Comparison of cell-walls of Lolium multiflorum with cotton cellulose in relation to their digestion with enzymes associated with cellulolysis

Abstract

Activities of several enzymes associated with cellulolysis were compared using as substrates cell-walls of Lolium multiflorum and cotton cellulose. Purified enzymes C 1 (see Ref. 1 for definition), C. x (CM-cellulase) and β-glucosidase were employed as well as culture filtrates containing C x . Activities were determined by ability to digest the substrates and to release H 2O-soluble phenolic compounds from the grass cell-walls. The culture filtrates most active on cotton cellulose were obtained using the fungi Trichoderma viride and Fusarium solani; with grass cell-walls the most active were from T. viride, Gliocladium roseum, a species of Basidiomycetes, and one strain of Myrothecium verrucaria (IMI Strain 25 291). For the crude enzyme preparations tested, there were highly significant correlations between the digestibility of grass cell-walls and the UV-absorption of the filtrate at λ max 290 nm and at λ max 324 nm but there was no significant correlation between the digestibility of grass cell-walls and that of cotton cellulose. Partially purified C 1 and C x from two different fungal sources showed activity on both substrates. Differences in MW of the H 2O-soluble phenolic compounds obtained by treatment of grass cell-walls with C 1 and C x components suggest that these enzymes could have different modes of action. Synergism between C 1 and C x from T. koningii occurred with both substrates but with C 1 and C x from F. solani synergism only occurred with cotton cellulose.