Monday, April 30, 2007

The role of xyloglucanase in the total hydrolysis of lignocellulosic substrates

Zsuzsa Benko1, Katy Reczey1, Matti Siika-aho2, and Liisa Viikari3. (1) Dept. of Agric. Chemical Technology, Budapest University of Techlnology, Szent Gellert ter 4, Budapest, H-1521, Hungary, (2) VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Espoo, Finland, (3) VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Espoo, Finland

The primary cell wall of higher plants consists of at least two different polysaccharide networks, the load bearing cellulose-xyloglucan network and the pectinic polysaccharide network that may control the cell wall porosity. Xyloglucan represents up about 20-25% of primary cell wall in dicotyledonous angiosperms, about 2-5 % in grasses and about 10% in soft woods and it is believed to be a key component in cell enlargement during growth. It is highly associated with the cellulose chains, and thus degrading the xyloglucan polymer using xyloglucanases could possibly improve the total hydrolysis of lignocellulosic substrates.
In order to get more information about the role of xyloglucan eleven different ligncellulosic substrates were hydrolyzed in this study using different combinations of purified cellobiohydrolase I and II, endoglucanase II and xyloglucanase of Trichoderma reesei and Aspergillus β-glucosidase. Xyloglucanase activity had generally an improving effect on the total hydrolysis of the lignocellulosic substrates. The results indicated that the application of this enzyme activity is required to enhance the total hydrolysis especially in cases when the pretreatment of the lignocellulosic substrate was not optimal.