1. Name some simple media.
- Peptone water, Nutrient broth and agar.
2. Name some enriched media.
- Blood agar, Chocolate agar, Dorset egg medium and Loeffler’s
serum medium.
3. How are media made selective?
a) Antibiotic - Thayer - Martin agar
for Neisseria gonorrhoeae, CIN agar for Yersinia
enterocolitica
b) Dye - Brilliant green - in LJ media for
Mycobacterium tuberculosis, Crystal violet blood agar for Group A
Streptococcus,
c) pH - TCBS and alkaline peptone water (pH
>8) for Vibrio cholerae.
d) Salt -Mannitol salt agar, with 7.5% NaCl
for Staphylococcus aureus.
e) Chemicals - Bile salts in Mac Conkey’s
agar, Potassium tellurite in Hoyle’s medium and Mc Leod’s
medium for Corynebacterium diphtheriae, Sodium azide agar
for Enterococcus sp., Bismuth sulphite in Wilson and Blair
agar for Salmonella typhi.
f) Disinfectant - i) Cetrimide agar for
Pseudomonas aeruginosa
4. Name some transport media.
- Amies medium, Pikes medium, Stuart’s medium, Buffered glycerol
saline and VR medium.
5. Name some enrichment broth.
- Selenite F broth, Tetrathionate broth and Alkaline peptone
water.
6. How are the media sterilized?
- Most media are sterilized by autoclaving.
7. Which media are not autoclavable?
- Blood, serum, antibiotic and sugar containing media.
- Highly selective media such as Wilson & Blair’s, TCBS etc.
8. How are media solidified?
- By adding 2 - 3% agar.
9. What is the percentage of blood used in Blood agar?
- 5% defibrinated sheep blood.
10. What is the melting and solidifying point of agar?
- 95oC and 45oC respectively.
11. How is chocolate agar prepared?
- By adding 5% blood to hot, melted nutrient agar. It is also
known as lysed blood agar.
12. Name the serum containing media.
- Loeffler’s serum slope and Hiss serum water.
13. Name the egg containing media.
- Dorset egg medium and LJ medium.
14. Name the media, which enhances Staphylococcal pigment
production.
- Milk agar and glycerol monoacetate agar.
15. What is the melting point of gelatin?
- 24oC. It remains as liquid when incubated at 37oC.
16. Which medium is used to selectively grow gram positive
bacteria?
- Colistin-Nalidixic acid Agar (CNA).
17. Name some lactose fermenters and non-lactose fermenters.
-Lactose fermenters are Klebsiella pneumoniae and Escherichia
coli
-Non-lactose fermenters are Salmonella typhi, Proteus spp,
Shigella spp, Pseudomonas aeruginosa, Vibrio cholerae
18. Name the media used for cultivating anaerobes.
- Robertson’s Cooked Meat medium (R.C.M), chopped medat glucose
broth and Thioglycollate broth are the liquid media. Blood
agar with suitable blood agar base, reducing agents and nutrition
supplements can be used to grow anaerobes.
19. What are the media used for blood culture?
- Glucose broth, Bile broth and Brain heart infusion broth.
20. Why is agar preferred to gelatin?
- Agar is required in smaller quantity (2-3%, in contrast to
10-15% of gelatin), is solid at the incubating temperature (while
gelatin is liquid at this temperature) and does not contribute to
the nutritional property of the medium (gelatin is liquefied by
some bacteria).
21. What are indicator media?
- Indicator media indicates the presence of certain bacteria by
the change in colour. MacConkey's medium indicates the growth of
lactose fermenters by pink coloured colonies.
22. What are differential media?
- Media that aid in differentiation among bacteria based on some
phenotypic property (such as sugar fermentation) are differential
media. MacConkey differentiates LF from NLF.
23. What do you mean by enriched media?
- Media that are supplemented with extra nutrition in the form of
blood, serum, egg yolk etc are enriched media. They are suitable
for fastidious bacteria.
24. What is biphasic medium?
Biphasic medium contains both solid and liquid medium in the same
bottle. Blood is inoculated into the liquid medium and subcultures
are performed by tilting the bottle. Used in Castaneda method of
Blood culture.
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