Product Code TBL 030
Description
Certain bacteria posses either cytochrome oxidase or indophenol oxidase (an iron-containing haemoprotein), which
catalyzes the transport of electrons from donor compounds (NADH) to electron acceptors (usually oxygen). In the
oxidase test, a colourless dye such as N, N-dimethy-p-phenylenediamine serves as an artificial electron acceptor for the
enzyme oxidase. The dye is oxidized to form indophenol blue, a coloured compound. The test is useful in the initial
characterization of aerobic gram-negative bacteria of the genera Aeromonas, Plesiomonas, Pseudomonas,
Campylobacter and Pasteurella. Oxidase discs are sterile filter paper discs impregnated with N, N-dimethyl-pphenylenediamine
oxalate, ascorbic acid and a-naphthol. These discs overcome the neccessity of daily preparation of
fresh reagent. Gordon and McLeod introduced oxidase test for identifying gonococci based upon the ability of certain
bacteria to produce indophenol blue from the oxidation of dimethyl-p-phenylenediamine and a-naphthol. Gaby and
Hadley introduced a more sensitive method by using N, N-dimethyl-p-phenylenediamine oxalate where all
staphylococci were oxidase negative. In a positive reaction the enzyme cytochrome oxidase combines with N,Ndimethyl-
p-phenylenediamine oxalate and a-naphthol to form the dye, indophenol blue.
Principle
For detection of oxidase production by microorganisms.
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