Estimation of enzyme activities. Levels of xylanase, cellulase, polygalacturonase and mannanase activities in A. nidulans grown on sorghum for 1, 2, 3, 5, 7 and 14 days. Enzyme activities were measured by the released reducing sugars as measured by the 3, 5-dinitrosalicylic acid (DNS) method and expressed as U/ml. One unit of enzyme activity was defined as the amount of enzyme releasing 1 μmol of product per minute. Data represent mean ± SE.