Culture Media & Culture Techniques

Question 1

Indications/ Need for culture

Answer 1

• Isolate bacteria in pure cultures.
• Demonstrate their properties.
• Obtain sufficient growth for preparation of antigens & for other tests.
• Typing bacterial isolates.
• Antibiotic sensitivity.
• Estimate viable counts.
• Maintain stock cultures.

Question 2

The original media used by Louis Pasteur

Answer 2

urine or meat broth

Question 3

Liquid medium

Answer 3

diffuse growth

Question 4

Solid medium

Answer 4

discrete colonies

Question 5

cooked cut potato as early solid medium

Answer 5

Robert Koch

Question 6

discovered agar

Answer 6

Walther Hesse

Question 7

Classification of Media

Based on the consistency :

Answer 7

Solid media
Semisolid media
Liquid media

Question 8

• contains 2% agar
• Colony morphology, pigmentation, hemolysis can be appreciated.

Answer 8

Solid media

Question 9

ex. of Solid media

Answer 9

Nutrient agar, Blood agar

Question 10

• no agar.

Answer 10

Liquid media

Question 11

0.5% agar

Answer 11

Semi solid medium

Question 12

Classification

Based on the function or property:

Answer 12

• Simple media
• Enriched media
• Enrichment broth
• Selective media
• Indicator media
• Differential media
• Composite media
• Transport media

Question 13

mixture of partially digested proteins

Answer 13

Peptone

Question 14

Melting point

Answer 14

98°C

Question 15

Solidifying point

Answer 15

42°C

Question 16

Simple Media also called

Answer 16

Basal medium

Question 17

Most commonly used in routine labs

Answer 17

Simple Media

Question 18

Blood, serum or egg added to the basal medium

Answer 18

Enriched Media

Question 19

used to grow bacteria which are more exacting in nutritional requirements

Answer 19

Enriched Media

Question 20

For mixed cultures or materials containing more than one bacterium

Answer 20

Enrichment Broth

Question 21

Contains substances which stimulates wanted bacteria & inhibits unwanted bacteria

Answer 21

Enrichment Broth

Question 22

Substances added to a solid media to favour the growth of wanted bacteria.

Answer 22

Selective Media

Question 23

for V. cholerae

Answer 23

Thiosulfate-citrate-bile salts-sucrose agar

Question 24

For fungal culture and some bacteria

Answer 24

PDA – potato dextrose agar

Question 25

Fungi and yeast and also filamentous bacteria

Answer 25

Sabouraud Dextrose Agar (SDA)

Question 26

Change in the colour of indicator with the growth of bacteria

Answer 26

Indicator Media

Question 27

To bring out differing characteristics of bacteria.

Answer 27

Differential Media

Question 28

a nutrient blend used to support microbial growth

Answer 28

Medium

Question 29

The principle of sterilization in an ____________ is that steam under pressure is used to produce a temperature of __________ which if held for 15 minutes all microorganisms including bacterial endospores will be destroyed.

Answer 29

autoclave; 121ºC

Question 30

Heat to redness in Bunsen burner flame

Answer 30

Wire loop

Question 31

Each plate requires _______________ of agar

Answer 31

15-20 mL

Question 32

Each tube requires _____________ of broth/agar

Answer 32

5-10 mL

Question 33

• For inoculum preparation, Blood culture, for the isolation of pathogens from a mixture.

Answer 33

Liquid media

Question 34

ex. of liquid media

Answer 34

Nutrient broth

Question 35

ex. of Semi solid medium

Answer 35

motility medium

Question 36

Constituents Of Media

Answer 36

• Agar or agar- agar
• Peptone - mixture of partially digested proteins
• Yeast or meat extract
• NaCl

Question 37

ex. of Enriched Media

Answer 37

Blood Agar, Chocolate Agar

Question 38

ex. of Enrichment Broth (media)

Answer 38

Tetrathionate broth