Abstract:

The complicated and compacted structure of bamboo hindered the effect of enzymatic hydrolysis when the enzymatic degumming of bamboo was carried out. Therefore, ultrasound was employed to pretreat bamboo powders prior to enzymatic treating with the purpose of improving the efficiency of cellulase hydrolysis on bamboo powder. Results from univariate analysis indicated the preferred ultrasonic pretreatment should be carried out at room temperature for 15 min with the bath ratio of 1:30, the frequency of 20 KHz, and the power of 960W. Under the same conditions, the reducing sugar yield from cellulase hydrolysis of ultrasonic-pretreated bamboo powders increased by 34.48% compared with bamboo powders without pretreatment after the incubation for 12 h. The changes in surface structure, chemical components and crystallinity of bamboo powder with and without ultrasonic pretreatment was evaluated by scanning electron microscopy, infrared spectroscopy and X- ray diffraction. The results demonstrated that the surface structure of bamboo powders is damaged，and the number of gap and pores is increased, thus the valid surface for enzyme binding increased. The crystallinity of ultrasonic treated bamboo was decreased by 11.68% but chemical structure showed no significant change. These results suggest that ultrasound pretreatment is effective and mild without changing the properties of bamboo.

Key words: ultrasonic, cellulase, bamboo powder, reducing sugar, crystallinity