O-Nitrophenyl-β-D-Galactopyranoside (ONPG) Test

O-Nitrophenyl-β-D-Galactopyranoside (ONPG) Test

Objectives of ONPG Test To determine the ability of an organism to produce β-galactosidase, an enzyme that hydrolyzes the substrate ONPG to form a visible (yellow) product, orthonitrophenol To distinguish late lactose fermenters from non–lactose fermenters of Enterobacteriaceae Principle of ONPG Test The sugar lactose is a disaccharide of galactose and glucose joined by a β-galactoside bond. The ability of bacteria …

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