Basically, this is a test to see if an organism is an aerobe. It is a check for the presence of the
electron transport chain that is the final phase of aerobic respiration. Normally, oxygen is the
final electron acceptor for this system. In the oxidase test, an artificial final electron acceptor
(N,N,N’,N’-tetramethyl phenylenediamine dihydrochloride) is used in the place of oxygen. This
acceptor is a chemical that changes color to a dark blue/purple when it takes the electron from
the last element (cytochrome oxidase) in the electron transport chain.