p-Nitrophenyl galacto-N-bioside has been used as a substrate to assay the activity of ?-galactosidase (AnGAL), rhamnogalacturonan acetylesterase (AnRAE), and ?-L-arabinofuranosidasae (AnAF). It has also been used as a disaccharide model substrate to assay endo-GalNAc-ase S activity in the culture broths.