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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.

A 28-kDa endoglucanase was isolated from the culture filtrate of Phanerochaete chrysosporium strain K3 and named EG 28. It degrades carboxymethylated cellulose and amorphous cellulose, and to a lesser degree xylan and mannan but not microcrystalline cellulose (Avicel). EG 28 is unusual among cellulases from aerobic fungi, in that it appears to lack a cellulose-binding domain and does not bind to crystalline cellulose. The enzyme is efficient at releasing short fibres from filter paper and mechanical pulp, and acts synergistically with cellobiohydrolases. Its mode of degrading filter paper appears to be different to that of endoglucanase I from Trichoderma reesei. Furthermore, EG 28 releases colour from stained cellulose beads faster than any other enzyme tested. Peptide mapping suggests that it is not a fragment of another known endoglucanases from P. chrysosporium and peptide sequences indicate that it belongs to family 12 of the glycosyl hydrolases. EG 28 is glycosylated. The biological function of the enzyme is discussed, and it is hypothesized that it is homologous to EG III in Trichoderma reesei and the role of the enzyme is to make the cellulose in wood more accessible to other cellulases.

Cellobiose dehydrogenase from Phanerochaete chrysosporium produces H2O2 by electron transfer between cellobiose and O-2 with a lower yield than the 1:1:1 molar ratio displayed by Aspergillus niger. glucose oxidase in the similar reaction between glucose and O-2. The discrepancy could best be explained if both a Fenton's reaction and the spontaneous reactivity of the oxygen species formed were taken into account.