I have used Arbutin (modified) and esculin for screening purpose. The strains never showed presence of β-glucosidase activity, responded very fast on esculin. Not clear why these strains become positive on esculin??????????
By using p-nitrophenyl-beta gluside or other substate e.g 4-methylumbelliferyl-b-D-glucopyranoside. and following the coloured cleavage products by spectrophotometer. For example see Rosi et al 2005
Thanks Enrico. Gone through the results of suggested paper. Almost all strains were found positive in case of MUG while the medium Asculin 5 g/L showed minimum strains for response. Then which test is better?
All strains are positive or few are positive??????????
Then it is better to go for confirmation by estimation of activity.