Esculinase (beta-glucosidase) for the rapid estimation of activity in bacteria utilizing a hydrolyzable substrate, p-nitrophenyl-beta-D-glucopyranoside.

The ability of bacteria to hydrolyse esculin is an important phenotypic characteristic for their identification. The presence of 'esculinase' is especially useful in identifying genera of the Enterobacteriaceae and in separating Bacteroides, Listeria, and group D streptococci from other pathogens. Three methods have been used to measure esculin hydrolysis. Each of these methods suffered from limitations. A new procedure employing the hydrolysable substrate p-nitrophenyl-beta-D-glucopyranoside was developed. This method required only 15 min incubation at either room temperature or 35 degrees C, may be used either qualitatively or quantitatively, and is inexpensive. The sensitivity and specificity of this method was found to be equivalent to that of the standard methodology.