Dehydrated culture media
KF Streptococcal Broth
For the isolation of Enterococcus faecalis.
- Cat. No.
- LC-1346
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
KF (Kenner Fecal) Streptococcal Broth was developed by Kenner et al. for the detection and enumeration of enterococci in waters. They found that this formulation was superior to other liquid media for the recovery of enterococci in Most Probable Number (MPN) test systems.
Key features
Applications
Selective enumeration of enterococci.
Industry
Water.
Preparation
56.4 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 10 minutes.
Principles and uses
The medium is not specific for the presumptive identification of group D streptococci. The addition of 1% TTC (2,3,5-triphenyltetrazolium chloride) in the membrane filter procedure causes the enterococci to have a deep red color as a result of tetrazolium reduction to formazan, an insoluble red pigment, by actively growing microbial cells.
Peptone mixture provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Maltose and Lactose are the fermentable carbohydrates as carbon and energy sources. Sodium glycerophosphate is a buffering agent. Sodium azide is a selective agent that inhibits Gram-negative bacteria. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bromocresol purple is the pH indicator with a color change from purple to yellow.
The presence of intestinal enterococci is an indicator for faecal contamination, especially when the contamination occurred long before, and the less resistant coliform bacteria, including Escherichia coli, are already dead when the analysis is carried out.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Purple |
| Final pH (25 °C) | 7.2 ± 0.2 |
| Amount per litre | 56.4 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bromocresol purple | 0.015 |
| Lactose | 1 |
| Maltose | 20 |
| Sodium azide | 0.4 |
| Sodium chloride | 5 |
| Sodium glycerophosphate | 10 |
| Yeast extract | 10 |
| Proteose peptone No. 3 | 10 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 56.4 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121 °C for 10 minutes. Cool to 45-50 °C and aseptically add two vials of 1% TTC Supplement (LC-6030), previously reconstituted in 5 mL of sterile distilled water. Homogenize gently and dispense into sterile containers.
Instructions for use
Inoculate and incubate at 35 ± 1 °C in an atmosphere saturated with water vapour for 46-48 hours.
Quality control
Microbiological test
Incubation conditions: 35 ± 1 °C / 46-48 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Klebsiella aerogenesATCC 13048 | Total inhibition | |
| Enterococcus faecalisATCC 19433 | Good growth | Red colonies |
| Escherichia coliATCC 25922 | Total inhibition | |
| Enterococcus faecalisATCC 29212 | Good growth | Red colonies |
Bibliography
- Kenner, Clark and Kabler. 1961. Appl. Microbiol. 9.15.2.
- MacFaddin. 1985. Media for isolation-cultivation-identification-maintenance of medical bacteria, vol. 1. Williams & Wilkins, Baltimore, Md.
- Facklam and Moody. 1970. Appl. Microbiol. 20.245.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
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