3.2. Multi-enzyme production by solid-state fermentation
A mixture of different degradative enzymes, or multi-enzyme,was obtained by solid-state fermentation of agricultural residues as the major carbon and nitrogen sources with supplements of nutrients and trace minerals. A 3.5:1.5 ration of dried cassava pulp:soybean meal was found to be an optimal ratio of major substrates for fermentative growth of the fungus. In total, 13.5 L of the crude multienzyme was extracted from 20 kg of solid-state culture. Com-parable enzyme activities were obtained when enzyme production was scaled up to the tray reactor system from small scale flask production (data not shown). The crude multi-enzyme was a complex mixture of plant cell wall degrading enzymes containing endo-acting cellulase, pectinase, -glucanase, and hemicellulases as the major activities together with various exo-acting glycosyl hydro-lases which acted cooperatively with the endo-acting enzymes(Table 2). The protein concentration of the crude extract was 4.48 mg/mL. The crude enzyme was then clarified and concentrated 15 folds by ultrafiltration. The concentrated enzyme was then used for viscosity reduction study.