Extracellular L-glutaminase production by Beauveria sp., isolated from marine sediment, was observed during solid state fermentation using polystyrene as an inert support. Maximal enzyme production (49.89 U/ml) occurred at pH 9.0, 27 degrees C, in a seawater based medium supplemented with L-glutamine (0.25% w/v) as substrate and D-glucose (0.5% w/v) as additional carbon source, after 96 h of incubation. Enzyme production was growth associated. Results indicate scope for production of salt tolerant L-glutaminase using this marine fungus. (C) 2000 Elsevier Science Ltd. All rights reserved.