This study examined the effects of different pretreatments of birch sawdust on the production and activity of polysaccharides by Inonotus obliquus, and in order to explore the mechanism, structural characterization and analysis were carried out. The result clearly indicated that alkali treatment, ozone treatment, and alkali combined with ozone treatment of birch sawdust could be all helpful for the production of active polysaccharide by I. obliquus. Among four pretreatment groups, birch sawdust treated with alkali showed the highest increase in the exo-polysaccharide content (39.90%) and the inhibition rate of α-glucosidase (80.78%) within 11 days by the mycelium of I. obliquus through deep fermentation, in comparison to water-washed birch sawdust. Through a single-factor analysis and orthogonal experimental design, the optimum alkali treatment condition was as follows: NaOH concentration 1%, temperature 60 °C, and time 3 h. Moreover, the structural characteristics of pretreated birch sawdust with the optimum alkali treatment condition before and after fermentation by the mycelium of I. obliquus was performed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The results showed that alkali treatment destroyed the lignin structure of birch sawdust, exposed the cellulose in the amorphous area, reduced the crystallinity of lignocellulose, and damaged the surface structure of birch sawdust, which had a further damage and a greater degradation degree of birch sawdust after fermentation, indicating that alkali pretreatment was beneficial for utilization of birch sawdust by I. obliquus.

本研究考察了桦木锯末不同预处理对桦褐孔菌多糖产量和活性的影响，并为探索其作用机制，进行了结构表征和分析。结果清楚地表明，碱处理、臭氧处理以及碱联合臭氧处理桦木锯末均有助于I.obliquus生产活性多糖。在4个预处理组中，碱处理桦木锯末的外多糖含量（39.90%）和α-葡萄糖苷酶抑制率（80.78%）在11天内被I.obliquus菌丝体增加最多。通过深度发酵，与水洗桦木锯末相比。通过单因素分析和正交试验设计，最佳碱处理条件为：NaOH浓度1%，温度60℃，时间3h。此外,在最佳碱处理条件下预处理桦木锯末的结构特征在斜交木霉菌丝体发酵前后的结构特征通过傅里叶变换红外光谱、X 射线衍射和扫描电子显微镜进行。结果表明，碱处理破坏了桦木屑的木质素结构，使无定形区的纤维素暴露出来，降低了木质纤维素的结晶度，破坏了桦木屑的表面结构，对桦木屑的破坏程度更大，降解程度更大。发酵后，表明碱预处理有利于I. obliquus对桦木锯末的利用。