Production and extraction of pectinases obtained by solid state fermentation of agroindustrial residues with Aspergillus niger

In this work soy and wheat bran were employed as raw materials for the production of pectinases by Aspergillus niger through solid-state fermentation. Several fermentation and recovery parameters were studied. The kinetics of enzyme synthesis was investigated in the range from 13 to 96 h with moisture contents varying from 25% to 70% (w/w). A medium moisture content of 40% and a fermentation time of 22 h were selected, as these conditions resulted in high pectolytic activity and enhanced polygalacturonase productivity. In order to optimise the recovery step, the best combination of temperature of extraction, contact time and solvent type was investigated. Acetate buffer (pH 4.4), 35 degrees C and 30 min provided the best recovery. The present results !;how that optimising the extraction conditions is a simple way of obtaining more concentrated enzyme extracts and could be a useful instrument to extract more selectively a desired biomolecule from fermented solids. (C) 1999 Elsevier Science Ltd. All rights reserved.