Investigation on enzymic hydrolysis of lignified cellulosic materials

Abstract

Investigations on enzymic hydrolysis of cotton cellulose and spruce groundwood pulp with the multicomponent enzyme Onozuka SS have shown that lignin causes an almost total inhibition of the enzyme action. Breaking of lignified covers of cell walls and fibrillar bundles by grinding increases the accessibility toward the enzyme very effectively. Depolymerization of lignin is less important for improving the accessibility. The compact fibrillar structure of both cotton and wood cellulose also have an inhibitory effect on the penetration of the enzyme into the fiber. Beating loosens the compactness of the fibrillar structure and increases the accessibility. Only about 10% of the cellulose, probably highly crystalline, requires more drastic treatment e.g. ball-milling. Last units of polysaccharides linked to lignin in the lignin carbohydrate complex are resistant toward enzyme hydrolysis and require chemical cleavage. Total enzymic solubilization of lignified polysaccharides can therefore be attained only after a combined mechanical and chemical pretreatment.