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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/REAXYS 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



10, 100, 500 mg in poly bottle


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.


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 


Certificate of Analysis


Certificate of Origin

Protocols & Articles


Blue-White Screening & Protocols for Colony Selection

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, Molecular biology, Peptide synthesis, Polymerase chain reaction, Recombination, Sterilizations, transformation

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

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


Bacterial Transformation Protocols

Transformation is a key process in molecular cloning, by which multiple copies of recombinant DNA molecules are produced. The ability to take up free, extracellular genetic material is the prerequisi...
Keywords: Antibiotics, Cloning, Detergents, Electrophoresis, Gel electrophoresis, Genetic, Mass spectrometry, Peptide synthesis, transformation

Introduction to Yeast Transformation

Yeasts are eukaryotic model systems for studies as they exhibit fast growth and have dispersed cells. They have a well-defined genetic system and a highly versatile DNA transformation system that can...
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

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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