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Lactose Sulfite (LS) Broth • Selective Medium for C. perfringens
$45.00 AUD
AuSaMicS Life Science • Culture Media
Lactose Sulfite Broth
LS Broth • Selective enrichment medium for Clostridium perfringens
Lactose Sulfite Broth is a highly selective liquid medium developed for the detection and presumptive enumeration of Clostridium perfringens, particularly in foods, water, and related microbiological test samples. The medium combines lactose fermentation with sulfite reduction to generate a clear, practical presumptive reaction based on blackening, acid production, and gas formation.
AS-1264 Selective Broth ✓ Food Microbiology ⬛ Blackening Reaction
Target Organism: C. perfringens Incubation: 46 ± 0.5 °C Available: COA + TDS + SDS
C. perfringens Screening Medium
Blackening - sulfite reduction reaction
Gas Production - Durham tube indication
Acid Formation - lactose fermentation
MPN Compatible - single and double strength use
Reference Method Support - food microbiology workflows
Typical Positive Result
Entire medium blackened within 18–24 h
🔬 Product Overview
Lactose Sulfite Broth is designed for the detection and presumptive enumeration of Clostridium perfringens, including heat-resistant strains recovered from food and environmental testing workflows. It is especially useful in MPN-based methods and confirmation steps following recovery on selective solid media such as TSC or SFP agar.
The selectivity of the medium is based on the ability of actively growing C. perfringens to reduce sulfite, which reacts with the ferric salt system to produce a blackened medium. At the same time, lactose fermentation contributes acid and gas production, giving a highly characteristic presumptive reaction.
This medium is widely associated with food microbiology reference workflows for the detection and enumeration of sulfite-reducing Clostridium perfringens.
Principle of the Medium
Lactose Sulfite Broth combines nutrient support, carbohydrate fermentation, and sulfite reduction in one selective enrichment system:
Growth of target organism
↓
Sulfite reduction
↓
Reaction with ferric citrate / ferric ammonium citrate
↓
Blackening of the medium
Lactose fermentation
↓
Acid + gas production
↓
Sulfite reduction
↓
Reaction with ferric citrate / ferric ammonium citrate
↓
Blackening of the medium
Lactose fermentation
↓
Acid + gas production
Interpretation: intense blackening of the broth, with gas in the Durham tube and acid production, is considered a typical presumptive positive reaction.
Applications
Food Testing
Detection and MPN enumeration of C. perfringens in foods such as meat products, spices, vegetables, and infant formula.
💧 Water & Environmental Samples
Useful in selective enrichment workflows for presumptive recovery of sulfite-reducing Clostridium perfringens from water and related samples.
📊 MPN Workflows
Supports most probable number enumeration using both single-strength and double-strength formats.
✅ Confirmation Support
Suitable for confirmation of suspected heat-resistant C. perfringens isolates recovered from selective agar methods.
📊 Key Features
High Selectivity
Designed for highly specific presumptive detection of C. perfringens.
Designed for highly specific presumptive detection of C. perfringens.
Typical Blackening Reaction
Reduction of sulfite with ferric salt indicator gives a strong visual readout.
Reduction of sulfite with ferric salt indicator gives a strong visual readout.
MPN Ready
Double-strength versions are suitable for dilution and enumeration schemes.
Double-strength versions are suitable for dilution and enumeration schemes.
Rapid Presumptive Readout
Typical positives are generally recognizable within 18–24 hours at elevated incubation temperature.
Typical positives are generally recognizable within 18–24 hours at elevated incubation temperature.
🧪 Composition (per litre, single strength)
Final pH: 7.1 ± 0.2 at 25 °C
🧭 Preparation
- Dissolve all components except sodium sulfite and ferric citrate in approximately 900 mL purified water.
- Adjust the pH to 7.1.
- Add sodium sulfite and ferric citrate, preferably dissolved separately.
- Make up to 1 litre with purified water.
- Dispense into tubes with Durham tubes:
- 10 mL for single-strength use
- 5 mL for double-strength use
- Autoclave at 121 °C for 10 minutes only.
💡 Typical Reaction Pattern
Positive
Intense blackening of the entire medium, gas in the Durham tube, and acid production.
Intense blackening of the entire medium, gas in the Durham tube, and acid production.
Negative
Medium remains beige to light brown, with no blackening and no gas.
Medium remains beige to light brown, with no blackening and no gas.
📋 Technical Specifications
| Product Name | Lactose Sulfite Broth |
| Catalogue Number | AS-1264 |
| Medium Type | Selective broth medium |
| Primary Use | Presumptive detection and enumeration of C. perfringens |
| Reaction Readout | Blackening, gas, acid |
| Incubation Temperature | 46 ± 0.5 °C |
| Incubation Time | 18–24 hours |
| Single / Double Strength | Suitable for both |
| Storage | Prepared tubes: 2–8 °C, protected from light |
| HS Code | 3821.00.00 |
🧪 Incubation Notes
- ✓ Incubate at 46 ± 0.5 °C
- ✓ Read after 18–24 hours
- ✓ Durham tubes recommended for gas detection
- ✓ Anaerobic conditions not required for the described workflow
✅ Method Alignment
- ✓ Used in food microbiology reference workflows
- ✓ Suitable for MPN-based enumeration schemes
- ✓ Applicable for confirmation following selective plating methods
- ✓ Intended for food microbiology use
❄️ Storage & Handling
- ✓ Store prepared tubes at 2–8 °C
- ✓ Protect from light
- ✓ Recommended use within 2 weeks
- ✓ Avoid excessive reheating due to sulfite sensitivity
📄 Available Documentation
Technical Data Sheet (TDS)
Certificate of Analysis (COA)
Safety Data Sheet (SDS)
🧬 Related Clostridium Testing Products
Complementary Media & Workflow Products
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AuSaMicS Pty Ltd • 31 Longview CT, Thomastown, VIC 3074, Australia • ABN 56676640467
Website: www.ausamics.com.au • Email: support@ausamics.com • Phone: +61 412 520 598
For laboratory and food microbiology use only. Product suitability should be verified by the user under validated sample preparation, incubation, confirmation, and regulatory testing conditions.