Which organisms can survive in both the presence and absence of oxygen?

The organisms that can survive in both the presence and absence of oxygen are known as facultative anaerobes. These organisms have the ability to utilize oxygen for aerobic respiration when it is available, which allows them to produce energy more efficiently. However, when oxygen is not present, facultative anaerobes can switch to anaerobic respiration or fermentation to generate energy. This versatility enables them to thrive in varying environmental conditions.

In contrast, obligate anaerobes are only able to survive in environments devoid of oxygen and are often harmed or killed by its presence. Obligate aerobes, on the other hand, require oxygen to survive and cannot grow in its absence. Microaerophiles necessitate low levels of oxygen to grow and are typically inhibited by atmospheric levels of oxygen. Thus, facultative anaerobes are unique in their adaptability to both aerobic and anaerobic conditions.