里氏木霉与黑曲霉混合发酵产纤维素酶的条件优化

摘要

This paper deals with the optimization of fermentation conditions for cellulase production from corn stover treated by alkaline hydrogen peroxide by bothTrichoderma reesei andAspergillus niger. Four fermentation conditions including delay time ofAspergillus niger inoculation, inoculum ratio betweenTrichoderma reesei andAspergillus niger, fermentation time and solid-to-liquid ratio were investigated by one-factor-at-a-time experiments and their respective appropriate levels were determined for the optimization of these fermentation conditions using a Box-Behnken design coupled with response surface analysis. The optimal fermentation conditions for cellulase production were as follows:Aspergillus niger was inoculated 36 h later thanTrichoderma reesei at a ratio of 1:5 between them; the fermentation medium was at a solid-to-liquid ratio of 2:50 (m/V) and pH was 5.0 and contained 0.4%Tween-80 and itsfi lled quantity was 50 mL in a 250 mLfl ask; the fermentation period was 7 d. Thefi nal products obtained under these conditions showed afi lter paper activity of 1.224 IU/mL and aβ-glucosidase activity of 0.315 IU /mL. HPLC analysis indicated that more complete cellulase system with enhanced hydrolysis effi ciency on lignocellulose for production of fermentable sugars was produced by jointly Trichoderma reesei andAspergillus niger than either of them.%为提高纤维素酶酶解秸秆产糖效果，以碱性双氧水处理过的玉米秸秆为发酵基质，进行里氏木霉与黑曲霉混合发酵的研究。通过单因素试验确定黑曲霉延迟接种时间、里氏木霉与黑曲霉接种比例、发酵时间和固液比4个因素的最优水平。在此基础上，采用Box-Behnken响应面设计对混合发酵产酶条件进行优化，获得最佳产酶条件：黑曲霉延迟接种时间36h，里氏木霉与黑曲霉接种比例5：1、发酵时间7d、固液比2：50(m/V)、吐温-80体积分数0.4%、pH 5.0和装液量50mL/250mL。此时，滤纸酶力(FPA)可达1.224 IU/mL，β-葡萄糖苷酶活力(β-GA)可达0.315 IU/mL。采用高效液相色谱法，对最佳条件下的纤维素酶酶解秸秆的水解液进行检测。结果表明，两菌株混合发酵较单菌株发酵的纤维素酶系更加完整，且降解木质纤维素类原料产可发酵性糖的能力增强。