Which type of organisms cannot survive in the presence of oxygen?

Obligate anaerobes are organisms that are specifically adapted to live in environments devoid of oxygen. They rely on anaerobic respiration or fermentation processes to generate energy. For these organisms, the presence of oxygen can be toxic, leading to the production of reactive oxygen species that can damage cellular components. Unlike facultative anaerobes, which can switch between aerobic and anaerobic metabolism, obligate anaerobes are entirely dependent on anaerobic conditions for their survival.

Facultative anaerobes can thrive in both the presence and absence of oxygen, while aerobes require oxygen for their metabolic processes. Photoautotrophs are organisms that use light energy to produce organic compounds, typically relying on oxygen in their metabolic pathways. Thus, the characteristics of obligate anaerobes make them uniquely suited to environments where oxygen is absent.