Sigma-Aldrich Kovacs Indole Reagent For

Quality Level

200

Form

liquid

Packaging

pkg of 100 mL

Storage Condition

(No metal containers. Keep the container tightly closed in a dry and well-ventilated place. Keep away from heat and sources of ignition)

Technique(S)

microbe ID | specific enzyme detection: suitable

Color

yellow

pH

<1 (20 °C in H₂O)

Transition Temp

flash point 36 °C

Density

0.92 g/cm³at 20 °C

Application(S)

microbiology

Related Categories

Microbial Identification Tests

General Description

Kovac′s reagent is a biochemical reagent composed of n-Butanol, hydrochloric acid, and 4-dimethylaminobenzaldehyde. It is used for the detection of indole producing microorganisms. Tryptophan is abundant in trypticalle digested peptone. Some microorganisms can cleave tryptophan to give pyruvic acid, ammonia, and indole. Indole then reacts with 4-dimethylaminobenzaldehyde to form a dark red dye. As tryptophan also gives a color reaction with 4 dimethylaminobenzaldehyde, it must be separated from the indole. This is achieved by selectively extracting indole with butanol.

Application

Kovac′s Indole reagent is used for the detection of indole producing microorganisms in food and beverages, and environmental samples. This is suitable for the identification ofE. coli.

Analysis Note

Indole formation (Escherichia coli ATCC 25922 (WDCM 00013)): +
Indole formation (Proteus vulgaris ATCC 8427): +
Indole formation (Enterobacter aerogenes ATCC 13048): -
Tested in DEV-Tryptophan broth art. no. 1.10694. (after incubation 24 hrs.; 35 °C aerobic).

Other Notes

The reagent solution must be stored in the dark in the refrigerator, otherwise it may turn brown and cannot be used.

Pictograms

GHS02,GHS05,GHS07

Signalword

Danger

Hcodes

H226 - H290 - H302 - H314 - H317 - H335 - H336

Pcodes

P210 - P233 - P280 - P301 + P312 - P303 + P361 + P353 - P305 + P351 + P338

Hazard Classifications

Acute Tox. 4 Oral - Eye Dam. 1 - Flam. Liq. 3 - Met. Corr. 1 - Skin Corr. 1 - Skin Sens. 1

Storage Class

3 - Flammable liquids

Wgk_Germany

WGK 1

Flash_Point_F

96.8 °F

Flash_Point_C

36 °C