The term aerotolerant anaerobe refers to an organism that
does not use oxygen but tolerates it.
tolerates normal atmospheric CO2 levels.
requires less oxygen than is present in air.
Requires more oxygen than is present in air.
The correct answer and explanation is :
Correct Answer:
Does not use oxygen but tolerates it.
Explanation:
An aerotolerant anaerobe is a type of microorganism that does not require oxygen for growth and does not use oxygen in its metabolic processes, but it can survive and grow in the presence of oxygen. This distinguishes it from other types of anaerobes and aerobes based on their relationship with oxygen.
Let’s explore the different types of oxygen-related microbial classifications to clarify:
- Obligate Aerobes need oxygen to grow because they rely on aerobic respiration, which uses oxygen as the final electron acceptor in the electron transport chain.
- Obligate Anaerobes cannot survive in the presence of oxygen because it is toxic to them. They often lack the necessary enzymes like superoxide dismutase and catalase to neutralize reactive oxygen species.
- Facultative Anaerobes can grow with or without oxygen. They prefer oxygen if it’s available, using aerobic respiration, but can switch to fermentation or anaerobic respiration in its absence.
- Microaerophiles require oxygen but at lower levels than are present in the atmosphere. High oxygen concentrations can harm them.
- Aerotolerant Anaerobes, like the one described in the question, do not use oxygen at all. However, they can survive in its presence because they have enzymes like superoxide dismutase that protect them from oxidative damage. They rely on fermentation for energy production regardless of oxygen presence.
A common example of an aerotolerant anaerobe is Lactobacillus, which is found in many fermented foods and the human gut.
Summary:
The term aerotolerant anaerobe correctly refers to an organism that does not use oxygen but can tolerate its presence. It relies solely on fermentation for metabolism, but its ability to survive in oxygen-rich environments makes it unique among anaerobes.