What term is used to describe organisms that cannot survive in the presence of oxygen?

The term for organisms that cannot survive in the presence of oxygen is "obligate anaerobes." These are microorganisms that are adapted to live in environments devoid of oxygen. Their metabolic pathways do not utilize oxygen and, in fact, may be inhibited or even toxic when exposed to it. Obligate anaerobes obtain energy through processes such as fermentation or anaerobic respiration, which do not rely on oxygen as an electron acceptor.

Understanding this concept is key when studying different metabolic classifications of organisms. In contrast, facultative anaerobes can switch between aerobic and anaerobic metabolic processes depending on the availability of oxygen, while obligate aerobes require oxygen to survive and thrive. Aerotolerant anaerobes can tolerate oxygen but do not use it for growth, highlighting the various adaptations organisms have evolved in relation to oxygen availability.