User talk:Shyam.more

Oxidase Test

The oxidase test can be used in the identification of GNB to distinguish non-fermenters (oxidase positive) from fermenters (oxidase negative).

The oxidase test checks for the presence of the enzyme indophenol oxidase. Tetramethyl-para-phenylenediamine (oxidase reagent) will be oxidized in the presence of atmospheric oxygen by indophenol oxidase causing the formation of a dark-purple compound known as indophenol.

Prepare a fresh solution of oxidase reagent (N, N, N, N, -Tetraethyl l-p- phenylenediamine dihydrochloride) by adding a loopful of it to about 3 ml of sterile distilled water or saline. Do not use if it becomes blue. For use wet a filter paper disc (what Mann N0.1) in a sterile Petri dish with a few drops of oxidase reagent and apply the test culture (Test culture should be grown on a medium free of glucose or nitrate) with a platinum loop (and not nichrome wire loop), glass rod or swab stick. The appearance of dark purple color indicates a positive reaction. Positive control      :    Pseudomonas aeruginosa. Negative control     :    Escherichia coli.