Ultrasonically assisted single stage and multiple extraction of enzymes produced by Aspergillus oryzae on a lignocellulosic substrate with solid-state fermentation

The efficient extraction of enzymes from the fermented matter of solid-state fermentation is a key consideration in producing enzymes in a cost effective way. In this research low frequency ultrasound at different amplitudes was used to intensify the single stage and multiple (three-stage) extractions of ligninolytic and hydrolytic enzymes from a cultivated solid produced with Aspergillus oryzae NRRL 3485, using flax fiber as a support and actual lignocellulosic substrate. Kinetics of buffer extraction at pH 5 and 50 degrees C was followed within a period of 60 min by measuring the enzyme activities. Results proved that sonication has an enormous effect on the enzyme extraction. The maximum enzyme activities obtained in a conventional single stage extraction could be increased with sonication by 111.4%, 167.9% and 93.8% for filter paper, polygalacturonase and lignin peroxidase activities, respectively. Results also revealed that sonication (at 40, 60 and 80% amplitudes, for 60 min) did not result in a reduction in the filter paper and polygalacturonase activities of the crude enzyme solution, but slightly decreased the lignin peroxidase activity by about 20% at the highest amplitude. Three-stage extraction with sonication at 60% amplitude provided about 2.1-2.7 times higher enzyme yield. (C) 2015 Elsevier Ltd. All rights reserved.