Liofilchem® Bryant and Burkey Medium

Liofilchem® Bryant and Burkey Medium is a selective and differential culture medium used for the enumeration of lactate-fermenting spore-forming anaerobes, particularly Clostridium species, in milk and dairy products.

Formulated according to Bryant and Burkey (1956), this medium supports the growth of Clostridium perfringens and Clostridium tyrobutyricum while inhibiting non-spore-forming or non-lactate-fermenting organisms. It is primarily applied in dairy microbiology to detect clostridial spores responsible for late blowing defects in cheese and other spoilage phenomena.

Key Features

• Selective for spore-forming anaerobes such as Clostridium spp.
• Differential by gas formation and medium displacement (paraffin layer movement).
• Optimized for dairy testing—detects lactate-fermenting clostridia in milk and cheese.
• Supports spore germination through sodium acetate enrichment.
• High recovery and reproducibility validated for routine quality control.
• Shelf life of 4 years with consistent media performance.

Typical Formula (per litre)

Principle of the Method

• Tryptone, meat extract, and L-cysteine provide essential amino acids, peptides, and cofactors for clostridial growth.
• Yeast extract contributes B-complex vitamins to stimulate bacterial metabolism.
• Sodium acetate promotes selective germination of spores and acts as a growth modulator.
• Calcium lactate supplies fermentable lactate for Clostridium energy metabolism.
• Resazurin serves as a redox indicator for anaerobiosis.
• Paraffin overlay maintains anaerobic conditions and indicates gas production through visible displacement.

Preparation

1. Suspend 38 g of the dehydrated medium in 1 L of distilled or deionized water.
2. Heat until completely dissolved.
3. Dispense 10 mL aliquots into tubes.
4. Autoclave at 121°C for 15 minutes.

Test Procedure

1. Prepare tenfold dilutions of the sample in sterile diluent.
2. Inoculate 1 mL of each dilution into triplicate tubes of Bryant and Burkey Medium.
3. Overlay each tube with ~2 mL of sterilized paraffin (60–65°C).
4. Heat at 75°C to kill vegetative cells and activate spores.
5. Incubate at 35°C for up to 6 days.
6. Observe daily for turbidity and gas production.

Interpretation of Results

Enumeration is determined using the Most Probable Number (MPN) method.

Quality Control

Appearance (Dehydrated): free-flowing, tan homogeneous powder

Appearance (Prepared): clear, light amber to reddish

Storage and Stability

• Store dehydrated medium at 10–30°C in a dry, tightly closed container.
• Store prepared tubes at 2–8°C.
• Shelf life: 4 years under recommended storage conditions.

Safety and Handling

• Not classified as hazardous under current regulations.
• For professional laboratory use only by trained personnel.
• Refer to the Safety Data Sheet (SDS) before use.
• Dispose of biological materials according to national and local regulations.

Ordering Information

Conclusion

Liofilchem® Bryant and Burkey Medium offers a reliable, standardized formulation for the enumeration of lactate-fermenting spore-forming anaerobes, particularly Clostridium species, in dairy and related samples. Its nutrient-rich base, controlled selectivity, and clear anaerobic growth indicators make it an essential medium for dairy microbiology laboratories, ensuring accurate detection of spoilage and hygiene-related contamination.