ENZYMATIC-HYDROLYSIS OF ISOLATED AND FIBER-BOUND GALACTOGLUCOMANNANS FROM PINE-WOOD AND PINE KRAFT PULP

Fibre-bound and isolated galactoglucomannans from pine-wood and pine k raft pulp were hydrolysed with purified mannanases from Trichoderma re esei and Bacillus subtilis. The isolated galactoglucomannans from both wood and pulp could be hydrolysed fairly extensively with both enzyme s. In addition to mixed oligomers, the fungal mannase produced mannobi ose as the main hydrolysis product whereas the bacterial mannanase pro duced mannobiose, mannotriose and mannotetraose. Both enzymes hydrolys ed the native galactoglucomannan in finely ground pine-wood, whereas g alactoglucomannan in pine kraft pulp was only hydrolysed by the T. ree sei mannanase. Thus, mannanases exhibit different specificities on fib re-bound, modified substrates. In spite of the high enzyme loading, th e degree of hydrolysis of fibre-bound substrates did not exceed 10% of the theoretical, probably due to poor accessibility of the substrates .