Microbiology

1. CHANDIGARH UNIVERSITY
CELL BIOLOGY,MICROBIOLOGY,VIROLOGY
TOPIC-CULTURE MEDIA PREPARATION
22BNP-601
UID-22MBI20019
NAME-SHUBHAM K.
SUBMITTED TO- Dr.BALVIR KUMAR

2. CULTURE MEDIA PREPARATION

3. WHAT IS CULTURE MEDIA?
• 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 or yeast.

4. Nutrient media –
A source of amino acids and nitrogen (e.g., beef,
yeast extract). This is an undefined medium
because the amino acid source contains a variety
of compounds with the exact composition being
unknown. These media contain all the elements
that most bacteria need for growth and are non-
selective, so they are used for the general
cultivation and maintenance of bacteria kept in
laboratory-culture collections.

5. • Selective media – Used for the growth of only
selected microorganisms. For example, if a
microorganism is resistant to a certain
antibiotic, such as ampicillin or tetracycline,
then that antibiotic can be added to the
medium in order to prevent other cells, which
do not possess the resistance, from growing.

6. • Differential media – Also known as indicator
media, are used to distinguish one
microorganism type from another growing on
the same media. This type of media uses the
biochemical characteristics of a microorganism
growing in the presence of specific nutrients or
indicators (such as neutral red, phenol red,
eosin y, or methylene blue) added to the
medium to visibly indicate the defining
characteristics of a microorganism. This type of
media is used for the detection and
identification of microorganisms.

7. Key Points
• Culture media contains the nutrients needed
to sustain a microbe.
• Culture media can vary in many ingredients
allowing the media to select for or against
microbes.
• Glucose or glycerol are often used as carbon
sources, and ammonium salts or nitrates as
inorganic nitrogen sources in culture media.

8. TYPES OF CULTURE MEDIA
• The culture media are classified in many different
ways:
• Based on the physical state
– Liquid media
– Solid media
– Semisolid media
• Based on the presence or absence of oxygen
– Anaerobic media
– Aerobic media
• Based on nutritional factors
– Simple media
– Synthetic media
– Complex media
– Special media

9. • Microbial culture media preparation
• Microbial culture media preparation is the
process of mixing nutrients, agents for
buffering and maintaining the osmotic
balance, as well as selective inhibitors or
indicators to create an agar or broth that
supports the growth and the differentiation of
microorganisms.

10. INGREDIENTS
• Common ingredients of culture media:
Water: essential for bacterial growth, use deionized or distilled
water.
 Peptone: from hydrolised animal or plant protein, it provides
nitrogen and amino acid.
 Meat extract: provides amino acid, vitamins, mineral salts
(phosphate and sulphate).
 Yeast extract: used to stimulate the growth of bacteria.
 Mineral salts: traces of magnesium, potassium, iron and calcium
which are essential for bacterial enzyme activity.
 Carbohydrates: to provide bacteria with energy and carbon source.
Agar: inert polysaccharide from sea weed or marine algae, it is
solidifying agent with concentration of 1-2%, dissolves at 90-100 °C,
solidify at 45 °C.

12. • Preparation of culture media formulations, including liquid growth media
and culture media based on nutrient agar, is a common procedure in any
microbiology laboratory. The culture media formulation process involves
many steps and must be carried out with care to avoid cross
contamination and ultimately protect the health of consumers.
• Select culture media recipe from database
• Recalculate ingredient quantities according to the required culture media
volume
• Weigh main ingredients into the container
• Weigh trace ingredients on a high accuracy balance and add to the
container
• Pour in deionized water up to around 80% of the required volume
• Mix to dissolve the ingredients, gentle heating may be required
• Check the pH using a pH meter and adjust if necessary
• Top up the culture media to the required volume
• Label the container
• Sterilize in autoclave
• Document result.

13. Forms of media:
• Liquid form (broth): without agar (no solidifying
agent), used to grow bacteria in large quantity,
the growth appear as turbidity and if no growth it
appear clear.
• Solid form: by adding agar, it can be slant or deep
agar which is used to keep bacteria for long time
(up to 3 months), agar plate can be used to have
isolated colonies that help identification.
• Pure culture: culture containing only one type of
bacteria to study them. It is impossible to study
the bacteria when other organisms are present.

14. Types of media and their functions
• Basal media: allows growth of most non
pathogenic bacteria. E.g. nutrient agar.
• Enriched media: when the basal agar has
been enriched through adding blood or
serum. To allow the growth of pathogenic
bacteria. E.g. blood agar.
• Selective media: has certain inhibiting agent
to inhibit the growth of some bacteria and
allow growth of others.

15. THANKYOU