Question

Explain how microbes are classified on the basis of oxygen requirements.

Answer 1

Microbes are classified according to their oxygen requirements for their nutrients and growth. According to Oxygen requirement microbes are classified into following types-

1. Aerobes:- They mainly grows in air, which contains Oxygen in higher amount. Here 'Oxygen' is functioned as terminal electron acceptor.

Aerobic organisms further classified into Obligate aerobes for the absolute requirements of Oxygen to grow.

2. Anaerobes:- Organisms of this group can't grow in presence of Oxygen. Their metabolism is a fermentative type in which they reduces organic compound to various end products like alcohol, organic acid etc.

Anaerobes are also classified into following-

A. Obligate anaerobes:- They grow under the condition of high reducing intensity. For these microbes Oxygen is very toxic to them.

B. Facultative anaerobes:- These microorganisms has the capacity for growing under both aerobic and anaerobic condition. They use Oxygen as a terminal electron acceptor.

C. Aerotolerant anaerobes:- These microorganisms has the capacity to grow in the air which contains Oxygen.

3. Microaerophiles:- These microbes can grow under reduced Oxygen and higher amount of Carbon dioxide (8-10%). Higher level of Oxygen may be harmful to them.

4.Capnophiles:- They require increased concentration of CO₂(5-10%) and high amount of Oxygen(10-15%).