4. Conclusions
It has been demonstrated that WBY has great potential to be used as nutrient source for G. hansenii CGMCC 3917 to produce BC. Ultrasonication in combination with mild acid hydrolysis is an effective pre-treatment to improve the reducing sugar yield of WBY and BC yield. Moreover, the highest BC yield obtained from this pretreated WBY was almost six times as that from theuntreated WBY and nearly doubled that from the conventional chemical media. Additionally, the properties and microstructure of BC produced by WBY hydrolysates were as good as those obtained from the conventionally used chemical media.