BacterTest™ KOH

This reagent and α-Naphthol reagent are used in MR-VP culture medium to perform VP test.
Code: 06004
Packaging: 100mL/ dropper bottle or as per customer request.
Storage Conditions: 8 – 25°C.
Transportation: Ambient temperature.
Shelf Life: 12 months from the date of manufacture.

INTENDED USE

BacterTest™ KOH is one of the two main reagents (along with KOH) in the Voges-Proskauer method, playing an important role in creating the alkaline environment necessary for acetoin (or 3-hydroxybutanone) in the sample to react with α-Naphthol, forming a red or pink complex.

PRINCIPLES

BacterTest™ KOH 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	CULTURE CONDITIONS	Α-NAPHTHOL + KOH
Culture conditions: 18 – 24 hours, incubated at 35 – 37°C_, inoculum ≤ 10² CFU/mL
K. pneumonia NCTC 13442	Good growth	(–): Red
E. coli ATCC 35218	Good growth	(+): Yellow or no change