Monday, April 29, 2013
Exhibit Hall
A cellulase cocktail was prepared from cellulases from Aspergillus aculeatus ZLF and Trichoderma reesei FST-1. The ability of this enzyme cocktail to release glucose from Delignined Corncob Residues (DCCR) was tested. An apparent synergism was observed between T. reesei and A. aculeatus cellulases. Significantly improved saccharification was detected in enzyme cocktails. Ethanol fermentation using cellulases from T. reesei and enzyme cocktails revealed much faster rate of ethanol production in A. aculeatus cellulase supplemented enzyme cocktails. Interestingly, the filter paper activity (FPA), a widely used parameter of cellulases representing saccharifying abilities, decreased in the enzyme cocktail, suggesting uncorrelated FPA and saccharification. This confirms the complexity of enzyme catalyzed cellulose degradation, in particular the significant but largely ignored role that accessibility plays in this chemical reaction. To test a previously established hypothesis that in b-glucosidases in Aspergillus cellulases improve the saccharifying ability of T. reesei cellulases during an Aspergillus-Trichoderma synergism, the dominant b-glucosidase in A. aculeatus was purified to homogeneity and supplemented to T. reesei cellulases. To our surprise, significant improvement of saccharification with the resulting enzyme cocktail was not observed. These results showed that, in contrary to previous beliefs, other Aspergillus proteins may be the decisive factor that enhances the saccharification reactions catalyzed by cellulases from Trichoderma.