The document discusses microbial culture methods and the importance of culture media for bacterial growth, including its composition and types. It outlines the requirements for effective culture media and details various types based on consistency, composition, and application. Key examples include solid, liquid, and semisolid media, as well as enriched and differential media used for culturing specific microorganisms.

1. MEDIAS FOR
BACTERIAL
GROWTH
Prepared by
Dr. Malkiet Kaur
MM College of Pharmacy,
MM(DU)
Mullana

2. INTRODUCTION
Microbial Culture: It is a method of cultivating microbial organisms by letting them
reproduce in predetermined culture media under controlled laboratory conditions.
Culture media: It is defined as a solid or liquid preparation used for the growth,
transport and storage of microorganisms.
An effective culture medium must contain all the nutrients required for the growth of
microorganism.
Growth of microorganism is possible only if suitable culture media is available.

3. REASONS FOR CULTURING
1. Bacteria have to be grown for them to be identified and subsequent clinical
diagnosis.
2. Culturing on solid media is another is another convenient way of separating bacteria
in mixture.
3. To obtain antigens.
4. Certain genetic studies and manipulations of the cells also need that bacteria be
cultured in vitro

4. COMPOSITION OF CULTURE MEDIA
1. An artificial culture medium must provide all the nutritional components that a
bacterium gets in its natural habitat. It should provide similar environmental and
nutritional conditions that exists in its natural habitat.
2. A culture medium must contain water, a source of carbon and energy, source of
nitrogen, trace elements and some growth factors.
3. The pH of medium must be set accordingly.

5. REQUIREMENTS OF A MICROBIAL CULTURE MEDIA
• Must be sterile
• Contain appropriate nutrients
• Must be incubated at appropriate temperature

6. TYPES OF MICROBIAL CULTURE MEDIA
Culture Media Based on Consistency:
1. Solid Media
2. Semisolid media
3. Liquid Media
Culture Media Based on Composition:
1. Synthetic (chemically defined) media: Known chemical composition
2. Non-synthetic/ Complex (chemically not defined) media: Unknown chemical composition

7. Culture Media Based on Application:
1. Basic Media: nutrient broth, nutrient agar
2. Anaerobic media
3. Enriched Media
4. Enrichment Media
5. Differential Media
6. Transport Media
7. Assay Media
8. Selective Media:
i. Thayer-Martin Media
ii. Manittol- Salt Agar Media
iii. Mac-Conkey’s Agar Media
iv. Wilson and blair Agar Media
v. Crystal violet Blood Agar Media
vi. Pseudosel Agar Media

8. Culture Media Based on Consistency:
1. Liquid Media or nutrient broth: It is sometimes referred as “broth” . It has Liquid
consistency and shows Fast growth of bacteria. The bacteria grow uniformly producing the
general turbidity.
It contains no agar.
It is available for use in test tubes, bottles, or flasks.
Mixed organisms cannot be separated.

9. 2. Solid Media or nutrient agar: • Nutrient material that contains a solidifying agent
(1.5-2% agar): plates, slants, deeps • The most common solidifier is agar, first used by
Robert Koch.
Agar: It is golden-yellow granular powder.
3. Semisolid Media: To study the motility; Agar: 0.5-0.7%

10. Culture Media Based on Composition:
Nutrient material whose exact chemical composition is known (Defined Media):
• For chemoheterotrophs, must contain organic source of carbon and energy (e.g.: glucose, starch, etc.).
• May also contain amino acids, vitamins, and other important building blocks required by microbe.
• Expensive and not widely used. E.g.: Peptone broth
Nutrient material whose exact chemical composition is unknown (Complex Media):
• Widely used for heterotrophic bacteria and fungi.
• Made of extracts from yeast, meat, plants, protein digests etc.
• Composition may vary slightly from batch to batch.
• Vitamins and organic growth factors provided by meat and yeast extracts. Example:Yeast extract broth

11. Culture Media Based on Application:
Basal Media:
These are simple media that support most non-fastidious bacteria.
E.g.: Nutrient broth: Peptone, yeast extract, NaCl
Nutrient agar: Nutrient broth and 2% agar.
Anaerobic Growth Media:
Contain ingredients that chemically combine with oxygen and remove it from the medium. Example:
Sodium thioglycolate
Plates must be grown in oxygen free containers (anaerobic chambers).

12. Enriched Media
 It is a media that have been supplemented with highly nutritious materials such as blood,
serum, egg yolk or yeast extract for the purpose of cultivating fastidious organisms.
Addition of extra nutrients to basal medium makes them enriched media.
E.g.: Chocolate agar, Blood agar
Blood Agar: It contains mammalian blood (usually sheep or horse), typically at a
concentration of 5-10%, used to isolate fastidious organisms and detect hemolysis.
Chocolate agar: It contains red blood cells that have been lysed by slowly heating to 80o
C
and it is used for growing fastidious bacteria, such as Haemophilus Influenzae.

13. Enrichment Media
Enrichment media are a form of extremely selective medium that only permits a specific
species of a microbe to grow in it. These mediums prevent undesirable, commensal, or
contaminating microbes from growing.
Enrichment media are typically liquid in their consistency.
e.g.: Selenite F broth, tetrathionate broth, alkaline peptone water

14. Differential Media
It is defined in such a way that different bacteria can be recognised 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.
e.g.: MacConkey agar