aerobes

An aerobe is an organism that requires oxygen for growth and energy production. In aerobes, energy is generated mainly by aerobic respiration, a metabolism that uses glycolysis, the citric acid cycle, and oxidative phosphorylation, with molecular oxygen serving as the terminal electron acceptor. This pathway yields more ATP per glucose than anaerobic processes, but it also generates reactive oxygen species that can damage proteins, lipids, and DNA. To cope with oxidative stress, aerobes maintain antioxidant defenses such as superoxide dismutase, catalase, and peroxidases.

Classification generally distinguishes obligate (strict) aerobes, which require oxygen for growth; microaerophiles, which need only low levels of oxygen; and organisms that are facultative anaerobes, which can grow with or without oxygen but favor aerobic metabolism when oxygen is available.

Ecology and significance: Aerobes are common in oxygen-rich environments, including soil, surface water, and animal tissues. They drive decomposition and nutrient cycling and are used in industrial processes such as aerobic wastewater treatment and bioremediation. Some obligate aerobes are notable human pathogens, while many aerobes contribute beneficially to biotechnology and research.

Examples include Mycobacterium tuberculosis and Pseudomonas aeruginosa (obligate aerobes), Helicobacter pylori (microaerophile), and Escherichia coli (facultative anaerobe).