| Technique | DECARBOXYLASE ,(/,)/,( |
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| Principle | Decarboxylases for amino acids are characteristic for different bacteria within the Enterobacteriacae. Arginine dihydrolyase,lysine glutamic acid and ornithine decarboxylases can be detected by a colour change of an indicator. | ||||||||||||||||||||||||||||||||||||
| Cautions | These tests should not be used with
organisms of unknown identity but as a taxonomic tool. Arginine is hydrolysed by some streptococci and corynebacteria |
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| Method | .From a plate culture, lightly inoculate tubes of the five media (arginine, lysine, glutamic acid, ornithine and control) through the paraffin layer. Incubate and examine daily for up to four days. | ||||||||||||||||||||||||||||||||||||
| Results | The media first become yellow due to acid production from the glucose; later is decarboxylation occurs, the medium become violet. The control should remain yellow. When a positive reaction is obtained with arginine, the medium may be tested with Nessler's reagent for the presence of ammonia. In the absence of urease, the formation of ammonia indicates that the arginine dihydrolase system was used | ||||||||||||||||||||||||||||||||||||
| Positive & Negaitive Controls |
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| Reagents | |||||||||||||||||||||||||||||||||||||
| Reference |