Why strict aerobes oxidase-positive?
An aerobic organism or aerobe is an organism that has an oxygen based metabolism. Aerobes, in a process known as cellular respiration, use oxygen to oxidize substrates (for example sugars and fats) in order to obtain energy. Strict, or obligate, aerobes require oxygen, while facultative aerobes can use oxygen, but also have other options, such as nitrogen. An oxidase is any enzyme that catalyzes an oxidation/reduction reaction involving molecular oxygen (O2) as the electron acceptor. In these reactions, oxygen is reduced to water (H2O) or hydrogen peroxide (H2O2). In microbiology, the oxidase test is used as a phenotypic character for the identification of bacterial strains; it determines whether a given bacterium produces cytochrome oxidases (and therefore utilizes oxygen with an electron transfer chain). Therefore, a strict aerobe will always test positive for oxidase.
