1. Glucose (dextrose) broth:
- 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.