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Chapter 6. A procedure was proposed (Fig 6.1) according to which the insoluble residues of pig faeces are submitted to a solution of cellulolytic enzymes. The hydrolysis of the polysaccharides (at 50°C and pH 4.8) proceeds in a relatively short time giving a solution of sugars which can be used for further purposes. A suitable enzyme solution can be obtained by growing T. viride on residues of faeces. The enzyme solution of the spent nutrient solution of the fungus can be easily concentrated by acetone precipitation or by vacuum evaporation. The substrate for the enzymic procedure, the undigested residues of faeces, are adequately degraded when a pretreatment has been applied (grinding to a particle size of 0.08 mm).<br>When the proposed procedure is applied, 150 g of insoluble residues per 1 of enzyme solution can be hydrolysed; 70 % of the residues is converted-into soluble sugars within 4 h. The cellulolytic enzymes are initially adsorbed to the insoluble substrate but are released when hydrolysis proceeds; they can be separated from the undissolved material together with the dissolved sugars. Separation of sugars and enzymes can be achieved by mixing with new substrate which adsorbs the enzymes. After separation of the sugar solution the substrate with enzymes are transferred to the reactor. In this way part of the enzymes can be re-used.<br>In Chapter 6 also the results are given of the purification and separation of a number of enzymes involved in the degradation of the cellulose-, hemicellulose-, lignin complex (Fig. 6.8). The mixture of enzymes, excreted by T. viride when the organism was growing on undigested plant residues of pig faeces, was separated into several protein fractions each with its own enzyme activity with respect to different substrates, i.c. endoglucanase, exoglucanase and hemicellulase activity (Figs. 6.9-6.12).<br>Degradation of undigested components of pig faeces in view of recycling of the faeces is no simple procedure. Microbial (enzymic) break-down is possible if a suitable pretreatment is applied. The economical applicability of the results obtained in this investigation will depend on: (a) the occurrence of excessive amounts of manure, (b) disposal problems, particularly in connection with the environment, (c) alternative methods for processing excessive amounts of manure.