• Glucose broth is an enriched fluid medium used to culture a variety of nutritionally demanding microorganism. It is used in the preparation of Loefflers serum medium.
• It can be prepare from the dehydrated medium available from oxoid Ltd and other manufacturers of culture media.

Composition of glucose broth

• Lab-lemco powder………………………3 gm/ltr
• Tryptose………………………………….10 gm/ltr
• Dextrose (glucose)……………………….5 gm/ltr
• Sodium chloride…………………………5 gm/ltr

Preparation of glucose broth:

• The medium is used at a concentration of 22.3 grams in every 100 ml of distilled water.
• Prepare as instructed by the manufacturer.
• Dispense the well-mixed medium in 5 ml amounts in screw-cap Bijou bottles. Sterilize by autocalving (with cap loosened) at 121°C for 15 minutes.
• When cool, tighten the bottle caps.
• Date the medium and give it a batch number.

Quality control

• pH of medium: this should be within the range the range pH 7.0-7.4 at room temperature.
• Store in a cool dark place.

Use of glucose broth:

• Used as enrichment media for various microorganisms
• *Inoculate the broth with a sterile wire loop or Pasteur pipette depending on the specimen.

2. Glucose (dextrose) phosphate peptone water: composition. Preparation and uses

• Glucose phosphate peptone water is fluid medium used in the Voges-Proskauer (V-P) test and the methyl  red test

composition of glucose phosphate peptone water

• Peptone…………………………………0.5 g
• Glucose (dextrose)………………………0.5 g
• di- potassium hydrogen phosphate……..0.5 g
• Distilled water…………………………..100 ml

Preparation of glucose phosphate peptone water:

• Dissolve the peptone and phosphate salt in the water by steaming. When cool, filter and adjust the pH to 7.5
• Add the glucose and mix well
• Dispense the medium in 2 ml amounts in small screw-cap tubes or bottles.
• Sterilize by autoclaving (with cap loosened) at 115°C for 10 minutes. When cool tighten the container tops.

Quality control

• pH of medium: this should be within the range of pH 7.4-7.6 at room temperature.
• Store the medium in a cool, dark place or at 2-8°C

Uses of glucose phosphate peptone water:

• Used in Methyl red test and  Voges-Proskauer test medium

3. Glycerol broth: composition, preparation and uses

• Glycerol broth is used to preserve control species.

Composition of glycerol broth

• Nutrient broth…………………………….84 ml
• Glycerol…………………………………..16 ml

Preparation of glycerol broth:

• Prepare the nutrient broth
• Add the glycerol and mix well. Dispense in 5 ml amounts in screw-cap tubes or bottles.
• Sterilize by autoclaving (with cap loosened) at 115°C for 20 minutes. When cool tighten the container caps.
• Date the medium and give it a batch number

Quality control

• pH of medium: this should be within the range of pH 7.2-7.6 at room temperature.
• Store in a cool dark place or 2-8°C.

Use of glycerol broth:

• Used to test microorganism for their glycerol utilizing activity.

Glucose broth, glucose phosphate peptone water and Glycerol broth

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