Acid hydrolysis of bacterial cellulose reveals different modes of synergistic action between cellobiohydrolase I and endoglucanase I

Authors


G. Johansson, Department of Biochemistry, University of Uppsala, PO Box 576 S-75 123 Uppsala, Sweden. Fax: + 46 18 552139, Tel.: + 46 18 4714477, E-mail: Gunnar.Johansson@biokem.uu.se

Abstract

Intact and partially acid hydrolyzed cellulose from Acetobacter xylinum were used as model substrates for cellulose hydrolysis by 1,4-β-d-glucan-cellobiohydrolase I (CBH I) and 1,4-β-d-endoglucanase I (EG I) from Trichoderma reesei. A high synergy between CBH I and EG I in simultaneous action was observed with intact bacterial cellulose (BC), but this synergistic effect was rapidly reduced by acid pretreatment of the cellulose. Moreover, a distinct synergistic effect was observed upon sequential endo–exo action on BC, but not on bacterial microcrystalline cellulose (BMCC). A mechanism for endo–exo synergism on crystalline cellulose is proposed where the simultaneous action of the enzymes counteract the decrease of activity caused by undesirable changes in the cellulose surface microstructure.

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