INTENDED USE
- BacterTest™ α-Naphthol is a reagent commonly used in chemical and analytical reactions to detect, identify, or quantify certain substances or ions in a sample. In the Voges-Proskauer method, α-Naphthol is one of the two main reagents (along with KOH), and its role is to aid in detecting the presence of acetoin in the culture medium.
PRINCIPLES
- BacterTest™ α-Naphthol is one of the two main reagents in this test, with an important role in the detection of acetoin.
- Acetoin (or 3-hydroxybutanone) is produced during the fermentation of glucose (or other carbohydrates) by some species of bacteria.
- When the culture medium contains acetoin, the α-Naphthol reagent will react with acetoin, forming a red or pink complex.
- KOH is necessary to increase the alkalinity of the medium, helping acetoin to convert into substances that can react with α-Naphthol, creating a recognizable color.
- Bacteria are cultured in prepared MR-VP medium after 24 – 48 hours at 37°C (to allow bacteria time to ferment glucose in the medium)
- Adding 0,5 mL of 40% KOH solution to the sample.
- Then, adding 3 – 4 drops of α-Naphthol reagent to the cultured bacteria sample.
- Reacting within minutes to hours.
- Observing the color change of the medium, reading and recording the results
RESULTS
- Observe the color change of the environment:
- Red or pink = Positive (Bacteria that produce acetoin)
- Colorless or Yellow = Negative (Bacteria do not produce acetoin).
BacterLab ensures the quality of each product batch by testing with ATCC reference strains.
| Reference strains | Growth | α-Naphthol + KOH |
| E. coli ATCC 35218 | Good growth | (–): Colorless or Yellow |
| E. cloacae ATCC 13047 | Good growth | (+): Red or pink |
Refer to the components.
| α-Naphthol | 5,0 g |
| Ethanol (95%) | 100mL |
*Note: This ingredient is for reference only our company will formulate the ingredient according to requests or tender specifications.
| Product Name | Code | Packaging |
| BacterStrain™ α-Naphthol | 06005 | 100mL/ dropper bottle or as per customer request. |
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