A SENSITIVE METHOD USING 4-METHYLUMBELLIFERYL-BETA-CELLOBIOSE AS A SUBSTRATE TO MEASURE (1,4)-BETA-GLUCANASE ACTIVITY IN SEDIMENTS

A sensitive method to measure (1,4)-beta-glucanase activity in organic matter-rich sediments, using 4-methylumbelliferyl-beta-cellobiose as a substrate, is described. beta-Glucosidases, which were also able to hydrolyze this substrate, were inhibited with D-glucono-delta-lactone. The produced 4-methylumbelliferone was recovered quantitatively out of the sediment by an extraction with 80% ethanol. An inhibition experiment with known substrates or inhibitors suggested that at least 59% of the measured activity could be explained by enzymes of the exo-(1,4)-beta-glucanase type and that the contribution of endo-(1,4)-beta-glucanases was minor. Results of the inhibition experiment also suggested that the measured activity was of bacterial origin in the sediment used. First results of field measurements are given for the sediment from the reed bed of Lake Gooimeer.