Presence Absence (P-A) test with MUG (4-Methylumbelliferyl-β-D-glucuronide):

The P-A test is frequently used for routine examination of drinking water. Coliform analysis by the P-A test is based on 2 premises: 1) no coliform bacteria should be present in 100 mL of drinking water, and 2) if one viable cell is present it will multiply to give a population of cells that will ferment lactose to produce acid and gas. Thus, P-A broth contains lactose and a pH indicator, which will change from purple to yellow if lactose is fermented and acid is produced. To this P-A broth, the compound 4-Methylumbelliferyl-β-D-glucuronide (MUG) has been added. This initially colorless compound can be hydrolyzed by the E. coli β-glucuronidase enzyme to form a compound (4-methylumbeliferone) that fluoresces under long UV light (336 nm). Observing for fluorescence emission is a sensitive way to confirm the presence of E. coli in water samples.

Rachel Watson, M.S.
AG 5010
766-3524
Cell: 307-760-2942
rwatson@uwyo.edu