Question

Anaerobic Cultivation -- Microbiology Lab

a. What are the steps of anaerobic cultivation?

b. Why are two different broths used (nutrient agar and thioglycolate medium)?

c. Nutrient agar is great for bacteria that love oxygen -- why?

d. Thioglycolate broth doesn't allow oxygen to be throughout so there is only a little oxygen at the top where the broth and the air meet so what kind of bacteria would love this?

Answer 1

Sol.a- Anaerobic bacteria grows in the absence of oxygen. The cultivation of strict anaerobic bacteria requires specialized precautions and equipment. The steps of anaerobic cultivation are-

1. A fluid thioglycolate medium is preferred. This medium consists of a reducing compound, sodium thioglycolate, that reduces the oxygen content of the medium which inturn creates an anaerobic environment for the growth of the bacteria.

2. Special anaerobic agar medium containing thioglycolate is poured into the bottom half of a Brewer anaerobic petri dish cover.

3. Solidification takes place after which the plate is inoculated and the Brewer cover sets in place.

4. The sodium thioglycolate in the medium uses up the oxygen in the small air space that creates anaerobic conditions.

Sol.b- Nutrient agar is used mainly for aerobic microbes, fungi, nonfastidious microbes and Thioglycolate medium is specifically used in preparation of anaerobic cultures.

Sol c- Nutrient agar is a general purpose medium for the cultivation of nonfastidious microorganisms. This medium can preserve microbial cultures. Oxygen loving microbes prefer nutrient agar because this medium provides the adequate resources and the suitable environment for the microbes to survive and helps in the proper growth.