The combined effect of depressed water activity (a(w)) and glucose addition on the production of extracellular pectinases and protease by Aspergillus niger 148 was studied. A differential response in the production of enzyme activities was observed. Glucose (0.7%) acted as catabolite repressor for all the enzymes at a(w) = 1 and at a(w) = 0.975 for pectinesterase, pectinlyase and protease. For polygalacturonase at a(w) = 0.975 a synergistic stimulating effect was observed. By depressing a(w) a pectinase complex containing mainly pectinlyase and polyglalacturonase could be obtained.