Fig. 8

Schematic model illustrating the principle for constructing the BGLA-overexpressing cellulase system with pleiotropic functions. The cellulase expression in T. reesei (SP4) is repressed through the carbon catabolite repressor Cre1 when glucose is present. Deletion of the cre1 gene results in glucose derepression and enhanced cellulase expression. Further overexpression of the A. niger bglA gene produces the T. reesei (SCB18) cellulase with high efficiency for saccharification of different cellulosic substrates. Meanwhile, the cellulase in T. reesei could also be induced by β-disaccharides (cellobiose and sophorose). The BGLA-overexpressing cellulase system produced by T. reesei (SCB18) can conversely synthesize these β-disaccharides with its transglycosylation activity from glucose as carbon source, which could be further used as cellulase inducers