Pinnacle™ TBGA/TBX (Tryptone Bile Glucuronide Agar)

Product Code: PIN002

A pre-prepared agar based on Lab M’s established Harlequin™ TBGA/TBX, product reference HAL003.

Tryptone Bile Glucuronide Agar is recommended by ISO 16649 for enumeration of β-glucuronidase-positive Escherichia coli in products intended for human consumption or for the feeding of animals. The medium contains tryptone as a source of nitrogen and amino acids, bile salts act as a selective against Gram-positive organisms and agar is the gelling agent. 5-bromo-4-chloro-3-indolyl-β-D-glucuronide (X-glucuronide) is a chromogen for the detection of the β-D-glucuronidase enzyme which is present in most E.coli* but not other coliforms. The intracellular enzyme present in E.coli is able to break the bond between the substrate and the chromophore which dimerises is the presence of oxygen to form an insoluble coloured compound within the cell. The accumulation of the coloured chromophore results in blue colonies on the agar. This medium conforms to the performance requirements of ISO 11133:2014.

*96-97% of E.coli are β-D-glucuronidase positive. A notable exception is E.coli O157:H7

Related Sector(s)

• Dairy
• Food

Related Organism(s)

• E.coli