An elicitor of plant disease resistance, pectinase, was produced by solid state fermentation with Aspergillus niger. Sugar beet pulp was used as carbon source and the wastewater from monosodium glutamate production was used as nitrogen and water source. The composition of the fermentation medium was: 11 ml concentrated wastewater (containing NH3-N 38.2 mg/ml), sugar beet pulp 10 g, Na2HPO4 (.) 12H(2)O 0.2 g KH2PO4 0.04 g in a 500 ml Erlenmeyer flask. The fermentation temperature was 30 degreesC and the relative humidity of the air was 75-90%. The maximum production of pectinase was reached after 96 It cultivation. The crude pectinase extracted from the fermented materials could elicit disease resistance in cucumber and tomato seedlings. (C) 2004 Elsevier Ltd. All rights reserved.