| VOGES-PROSKAUER TEST |
DESCRIPTION
Test checks for the presence of acetoin (acetyl methyl carbinol), butylene glycol and finally diacetyl resulted from
bacterial decomposition of carbon compounds (glucose). Diacetyl in the presence of strong KOH solution reacts
with proteins to give a pink coloration.
Test checks for the presence of acetoin (acetyl methyl carbinol), butylene glycol and finally diacetyl resulted from
bacterial decomposition of carbon compounds (glucose). Diacetyl in the presence of strong KOH solution reacts
with proteins to give a pink coloration.
Medium composition: peptone 5g, glucose 5g, K2HPO4 2g, distilled water
1000 ml.
Procedure:
Inoculate VP broth tube with one drop or loopful of fresh inoculum.
Incubate at 37 ˚C, 24-48 hours or until turbid growth is observed.
Add Barritt's reagent A (alpha naphthol) and reagent B (40% KOH).
Reaction is positive if a red color is seen within 30 minutes. Reaction
requires oxygen presence and it only appears on the surface of the
medium unless the tube is vigorously shaken.
Werkman published an improvement of VP technique, recommending the
utilization of the ferric chloride which hastens the oxidation of the
acetylmethyl
carbinol to diacetyl which reacts with peptone in an alkaline solution
to produce a copper coloration.
1000 ml.
Procedure:
Inoculate VP broth tube with one drop or loopful of fresh inoculum.
Incubate at 37 ˚C, 24-48 hours or until turbid growth is observed.
Add Barritt's reagent A (alpha naphthol) and reagent B (40% KOH).
Reaction is positive if a red color is seen within 30 minutes. Reaction
requires oxygen presence and it only appears on the surface of the
medium unless the tube is vigorously shaken.
Werkman published an improvement of VP technique, recommending the
utilization of the ferric chloride which hastens the oxidation of the
acetylmethyl
carbinol to diacetyl which reacts with peptone in an alkaline solution
to produce a copper coloration.
NOTES
For streptococcal identification weak reactions (pink or rust colors) are interpreted as positive.
For streptococcal identification weak reactions (pink or rust colors) are interpreted as positive.
REFERENCES:
1. Werkman C.H.: AN IMPROVED TECHNIC FOR THE VOGES-PROSKAUER TEST. J Bacteriol. 1930; 20(2): 121–
125.
2. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed. Ceres, Bucuresti.
3. Margaret Barnett, 1992. Microbiology Laboratory Exercises. Wm. C. Brown Publishers.
4. J. F. Gracey, D. S. Collins, Robert J. Huey: Meat hygiene. 1999; 375-376.
5. Murray, P.R., Baron, E. J., Jorgensen, J.J., Pfaller, M.A., and Yolken, R.H. Manual of Clinical Microbiology, 8th ed.
ASM Press: Washington, DC, 2003.
1. Werkman C.H.: AN IMPROVED TECHNIC FOR THE VOGES-PROSKAUER TEST. J Bacteriol. 1930; 20(2): 121–
125.
2. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed. Ceres, Bucuresti.
3. Margaret Barnett, 1992. Microbiology Laboratory Exercises. Wm. C. Brown Publishers.
4. J. F. Gracey, D. S. Collins, Robert J. Huey: Meat hygiene. 1999; 375-376.
5. Murray, P.R., Baron, E. J., Jorgensen, J.J., Pfaller, M.A., and Yolken, R.H. Manual of Clinical Microbiology, 8th ed.
ASM Press: Washington, DC, 2003.
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