Application

S-Gal is a patented autoclavable chromogenic substrate for β-galactosidase that is designed to replace X-Gal in blue-white selection of recombinant bacterial colonies with the lac⁺ phenotype.

Suitable for use in selection of recombinant bacterial colonies with the lac+ phenotype. S-Gal^® is autoclavable and can be added to bacterial broth containing agar prior to autoclaving.

Features and Benefits

More intense color contrast than X-gal Excellent for use in automated colony counters Autoclavable for easiest use No need to make stock solutions

When S-Gal is cleaved by β-galactosidase, the resulting product will chelate ferric ion to create a black, insoluble precipitate. Lac⁺ colonies grown in the presence of S-Gal and ferric ion turn an intense black color, allowing for easy differentiation between lac⁺ and lac^- colonies. S-Gal is autoclavable and can be added to your medium of choice prior to autoclaving. S-Gal is not light sensitive and does not require any protection from light sources.

General description

S-Gal^® is an autoclavable, chromogenic substrate for β-galactosidase, used to determine the presence or absence of a cloned DNA insert in bacteria growing on agar plates. S-Gal^® is designed to replace X-Gal in blue-white selection of recombinant bacterial colonies with the lac+ phenotype.

Legal Information

S-GAL is a registered trademark of Sigma-Aldrich Co. LLC

Other Notes

The ferric or Fe³⁺ ion is required for color development and must be added to any S-Gal^®formulation. A medium prepared with S-Gal^® is moderately dark due to the presence of ferric ammonium citrate. This darker background often provides enhanced contrast for automated colony counting or isolation.

Autoclavable, microwavable growth medium complete with S-Gal and IPTG.

Principle

When S-Gal^® is cleaved by ß-galactosidase, the resulting product will chelate ferric ion to create a black, insoluble precipitate. Lac+ colonies grown in the presence of S-Gal^® and ferric ion turn an intense black color, allowing for easy differentiation between lac+ and lac- colonies.

Reconstitution

Stock solutions of S-Gal^® can be made by dissolving 50mg/ml in dimethyl formamide (DMF) and storing at -20C. Add S-Gal^® (300 mg/L from stock solution ) and Ferric Ammonium Citrate (500mg/L) to agar media prior to autoclaving.