| Fermentation of Carbohydrates and Polyalcohols |
DESCRIPTION
Test consists in cultivating a bacteria strain in a medium containing a single fermentable nutrient (a carbohydrate or
a polyalcohol) 0.5-1% and a pH indicator for acid production. Nutritive non-fermentable substances are also added
to support growth. As pH indicator may be used Phenol red, Bromthymol blue or Brom cresol purple.
Test consists in cultivating a bacteria strain in a medium containing a single fermentable nutrient (a carbohydrate or
a polyalcohol) 0.5-1% and a pH indicator for acid production. Nutritive non-fermentable substances are also added
to support growth. As pH indicator may be used Phenol red, Bromthymol blue or Brom cresol purple.
MATERIALS
Simplest medium for fermentation testing is Peptone water (proteose
peptone 2g, NaCl 0.5 g, H2O ad 100 ml) supplemented with a
carbohydrate or polyalcohol 1%.
Next step is to add 1.2 ml of bromthymol blue solution (bromthymol blue 1
g, NaOH n/10 25 ml , distilled water 475 ml) in 100 ml peptone water. If
using phenol red then add 1 ml phenol red solution 2% in 100 ml peptone
water.
A demonstration of phenol red preparation is available in video section.
PROCEDURE
Inoculate the medium and incubate it at 37 °C, 24 hours.
A yellow color after 24 hours show a positive result. Reaction is negative if
medium color is red-orange (phenol red) or blue-green (bromthymol blue).
Fermentation with gas production may also be tested introducing a
Durham tube in the carbohydrate broth. A demonstration of gas
production by glucose fermenting bacteria is available in video section.
Simplest medium for fermentation testing is Peptone water (proteose
peptone 2g, NaCl 0.5 g, H2O ad 100 ml) supplemented with a
carbohydrate or polyalcohol 1%.
Next step is to add 1.2 ml of bromthymol blue solution (bromthymol blue 1
g, NaOH n/10 25 ml , distilled water 475 ml) in 100 ml peptone water. If
using phenol red then add 1 ml phenol red solution 2% in 100 ml peptone
water.
A demonstration of phenol red preparation is available in video section.
PROCEDURE
Inoculate the medium and incubate it at 37 °C, 24 hours.
A yellow color after 24 hours show a positive result. Reaction is negative if
medium color is red-orange (phenol red) or blue-green (bromthymol blue).
Fermentation with gas production may also be tested introducing a
Durham tube in the carbohydrate broth. A demonstration of gas
production by glucose fermenting bacteria is available in video section.
REFERENCES
1. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed.
Ceres, Bucuresti.
1. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed.
Ceres, Bucuresti.
This method can be used for testing fermentation of glucose, lactose,
saccharose, maltose, trehalose, raffinose, xylose, arabinose, rhamnose,
sorbose, starch, dextrin, inulin, glycogen, glycerol, erythritol, adonitol,
dulcitol, mannitol, sorbitol, inositol, salicin, esculin and others.
saccharose, maltose, trehalose, raffinose, xylose, arabinose, rhamnose,
sorbose, starch, dextrin, inulin, glycogen, glycerol, erythritol, adonitol,
dulcitol, mannitol, sorbitol, inositol, salicin, esculin and others.
| Glucose medium with Phenol red and Durham tubes for fermentation gas capture |
2. Margaret Barnett, 1992. Microbiology Laboratory Exercises. Wm. C. Brown Publishers.
3. 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.
3. 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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