Ready-to-use media
Lactose Sulphite Broth (C+) ISO
Liquid medium for the determination of H₂S production by Clostridium perfringens according to ISO standard.
- Cat. No.
- LC-4135
- Category
- Ready-to-use media
- Format
- 20 tubes
- Storage
- 8 to 25 °C
- Minimum guaranteed shelf life
- 4 months
- Standards
- ISO 7937
This is a simple medium that selects C. perfringens over other sulfite-reducing clostridia by their ability to produce gas from lactose, at 46 °C. C. paraperfringens also has this ability, however this microorganism is very rare in food samples.
Key features
Applications
Confirmation of Clostridium perfringens.
Industry
Food.
Standards
ISO 7937.
Presentation
20 tubes, 16 x 113 mm, with Durham tube; filling 9 ± 0.1 mL.
Description and technique
All of the freshly prepared or reconstituted media tubes are inoculated in duplicate with 5 drops of fresh thioglycollate culture in sterile conditions. Tubes are incubated in aerobic conditions at 46 °C for a period of 18-24 hours. Tubes are incubated in aerobic conditions at 46 ± 1 °C for a period of 18-24 hours. C. perfringens presence is observed by an iron sulfide precipitate appearing in the tubes. It indicates sulfite-reducing activity. Accumulation of gas in the Durham tubes is a sign of lactose fermentation.
It is possible that air bubbles are generated in the Durham tube during the transport. If air bubbles are present in the Durham tube prior to inoculation, the tube should be inverted until the air is released from the Durham tube. Failure to remove air bubbles prior to inoculation may result in reading the result as a false-positive reaction in gas production.
Presentation
| Presentation | 20 tubes, 16 x 113 mm, with Durham tube |
|---|---|
| Filling | 9 ± 0.1 mL |
| Packaging | 16 x 113 mm glass tubes, ink labelled, with Durham tube and metal non-injectable cap. 20 tubes per box. |
Composition
| Ingredient | g/L |
|---|---|
| Tryptone | 5.000 |
| Yeast extract | 2.500 |
| Sodium chloride | 2.500 |
| Lactose | 10.000 |
| L-Cysteine | 0.300 |
| Sodium bisulfite | 0.750 |
| Ammonium ferric citrate | 0.625 |
Quality control
Physical/chemical control
| Color | Pale yellow |
|---|---|
| pH | 7.1 ± 0.2 at 25 °C |
Microbiological control
Inoculate: practical range 100 ± 20 CFU; min. 50 CFU (productivity) / 10⁴-10⁶ (selectivity).
Microbiological control according to ISO 11133:2014/Amd 1:2018.
Aerobic incubation at 46 ± 1 °C for 18-24 h.
| Microorganism | Growth |
|---|---|
| Clostridium perfringensATCC 13124, WDCM 00007, NCTC 8237 | Good - H₂S (+) - gas (+) |
| Clostridium perfringensATCC 10543, WDCM 00174 | Good - H₂S (+) - gas (+) |
| Bacillus subtilisATCC 6633, WDCM 00003 | Inhibited |
Sterility control
Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.
Check at 7 days after incubation in same conditions.
Bibliography
- ISO Standard 7937 (2004) Microbiology of food and animal feeding stuffs. Horizontal method for enumeration of Clostridium perfringens. Colony count technique.
- ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
- PASCUAL ANDERSON, Mª R. (1992) Microbiología Alimentaria. Díaz de Santos. Madrid.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
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Tracked shipment
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Frequently asked questions
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