DIAGNOSTIC DISCS 50 discs Code: DD 507
for the rapid detection of ß-galactosidase activity
Purpose and usage:
ONPG diagnostic discs are designed for the detection of ß-galactosidase. This test serves for the differentiation for e.g. Neisseria lactamica from other Neisseriae.
The test is based on the detection of ß-galactosidase which hydrolyses o-nitrophenyl-ß-galactopyranoside.Colored O-nitrophenol develops during this reaction.
Prepare a dense suspension (degree No.3 of McFarland turbidity scale) from the examined strain in a test tube with 0.4 ml sterile distilled water.Put ONPG disc into the test tube with the suspension and incubate for 3 hours at 37°C. Incubate test tubes with no color changes overnight at room temperature as some strains have delayed positive reaction.
The suspension with the submerged disc becomes yellow if the reaction is positive (ONPG +). No change of color appears if the reaction is negative (ONPG -).
1. ONPG discs are designed for laboratory use only.
2. Discs should be stored in a dark place at +4°C and should not be used beyond the expiration date shown on the packing.