An externally unskinned polysulfone ultrafiltration capillary membrane was used as an immobilisation matrix for the white rot basidiomycete Phanerochaete chrysosporium ME446. In this study, different membrane bioreactor configurations, scanning electron microscopy, atomic force microscopy and enzyme assays were used to characterise the spatial distribution of spores after immobilisation by reverse filtration and document the subsequent growth phases. A single capillary membrane bioreactor was also used to develop and evaluate a spore immobilisation technique by modifying conventional bioreactor configurations for reverse filtration onto the external surface of the membrane. Results indicate that spore immobilisation was dependent on a differential pressure across the tube wall and the fluid flow pattern in the tube, thus influencing the spatial distribution of spores along the surface and within the microvoids in the membrane wall. The resultant radial and lateral biofilm development using this reverse filtration approach promoted uniform biomass development, which favoured manganese peroxidase production. (C) 2004 Elsevier B.V. All rights reserved.