Question
Nutrient agar heated at 80°C used for
| A. |
Spore germination
|
| B. |
To grow mesophilic bacteria
|
| C. |
To grow thermophilic bacteria
|
| D. |
For clostridium isolation
|
Show Answer
|
Correct Answer � A:D
Explanation
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|
Ans. is ‘a’ > ‘d’ i.e., Spore germination > For clostridium isolation
- Heating for 20 minutes at 80 degrees centigrade destroys vegetative cells and activates the spores for germination.
- This method can be used to cultivate anaerobic spore-forming organisms (e.g. clostridium)
About options a & c
- Microorganisms can be grouped into broad (but not very precise) categories, according to their temperature ranges for growth.
- Psychrophiles (cold-loving) can grow at 0°C, and some even as low as -10°C; their upper limit is often about 25°C.
- Mesophlles grow in the moderate temperature range, from about 20°C (or lower) to 45°C.
- Thermophiles are heat-loving, with an optimum growth temperature of 50° or more, a maximum of up to 70°C or more, and a minimum of about 20°C.
- Hyperthermophiles have an optimum above 75°C and thus can grow at the highest temperatures tolerated by any organism. An extreme example is the genus Pyrodictium, found on geothermally heated areas of the sea bed. It has a temperature minimum of 82°, an optimum of 105° and a growth maximum of 110°C.
