|Show all biochemical tests|
Bacteria, which have aerobic respiration, often have cytochrome c and a cytochrome c oxidase. The presence of these components can in combination with other methods be used for typing. A commersial test, which contains an artificial electron acceptor (N, N, N', N'-tetramethyl-p-phenylenediamine, see Fig. 1), is often used. This artificial electron acceptor change colour depending upon redox state. The substance is also referred to as a redox indicator and it can be oxidized by the oxidized form of cytochrome c. Cytochrome c oxidase is the last enzyme of the electron transport chain, where it normally reduces oxygen to water and pump protons to the outside according to the following net reaction:
Note that the oxidase reagent is not stable after that the ampoule has been opened. It may be used for a couple of hours, but eventually it will be oxidized by the oxygen in the air.
The oxidase test is used for identification of gram negative bacteria. For instance to identify members of the family Enterobacteriaceae, which are oxidase negative, except members of the genus Plesiomonas (oxidase positive). Members of the family Pseudomonadaceae, and the genera Aeromonas and Campylobacter are oxidase positive.
|New article about VetBact in SVT|
In the last year's last issue of "Svensk Veterinär- tidning" (SVT), there is an article about changes and updates that have been made during later years.Published 2018-01-11. Read more...