[Effect of supercritical CO2 to cellulase reaction]

The effects of pretreatment of supercritical carbon dioxide (SC-CO2) on the supramolecular structure of cellulose and the cellulase catalyzed reaction were investigated. The cellulase activity was not affected when it was treated with SC-CO2 at 10MPa and at 50 degrees C for 30 min. But when the cellulase was treated by SC-CO2 in the presence of cellulose, the catalytic activity of the cellulase was lost. The cellulose pretreated with or without cellulase under the same SC-CO2 condition was then hydrolyzed with tresh crude cellulase. The final reducing sugar yield from the hydrolysis of the cellulose pretreated with cellulase was higher than that of the cellulose pretreated without cellulase. It was also found that the improvement of the enzymolysis had a direct relevance with the amount of cellulase used during the SC-CO2 pretreatment. The moisture content of cellulose before SC-CO2 pretreatment had an obvious influence on the subsequent enzymolysis. When the moisture content of cellulose was 60% (W/W), the reducing sugar yield was higher than when the moisture content was over 100% (W/W). The FT-IR spectra showed that the structure of the cellulose pretreated with cellulase under the SC-CO2 condition was different from that of the cellulose pretreated without cellulase. In the presence of the enzyme, the strength of the hydrogen bonds and the I beta phase at 710cm(-1) in the crystalline cellulose was weakened. These results suggest that the change in the cellulose structure induced by the SC-CO2 treatment favous the subsequent enzymolysis.