Xin Wei, Wang Xiu-Dao, Yin Zhuo-Rong, Gao Pei-Ji
State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China.
Sheng Wu Gong Cheng Xue Bao. 2004 Sep;20(5):770-3.
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.
研究了超临界二氧化碳（SC-CO2）预处理对纤维素超分子结构及纤维素酶催化反应的影响。纤维素酶在10MPa、50℃条件下用SC-CO2处理30min后活性未受影响。但当纤维素酶在纤维素存在下用SC-CO2处理时，纤维素酶的催化活性丧失。然后，将在相同SC-CO2条件下经或未经纤维素酶预处理的纤维素用新鲜粗纤维素酶进行水解。经纤维素酶预处理的纤维素水解得到的最终还原糖产量高于未经纤维素酶预处理的纤维素。还发现酶解效果的提高与SC-CO2预处理过程中所用纤维素酶的量直接相关。SC-CO2预处理前纤维素的含水量对后续酶解有明显影响。当纤维素含水量为60%（W/W）时，还原糖产量高于含水量超过100%（W/W）时。傅里叶变换红外光谱（FT-IR）表明，在SC-CO2条件下经纤维素酶预处理的纤维素结构与未经纤维素酶预处理的纤维素结构不同。在酶存在的情况下，结晶纤维素中氢键的强度以及710cm-1处的Iβ相减弱。这些结果表明，SC-CO2处理引起的纤维素结构变化有利于后续的酶解。
