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Liofilchem™ Ornithine Decarboxylase Broth, 500 g
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Specifications:
| Application | Microbiology | ||
| Storage Temperature | Ambient | ||
| Product Type | Culture Medium | Forms | Powder |
| Product Brand | Liofilchem | ||
| Product Grade | Microbiology grade | ||
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)
| Component | Concentration (g/L) |
|---|---|
| Peptone | 5.0 |
| Meat Extract | 5.0 |
| Pyridoxal | 0.005 |
| Dextrose | 0.5 |
| L-Ornithine | 10.0 |
| Bromocresol Purple | 0.010 |
| Cresol Red | 0.005 |
| Final pH | 6.0 ± 0.2 |
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
- Suspend 21.0 g of powder in 1 L of distilled water.
- Heat until fully dissolved.
- Dispense into tubes or flasks.
- Autoclave at 121°C for 15 minutes.
Test Procedure
- Inoculate with 1–2 colonies from a fresh culture.
- Mix thoroughly.
- Overlay with 1 mL of sterile vaseline oil.
- Incubate at 36 ± 1°C for up to 96 hours.
- Observe for color changes from 24 to 96 hours.
Interpretation of Results
| Medium Color | Result | Interpretation |
|---|---|---|
| Purple | Positive | Ornithine decarboxylase activity (+) |
| Yellow | Negative | No ornithine decarboxylase activity |
Quality Control Strains
| Microorganism | Color | Result |
|---|---|---|
| Escherichia coli ATCC 25922 | Purple | + |
| Salmonella typhimurium ATCC 14028 | Purple | + |
| Klebsiella pneumoniae ATCC 13883 | Yellow | – |
| Pseudomonas aeruginosa ATCC 27853 | Purple | + |
| Enterobacter aerogenes ATCC 13048 | Purple | + |
| Proteus mirabilis ATCC 25933 | Purple | + |
Product Specifications
| Property | Details |
|---|---|
| Product Name | Ornithine Decarboxylase Broth |
| Code | 610305 (500 g) |
| Medium Form | Dehydrated powder |
| Appearance (Dehydrated) | Beige, free-flowing |
| Appearance (Prepared) | Clear, purple |
| pH (Final Medium) | 6.0 ± 0.2 |
| Shelf Life | 4 years |
| Storage (Powder) | 10–30°C, dry, sealed |
| Storage (Prepared Media) | 2–8°C |
| Packaging | Plastic bottles |
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.