Abstract：
Bacteria within the Paenibacillus genus are known to secrete a diverse array of enzymes capable of breaking down plant cell wall polysaccharides. We studied the extracellular xylanolytic activity of Paenibacillus xylanivorans and examined the complete range of secreted proteins when grown on carbohydrate-based carbon sources of increasing complexity, including wheat bran, sugar cane straw, beechwood xylan and sucrose, as control. Our data showed that the relative abundances of secreted proteins varied depending on the carbon source used. Extracellular enzymatic extracts from wheat bran (WB) or sugar cane straw (SCR) cultures had the highest xylanolytic activity, coincidently with the largest representation of carbohydrate active enzymes (CAZymes). Scaling-up to a benchtop bioreactor using WB resulted in a significant enhancement in productivity and in the overall volumetric extracellular xylanase activity, that was further concentrated by freeze-drying. The enzymatic extract was efficient in the deconstruction of xylans from different sources as well as sugar cane straw pretreated by alkali extrusion (SCRe), resulting in xylobiose and xylose, as primary products. The overall yield of xylose released from SCRe was improved by supplementing the enzymatic extract with a recombinant GH43 β-xylosidase (EcXyl43) and a GH62 α-L-arabinofuranosidase (CsAbf62A), two activities that were under-represented. Overall, we showed that the extracellular enzymatic extract from P. xylanivorans, supplemented with specific enzymatic activities, is an effective approach for targeting xylan within lignocellulosic biomass.
摘要：
已知类芽孢杆菌属内的细菌分泌能够分解植物细胞壁多糖的多种酶。我们研究了木聚糖类芽孢杆菌的细胞外木聚糖分解活性，并检查了在越来越复杂的基于碳水化合物的碳源上生长时分泌的蛋白质的完整范围。包括麦麸,甘蔗秸秆,山毛鱼木聚糖和蔗糖，作为控制。我们的数据表明，分泌蛋白质的相对丰度随所用碳源而变化。来自麦麸（WB）或甘蔗秸秆（SCR）培养物的细胞外酶提取物具有最高的木聚糖分解活性，与碳水化合物活性酶(CAZymes)的最大代表相吻合。使用WB放大到台式生物反应器导致生产率和总体积细胞外木聚糖酶活性的显着提高。通过冷冻干燥进一步浓缩。酶提取物在不同来源的木聚糖以及通过碱挤压（SCRE）预处理的甘蔗秸秆的解构中是有效的，产生木二糖和木糖，作为初级产品。通过用重组GH43β-木糖苷酶（EcXyl43）和GH62α-L-阿拉伯呋喃糖苷酶（CsAbf62A）补充酶提取物，可以提高从SCRE释放的木糖的总产量，代表性不足的两项活动。总的来说,我们发现木聚糖胞外酶提取物，补充特定的酶活性，是在木质纤维素生物质中靶向木聚糖的有效方法。
