Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
The aim of the present study was to investigate a new approach to β-glucosidase production of an Aspergillus strain using cheap lignocellulosic material i.e. waste paper in order to substitute glucose, a generally used carbon source, and thereby reduce the production cost. The enzyme production was performed and optimized for the highest β-glucosidase yield in cofermentation with a Trichoderma strain to support the degradation of cellulose and to provide the non-cellulolytic Aspergillus with water soluble carbon source. Batch fermentation experiments of Aspergillus niger BKMF 1305 and Trichoderma reesei RUT C30 were carried out in shake flask cultures. The factors influencing the enzyme production, such as the concentrations of nutrients and carbon source, the inoculum ratio of the two species, and the delay in A. niger inoculation were investigated using a 23 full factorial design. The results were analyzed with the response surface methodology using commercially available software, Statistica for Windows. All three examined factors were found significant. The highest β-glucosidase activity of 3.07 IU/mL was obtained after 7 days of incubation, if 3.3 % Aspergillus and 6.7 % Trichoderma inoculum were added at the same time to modified Mandels’ medium, in which the concentration of nutrients was doubled compared to normal Mandels’ medium and the carbon source concentration was set to 20 g/L waste paper
