How do the ONPG and MUG test detect microorganisms in water
A)color is changed by enzymes secreted by coliform bacteria
B)gas production in cultures of lactose broth
C)observing dark colonies of coliform organisms on EMB-lactose agar
D)colonies forming on surface of a sterile absorbent pad

Question

Quizplus · Accepted Answer

ONPG (O-Nitrophenyl-beta-D-galactopyranoside) and MUG (4-Methylumbelliferyl-beta-D-glucuronide) are both substrates that are hydrolyzed by the enzyme beta-galactosidase, which is found in coliform bacteria. The hydrolysis of ONPG and MUG results in a color change or fluorescence, respectively, indicating the presence of coliform bacteria in the water sample. Therefore, choice A is the best answer as the color change is due to the enzymes secreted by coliform bacteria.

How Do the ONPG and MUG Test Detect Microorganisms in Water