266Ligninolytic potential of white rot fungus Stereum ostrea on solid support polyurethane cubes (6 and 8 cubes) in liquid Koroljova medium under the influence of chlorpyrifos at 20 ppm concentration for 10 days was assessed in the present study. The growth and secretion of extracellular proteins by S. ostrea only on 8 sponge cubes were comparable with that of Stereum ostrea in the free state. Secretion of laccase by immobilized (8 cubes) and the free culture of S. ostrea occurred to the same extant of 42 U/ml on the 8th day of incubation. However, the yields of ligninolytic enzymes - laccase (LAC), manganese peroxidase (MnP), and lignin peroxidase (LiP) by immobilized culture with 8 cubes were higher than the titre of the respective enzymes by Stereum ostrea in the free state on the 10th day of incubation. The yields of laccase, MnP, and LiP by 8 cubes of immobilized culture were 62, 18.5, and 0.47 U/ml as against 15.0, 4.75, and 0.195 U/ml by S. ostrea in the free state. Reusability of immobilized culture for different applications has been discussed in the present study.