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B9146 Sigma-Aldrich

5-Bromo-4-chloro-3-indolyl β-D-galactopyranoside


Synonym: 5-Bromo-4-chloro-3-indolyl β-D-galactoside, BCIG, X-Gal

  • CAS Number 7240-90-6

  • Empirical Formula (Hill Notation) C14H15BrClNO6

  • Molecular Weight 408.63

  •  Beilstein Registry Number 1402009

  •  EC Number 230-640-8

  •  MDL number MFCD00005666

  •  PubChem Substance ID 57653968



Related Categories Chromogenic, Galactoside, Gene Reporter Substrates, Glycobiology, Inhibitors and Substrates,
assay   ≥98%
suitability   suitable for identification of lac+ bacterial colonies
storage temp.   −20°C



X-Gal is a chromogenic substrate for β-galactosidase that produces a rich blue color that can easily be detected visually over background. X-Gal is the substrate of choice for blue-white selection of recombinant bacterial colonies with the lac+ genotype.


10, 100, 500 mg in poly bottle


A stock solution (100 mg/ml) is prepared by dissolving X-Gal in dimethylformamide and should be stored at −20 °C and protected from light. Sterilization is not required.

Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 
Protocols & Articles


Competent Cell Protocols

Transformation is a process by which some bacteria take up foreign genetic material (naked DNA) from the environment. Once it enters the cytoplasm, the genetic material may be degraded by nucleases i...
Keywords: Antibiotics, Cloning, Detergents, Electrophoresis, Gel electrophoresis, Gene expression, Genetic, Molecular biology, Peptide synthesis, transformation

Introduction to Blue-White Screening

Blue-white screening is a rapid and efficient technique for the identification of recombinant bacteria. It relies on the activity of β-galactosidase, an enzyme occurring in E. coli, which cleaves lac...
Keywords: Antibiotics, Cloning, Culture media, Gene expression, Immunocytochemistry, Peptide synthesis, Polymerase chain reaction, Recombination, Sterilizations, transformation

Recombinant Protein Expression in Saccharomyces cerevisiae

Expressing recombinant proteins in yeast has many advantages, simple protocols, use of basic reagents, appropriate processing of eukaryotic proteins, and scalability. We are an essential part of your...
Keywords: Cell disruption, Gene expression, transformation


Introduction to Yeast Transformation

Transformation is the process by which exogenous DNA is introduced into a cell, resulting in an inheritable change or genetic modification. This was first reported in Streptococcus pneumoniae by Grif...
Keywords: Cell disruption, Food & Beverage, Gene expression, Genetic, Molecular biology, Pharmaceutical, Polymerase chain reaction, transformation

Microbial Growth Protocols

From our library of Protocols, Sigma-Aldrich presents Microbial Growth Protocols
Keywords: Antibiotics

Transformation Protocols

From our library of Protocols, Sigma-Aldrich presents Transformation Protocols
Keywords: Antibiotics, Detergents, Electrophoresis, Gel electrophoresis, Mass spectrometry, Peptide synthesis, transformation

Yeast Transformation Protocols

Yeasts are considered model systems for eukaryotic studies as they exhibit fast growth and have dispersed cells. Moreover, replica plating and mutant isolation of yeast cells can be done with relativ...
Keywords: Degradations, Genetic, Molecular biology, Transfection, transformation

Peer-Reviewed Papers


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