Glucose oxidase activity in soil and its possible interference in assays of cellulase activity

The occurrence of naturally-occurring glucose oxidase activity in a soil collected at a depth of 0–8 cm under tussock has been indicated. This activity was probably responsible for utilization of some of the glucose added to a system of soil, buffer and toluene that was incubated at 30°C; no loss of added glucose was apparent at 50°C.The cellulase activity of this soil was assessed by measuring rates of hydrolysis of added cellulose with Somogyi and anthrone reagents in systems of soil, buffer and toluene at 30 and 50°C. The production of reducing sugars was approximately linear over the first 48 or 72 h of incubation but appeared to decline subsequently at both temperatures. Interference by the activity of the naturally-occurring glucose oxidase at 30°C is suggested. Interference by glucose oxidase appears less likely at 50°C because of the apparent stability of added glucose at this temperature and the instability of added glucose oxidase. An incubation period of 48 h at 30°C appears generally satisfactory for assaying the cellulase activity of this soil.The possible role of glucose oxidase in interfering in assays of other soil enzymes in which the production of glucose is measured is discussed.