Badhan Ajay, Wang Yuxi, Gruninger Robert, Patton Donald, Powlowski Justin, Tsang Adrian, McAllister Tim
Agriculture and Agri food Canada, Lethbridge research Centre, Lethbridge, Alberta, Canada.
BMC Biotechnol. 2014 Apr 26;14:31. doi: 10.1186/1472-6750-14-31.
Efficient conversion of lignocellulosic biomass to fermentable sugars requires the synergistic action of multiple enzymes; consequently enzyme mixtures must be properly formulated for effective hydrolysis. The nature of an optimal enzyme blends depends on the type of pretreatment employed as well the characteristics of the substrate. In this study, statistical experimental design was used to develop mixtures of recombinant glycosyl hydrolases from thermophilic and anaerobic fungi that enhanced the digestion of alkaline peroxide treated alfalfa hay and barley straw by mixed rumen enzymes as well as commercial cellulases (Accelerase 1500, A1500; Accelerase XC, AXC).
Combinations of feruloyl and acetyl xylan esterases (FAE1a; AXE16A_ASPNG), endoglucanase GH7 (EGL7A_THITE) and polygalacturonase (PGA28A_ASPNG) with rumen enzymes improved straw digestion. Inclusion of pectinase (PGA28A_ASPNG), endoxylanase (XYN11A_THITE), feruloyl esterase (FAE1a) and β-glucosidase (E-BGLUC) with A1500 or endoglucanase GH7 (EGL7A_THITE) and β-xylosidase (E-BXSRB) with AXC increased glucose release from alfalfa hay. Glucose yield from straw was improved when FAE1a and endoglucanase GH7 (EGL7A_THITE) were added to A1500, while FAE1a and AXE16A_ASPNG enhanced the activity of AXC on straw. Xylose release from alfalfa hay was augmented by supplementing A1500 with E-BGLUC, or AXC with EGL7A_THITE and XYN11A_THITE. Adding arabinofuranosidase (ABF54B_ASPNG) and esterases (AXE16A_ASPNG; AXE16B_ASPNG) to A1500, or FAE1a and AXE16A_ASPNG to AXC enhanced xylose release from barley straw, a response confirmed in a scaled up assay.
The efficacy of commercial enzyme mixtures as well as mixed enzymes from the rumen was improved through formulation with synergetic recombinant enzymes. This approach reliably identified supplemental enzymes that enhanced sugar release from alkaline pretreated alfalfa hay and barley straw.
将木质纤维素生物质高效转化为可发酵糖需要多种酶的协同作用；因此，必须合理配制酶混合物以实现有效的水解。最佳酶混合物的性质取决于所采用的预处理类型以及底物的特性。在本研究中，采用统计实验设计来开发嗜热和厌氧真菌的重组糖基水解酶混合物，这些混合物可增强混合瘤胃酶以及商业纤维素酶（Accelerase 1500，A1500；Accelerase XC，AXC）对碱性过氧化氢处理的苜蓿干草和大麦秸秆的消化作用。
阿魏酸酯酶和乙酰木聚糖酯酶（FAE1a；AXE16A_ASPNG）、内切葡聚糖酶GH7（EGL7A_THITE）和聚半乳糖醛酸酶（PGA28A_ASPNG）与瘤胃酶的组合改善了秸秆消化。在A1500中加入果胶酶（PGA28A_ASPNG）、木聚糖内切酶（XYN11A_THITE）、阿魏酸酯酶（FAE1a）和β-葡萄糖苷酶（E-BGLUC），或者在AXC中加入内切葡聚糖酶GH7（EGL7A_THITE）和β-木糖苷酶（E-BXSRB），可增加苜蓿干草中葡萄糖的释放量。当将FAE1a和内切葡聚糖酶GH7（EGL7A_THITE）添加到A1500中时，秸秆的葡萄糖产量得到提高，而FAE1a和AXE16A_ASPNG增强了AXC对秸秆的活性。通过在A1500中补充E-BGLUC，或者在AXC中补充EGL7A_THITE和XYN11A_THITE，苜蓿干草中木糖的释放量增加。向A1500中添加阿拉伯呋喃糖苷酶（ABF54B_ASPNG）和酯酶（AXE16A_ASPNG；AXE16B_ASPNG），或者向AXC中添加FAE1a和AXE16A_ASPNG，可增强大麦秸秆中木糖的释放，这一结果在放大试验中得到证实。
通过与协同重组酶进行配制，提高了商业酶混合物以及瘤胃混合酶的功效。这种方法可靠地鉴定出了可增强碱性预处理苜蓿干草和大麦秸秆中糖释放的补充酶。
