Phanerochaete chrysosporium JAG-40 was isolated from the soil samples saturated with spilled molasses collected from a sugar mill. This isolate decolourised synthetic and natural melanoidins present in spentwash in liquid fermentation; up to 80% in 6 days at 30 degreesC under aerobic conditions. A large inoculum size stimulated fungal biomass production, but this gave less decolourisation of pigment; 5% w/v (dry weight) mycelial suspension was found optimum for maximum decolourisation in melanoidin medium supplemented with glucose and peptone. Gel-filtration chromatography showed that larger molecular weight fractions of melanoidin were decolourised more rapidly than small molecular weight fractions. (C) 2001 Elsevier Science Ltd. All rights reserved.