Liofilchem™ Ornithine Decarboxylase Broth, 500 g

For Differentiation of Gram-Negative Enteric Bacilli via Ornithine Decarboxylation

Ornithine Decarboxylase Broth is a dehydrated culture medium used for the biochemical differentiation of gram-negative enteric bacilli based on their ability to decarboxylate L-ornithine into putrescine. This reaction is catalyzed by the enzyme ornithine decarboxylase and results in a pH shift that is detected by color change in the medium.

Typical Composition (per Liter)

Principle of the Test

• Peptone and meat extract provide nitrogen and essential growth factors.
• Dextrose fermentation by enteric bacteria initially lowers the pH, turning the medium yellow.
• Pyridoxal acts as a cofactor for the enzyme.
• If the organism produces ornithine decarboxylase, ornithine is converted to putrescine, raising the pH and turning the medium back to purple.
• The pH change is visualized using bromocresol purple and cresol red indicators.

Preparation Instructions

1. Suspend 21.0 g of powder in 1 L of distilled water.
2. Heat until fully dissolved.
3. Dispense into tubes or flasks.
4. Autoclave at 121°C for 15 minutes.

Test Procedure

1. Inoculate with 1–2 colonies from a fresh culture.
2. Mix thoroughly.
3. Overlay with 1 mL of sterile vaseline oil.
4. Incubate at 36 ± 1°C for up to 96 hours.
5. Observe for color changes from 24 to 96 hours.

Interpretation of Results

Quality Control Strains

Product Specifications

Safety & Disposal

• Not classified as hazardous.
• For in vitro diagnostic use only.
• Use by trained laboratory personnel.
• Dispose of according to local and national regulations.

The Liofilchem® Ornithine Decarboxylase Broth is a reliable and validated medium for the detection of ornithine decarboxylase activity in gram-negative bacteria. It is widely applicable in clinical, food, environmental, and pharmaceutical microbiology and plays a critical role in biochemical bacterial differentiation.