Cysteine Lactose Electrolyte Deficient Agar (CLED)
• For cultivation of pathogen from urine specimen , inhibit swarming
of proteus sp.

21. Thiosulfate-citrate-bile salts-sucrose agar TCBS)
Yellow coloured (sucrose fermenting) colonies of Vibrio cholerae

22. Xylose Lysine Deoxycholate Agar(XLD)
• Used for the recovery of Salmonella and Shigella species.

23. V.TRANSPORTMEDIA
• Media used for transporting the
samples.
• Delicate organisms may not survive
the time taken for transporting the
specimen without a transport media.
• Example:
– Stuart’s medium
– Buffered glycerol saline

24. III.BasedonOxygenrequirement
a. Anaerobicmedia
• These media are used to grow anaerobic organisms.
Example: Robertson’s cooked meat medium.
• Thioglycolate broth medium.
Robertson’s cooked meat
medium
Thioglycolate broth
medium

25. b. Aerobicmedia

26. CONCLUSION
The preparation of culture media and their underlying
culture technique goes hand in hand and affect each other
in either a good or bad way. When the preparation of a
culture media is already poor that is, it was not sterilized
properly or that the experimenter made some form of
mistake on the culture process, even though the culture
technique is good, the output or the growth of bacteria
would be influenced by the quality of media used.

27. References
• Textbook of Microbiology by R. Ananatnarayan & C.K.J
Paniker
• Textbook of Microbiology by R. P.Singh
• Textbook of Microbiology by P. Chakraborty
• Textbook of Microbiology Dubey & Maheshwari.
• Google Search

28. THANK YOU