In the ONPG and MUG test for fecal coliforms,a sample that is positive for E.coli will be
A)positive for ONPG;fluorescent in UV light.
B)negative for ONPG;fluorescent in UV light.
C)positive for ONPG;non-fluorescent in UV light.
D)negative for ONPG;non-fluorescent in UV light.

Question

Quizplus · Accepted Answer

A sample that is positive for E.coli will produce β-galactosidase enzyme which will result in the hydrolysis of ONPG (ortho-nitrophenyl-β-D-galactopyranoside) and thus produce a yellow color, turning the media to yellow. Also E.coli will produce glucuronidase enzyme which will hydrolyze the MUG (4-methylumbelliferyl-β-D-glucuronide) in the MUG test to produce a fluorescent compound, visible under UV light. Therefore, a positive sample for E.coli would be positive for ONPG and fluorescent in UV light.

In the ONPG and MUG Test for Fecal Coliforms,a Sample