The cellulases of Trichoderma viride : mode of action and application in biomass conversion

Beet pulp and potato fibre were liquefied and saccharified with a combination of cellulase from Trichodermaviride and pectinase from Aspergillusniger . Cell wall polysaccharides were hydrolysed extensively. The application of a packed column reactor, connected with a hollow fibre ultrafiltration unit was investigated for the enzymatic hydrolysis of beet pulp. A high degree of polysaccharide hydrolysis of spent grain by the action of cellulases was obtained after pretreatment with sulfuric acid or sodium hydroxyde. Essentially only monomeric sugars were present in the enzyme digest of the acid pretreated material . Six endoglucanases, three exoglucanases and a β-glucosidase were purified from a commercial cellulase preparation of T . viride origin. These enzymes were characterized with respect to their activities on several cellulosic substrates as well as chemical and physical properties. The β-glucosidase showed no cellobiase activity . Random and less random acting endoglucanases were distinguished. Adsorption, kinetic and synergistic behaviours of these enzymes were investigated on crystalline cellulose. It was shown that an optimal ratio of endoglucanase to exoglucanase was needed in order to obtain a maximal degree of synergism. This ratio could be related to the adsorption behaviours of the cellulases, suggesting that synergism between endoglucanases and exoglucanases takes place in very close cooperation at the surface of the cellulose particle . From activity experiments on xylan specific and nonspecific glucanases could be demonstrated. However, the non-specific glucanases prefer to hydrolyse β-1,4-glucosidic linkages over β-1,4-xylosidic bonds.