“…However, cellulases are relatively large enzymes, and cannot fit through most of the spaces in the intact vascular layer of straw (Cowling andKirk 1976, Thompson et al 1992). Thus, physical, chemical, and thermal pretreatments are employed to increase the penetration of cellulases into this lignocellulose matrix (Marsden and Gray 1986, Cowling and Kirk 1976, Fan et al 1982. Many pretreatments have been developed, including acids (Knappert et al 1980, Goldstein et al 1983, alkalis (Playne 1984, Weimer et al 1986), organosolvents (Avgerinos and Wang 1983), steam explosion (Playne 1984, Taylor 1981, physical treatments, and others.…”