Indicator compounds

From ActinoBase

Indicator Compounds

Indicator compounds can be used to measure the activity of enzymes such as β-galactosidase or β-glucuronidase. These compounds are usually added directly to the bacterial growth medium and provide a qualitative measure of enzyme activity via a colorimetric change. (For example, the colourless compound 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal) is converted into a dark blue product by a β-galactosidase; similarly, colourless 5-Bromo-4-chloro-1H-indol-3-yl β-D-glucopyranosiduronic acid (X-Gluc) (X-gal) is converted into a dark blue product by a β-glucuronidase.)

These compounds can be used to measure native enzyme activity, but are perhaps most commonly used with reporter genes, where the promoter or gene of interest is fused to the gene encoding the enzyme (i.e. β-galactosidase or β-glucuronidase).

A number of different reporter systems have been tried in Streptomyces: the most commonly used is perhaps the β-glucuronidase Gus.[1]

5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal)


Instructions for use

5-Bromo-4-chloro-1H-indol-3-yl β-D-glucopyranosiduronic acid (X-Gluc)


  • Detection of β-glucuronidase activity on solid media
  • Screening for β-glucuronidase -positive or -negative candidates[1]

Instructions for use

  1. C



[1] Myronovskyi, M., Welle, E., Fedorenko, V., & Luzhetskyy, A. (2011). Beta-glucuronidase as a sensitive and versatile reporter in actinomycetes. Applied and environmental microbiology, 77(15), 5370–5383.