Dehydrated culture media
Rothe Broth (Glucose Broth With Azide)
For the quantitative determination of fecal enterococci.
- Cat. No.
- LC-1238
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
Rothe Broth (Glucose Broth With Azide) is a selective medium recommended by Mallmann and Seligmann for the quantification of enterococci in water, food and other materials suspected of being contaminated by waste waters. Enterococci are the best indicators of fecal contamination in water as Escherichia coli is very resistant to chloride.
Key features
Applications
Selective enumeration of enterococci.
Preparation
34.7 g in one liter of distilled water; heat until boiling point, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
The presence of enterococci is an indicator for fecal contamination, especially when it occurred a long time ago and the less resistant coliform bacteria, including Escherichia coli, may already be dead when the analysis is carried out.
Peptone mixture and casein peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Glucose is the fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and osmotic balance. The use of sodium azide to selectively inhibit Gram-negative bacteria first appeared in the studies of Edwards (1938) on the isolation of Streptococcus agalactiae; it was later shown that sodium azide can also be used for the isolation of enterococci from water.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Yellowish brown |
| Final pH (25 °C) | 7.2 ± 0.2 |
| Amount per litre | 34.7 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Glucose | 7.5 |
| Beef extract | 4.5 |
| Peptone mixture | 15 |
| Sodium azide | 0.2 |
| Sodium chloride | 7.5 |
Preparation and use
Preparation
Suspend 34.7 grams of the medium in one liter of distilled water (69.4 grams if double concentration is desired). Mix well and dissolve by heating with frequent agitation until boiling point. DO NOT OVERHEAT. Dispense into appropriate containers and sterilize in autoclave at 121 °C for 15 minutes.
Instructions for use
Rothe Broth is ideal for the enumeration of enterococci by the serial dilution method. Inoculate 10 mL of the sample in 10 mL tubes of double-strength Rothe Broth (or 1 mL of the sample in 10 mL of a single-strength medium). Use 5 tubes for each dilution (according to Mallmann and Seligmann). Incubate all tubes at 35 ± 2 °C for 24-48 hours. Confirmation of fecal enterococci is obtained by the subsequent inoculation of positive tubes into EVA Broth (LC-1230).
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 24-48 h.
| Microorganism | Specification |
|---|---|
| Enterococcus faecalisATCC 19433 | Good growth |
| Escherichia coliATCC 25922 | Inhibited growth |
| Staphylococcus aureusATCC 25923 | Inhibited growth |
| Enterococcus faecalisATCC 29212 | Good growth |
Bibliography
- Mallmann W.L. Seligmann E.B. AJPH, 1950. 40 286-289
- Standard Methods for the Examination of Water and Wastewater. Eleventh Edition APHA Inc. New-York 1960
- Edwards S.J. (1933) J. Comp. Path Therap., 46.211.
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