Single-parameter optimization was carried out for the production of chitinase using a soil isolate belonging to Trichoderma harzianum in solid-state fermentation. Maximum chitinase activity (3.18 U/gds) was obtained after 96 h of incubation at 30degreesC when wheat bran moistened (65.7%) with salt solution was supplemented with colloidal chitin (1%, w/w) and yeast extract (2%, w/w) used as the substrate. The inoculum contains 4 x 10(7) spores of T harzianum (TUBF 781). The growth of the fungus on wheat bran particle was visualized by a scanning electron microscope. Chitinase activity was measured as the amount of N-acetyl glucosamine (NAG) liberated in mumol/min under reaction conditions. The crude extract showed antifungal activity against a wide range of fungal strains belonging to Aspergillus, Rhizopus and Mucor sp., and was found significant against Aspergillus niger (NCIM 563). (C) 2003 Elsevier Ltd. All rights reserved.