Question

Which of the following types of bacteria are most affected by toxic oxygen byproducts?

A.obligate aerobes

B.microaerophiles

C.facultative anaerobes

D.aerotolerantanaerobes

E.obligate anaerobes

explain thank you.

Answer 1

Explination:

Oxygen as such is an essential requirement for majority of micro-organisms with exceptions of its toxicity to some specific microbes. Based on the absolute, relative or non-requirement of O₂ molecule to a microbe (bacteria), they are divided into below classes:

1. Obligate aerobes: They need oxygen compulsorily for their growth e.g. Pseudomonas, Mycobacterium tuberculosis etc.

2. Microaerophiles: They have capacity to grow in a relatively lower levels of oxygen (5-10%) but under higher levels of carbon dioxide (8-10%). e.g. Helicobacter pylori

3. Facultative anaerobes: These bacteria can grow under both in the presence of oxygen (aerobic) and in the absence of oxygen (Anaerobic) conditions e.g. Staphylococcus aureus

4. Aerotolerant anaerobes: These normally grow abundantly in the absence of oxygen (Anaerobic) but they can still grow if exposed to oxygen conditions e.g. Clostridium carnis

5. Obligate anaerobes: They grow under reducing conditions and they do not use oxygen for their energy metabolic reactions, thus oxygen is toxic for their growth e.g. Clostridium species. These bacteria form toxic hydrogen peroxide once they get exposed to oxygen and thus getting killed.

Therefore, based on the above facts, it is evident that correct option is E (obligate anaerobes)