Dehydrated culture media
SPS Agar (Sulfite Polymyxin Sulfadiazine)
For the isolation and enumeration of Clostridium perfringens from food and all types of foodstuffs.
- Cat. No.
- LC-1082
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
- Also available
- Ready-to-use medium, 2 formats (LC-4255)
SPS Agar (Sulfite Polymyxin Sulfadiazine) is a moderately selective medium to recover Clostridium perfringens from fresh or preserved foods and food ingredients.
Key features
Applications
Selective enumeration of Clostridium perfringens.
Industry
Food.
Preparation
39.7 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 118 °C for 15 minutes.
Principles and uses
The medium was modified by Angelotti, incorporating sulfadiazine and polymyxin B sulfate into the more recent Mossel formula for the recovery of Clostridium perfringens.
Casein peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Ferric citrate and sodium sulfite are H₂S indicators. C. perfringens reduces the sulfite to sulfide, which in turn reacts with the iron and forms a black iron sulfide precipitate, seen as black colonies. Polymyxin B sulfate and sulfadiazine are inhibitors to organisms other than Clostridium spp. Bacteriological agar is the solidifying agent.
A few microorganisms other than C. perfringens also grow on SPS Agar, so it is best to perform a Gram stain and look for spores. Many common microorganisms are totally or partially inhibited, but if they develop, they generally do not form black colonies nor spores, nor do they reduce nitrate, and are non-motile Gram-positive vegetative bacilli.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Amber, slightly opalescent |
| Final pH (25 °C) | 7.0 ± 0.2 |
| Amount per litre | 39.7 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bacteriological agar | 13 |
| Casein peptone | 15.5 |
| Polymyxin B sulfate | 0.01 |
| Sodium sulfite | 0.5 |
| Sulfadiazine | 0.12 |
| Yeast extract | 10 |
| Ferric citrate | 0.5 |
Preparation and use
Preparation
Suspend 39.7 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 118 °C for 15 minutes.
Instructions for use
- Prepare in a homogenizer, or other equipment, the material samples and make serial dilutions.
- Dispense the inoculum into a sterile Petri dish.
- Pour the medium cooled to 50-55 °C over the inoculum and gently mix the inoculum and medium.
- It is possible to dispense the medium into tubes and inoculate them by the stab method.
- Incubate anaerobically (the authors used a mixture of 90% nitrogen and 10% CO₂) at 35 ± 2 °C for 24-48 hours.
- The lack of motility and the capacity to reduce nitrate can be determined on Indole Nitrate Medium (LC-1504) with 2 g/L of added agar.
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 24-48 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Clostridium perfringensATCC 13124 | Good growth | Black colony |
| Clostridium sporogenesATCC 19404 | Moderate growth | Black colony |
| Escherichia coliATCC 25922 | Inhibited growth | |
| Staphylococcus aureusATCC 6538 | Moderate/inhibited growth | White colony |
Bibliography
- Angelotti, Nall, Foter and Lewis. Applied Microbiol. 10: 193. 1962.
- Mossel. J. Sci. Agr. 10: 662. 1959.
- Mossel, de Bruin, Van Diepen, Vendrig and Zoutwelle. J. Applied Bact. 19: 142. 1956.
What you receive
The product
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