A pratical method for screening for (beta)-galactosidase secreting microbial colonies

Microbial colonies were replicated on YNB© agar plates overlaid with soft agar containing the glucose-oxidase/peroxidase (BIOTROLr) system. The pink color developed around the colonies was the result of the reaction of this enzyme. This method proved to be very convenient for testing hundreds of colonies grown on agar plates for (beta)-galactosidase secretion by microbial cells.