| Technique | VOGES PROSKAUER |
| Principle | The Voges-Proskauer test detects the
presence of acetoin or acetyl-methyl-carbinol which is an
intermediate in the formation of 2,3, butanediol. The VP test is used primarily for the identification of enterics and the method can be performed in many ways. Long periods of incubation are preferable( up to 10 days). some enterics are negative when grown at 37 C but are positiv when grown at 30 C. Some coliforms,Bacillus species and staphylcocci take acetylmethylcarbinol and break it down for use as a carbon source. See also methyl red and acetylmethylcarbinol. The V-P test correlates with the Malonate test see also IMVIC test |
| Cautions | |
| Method | Inoculate MR VP medium and incubate at 30 C for 5 days or 37 C for 2 days. Test with methyl red and then add 0.6 ml of alpha napthol solution(about 15 drops) and 0.2 ml of 40 % KOH ( about 10 drops). Shake and examine for the red colour of a positive reaction after 15 min and 1 hour. |
| Results | A positive reaction is the development of a red colour after l5-60 min. Under alkaline conditions and in the presence of oxygen, acetyl-methyl-carbinol is oxidized to diacetyl which reacts with creatine to give a red colour. Creatine is present in peptone. |
| Positive control | Enterobacter cloacae |
| Negative control | Escherichia coli |
| Reagents | |
| Reference | B.P. Eddy (1961) The Voges Proskaur reaction and its significance: a review J. Appl Bacteriol 23:216 |