ABSTRACT
One of the most efficient cellulose-degrading and industrially important fungus T. reesei has at least five EGLs (Table 20.1) (Foreman et al., 2003; Sandgren et al., 2005). Of these five EGLs, EGI and EGLII are the most abundant. Still, all five EGLs are induced during growth on cellulose and repressed in the presence of d-glucose (Foreman et al., 2003; Ilmén et al., 1997). The substrate specificity of EGLs is not limited to cellulose. For instance, EGIII has activity against cellulose, b-1,3-1,4-glucan, xyloglucan and xylan (Eriksson et al., 2002; Sprey and Bochem, 1993) and EGVI was described to prefer xyloglucan as a substrate (Grishutin et al., 2004). These different substrate specificities may likely be an explanation for the occurrence of many EGLs. For another well-studied fungus, Aspergillus nidulans, three EGLs have been described (Table 20.2; EglA, EglB, and EglC). Although these EGLs all have activity on carboxymethyl cellulose, EglA and EglB have the highest activity on cellulose-based substrates (Bauer et al., 2006).
