Pectin lyase (Pl) and polygalacturonase (Pg) production by Thermoascus aurantiacus 179-5 was carried out by means of solid-state fermentation using orange bagasse, sugar cane bagasse and wheat bran as a carbon sources. Pg and PI had optimum activity at pH 5.0 and 10.5-11.0, respectively. Maximal activity of the enzymes were determined at 65 degreesC. Pg was stable in the acidic to neutral pH range and at 60 degreesC for 1 h. whereas Pl was stable at acidic pH and at 60 degreesC for 5 h. (C) 2002 Elsevier Science Ltd. All rights reserved.