Sustainable Bioenergy Centre: Cell wall sugars programme

为了实现从植物生物量（木质纤维素）生产生物燃料的目标，植物细胞壁可以通过产生单糖（糖化）的水解酶的混合物来降解。在加入混合酶之前，对生物质原料进行预处理以增加纤维素和半纤维素的酶可及性。然后将释放出来的糖进行工业发酵，生产乙醇和丁醇等生物燃料。木质纤维素生物燃料技术的可行性将取决于最大限度地从生物质中提取可发酵糖，并将加工成本降至最低。目前，富含戊糖的半纤维素木聚糖成分在草和木材等原料中占20- 30%，但很难使用。这种木聚糖阻碍酶进入纤维素，部分通过与木质素的连接。主要问题之一是它是一种支链聚合物，很难被酶分解。酸处理分解半纤维素可以产生抑制剂，阻止有效的微生物发酵和减少糖的产量。本项目旨在更好地了解半纤维素合成的遗传控制，特别是生物质中的支化木聚糖成分，以及木聚糖支化对酶可及性的影响。它将开发植物多糖合成机制的综合表征，以及合成酶如何在蛋白质复合物中协同工作。该计划还将发现并表征将该成分分解为单糖的有效酶。该项目将提供高通量、详细、定量分析生物质半纤维素和分解它们的酶活性的技术。在此基础上，将提出植物育种或改良策略，以及水解酶的选择，以降低使用生物质支链木聚糖成分的成本，并释放纤维素进行糖化。剑桥大学研究细胞壁合成和开发多糖和水解酶分析技术的项目得到了纽卡斯尔大学酶发现的支持，由David Bolam博士和Harry Gilbert教授合作。壳牌全球解决方案是该计划的合作者，提供重要的工业视角和生物信息学支持。用于方法开发和细胞壁多糖分析的其他酶将与世界酶生产领导者诺维信合作提供和研究。

To achieve the goal of producing biofuel from plant biomass (lignocellulose), the plant cell wall can be degraded by a cocktail of hydrolase enzymes that generate monosaccharide sugars (saccharification). Biomass feedstocks are pretreated to increase enzyme accessibility of the cellulose and hemicelluloses prior to addition of the enzyme cocktails. The released sugars are then industrially fermented to generate biofuels such as ethanol and butanol. The viability of lignocellulosic biofuel technology will depend on maximising the fermentable sugar from biomass, and minimising the costs of processing. Currently, it is difficult to use the pentose-rich hemicellulose xylan component which constitutes 20- 30% of most feedstocks such as grass and wood. This xylan impedes enzyme access to the cellulose, in part through links with the lignin. One of the main problems is that it is a branched polymer that is difficult to break down with enzymes. Acid treatments to break up the hemicellulose can generate inhibitors that prevent effective microbial fermentation and reduce the yield of sugars. This programme aims to achieve a better understanding of the genetic control of hemicellulose synthesis, especially the branched xylan component of biomass, and the impact of xylan branching on enzyme accessibility. It will develop a comprehensive characterisation of plant polysaccharide synthesis machinery, and how the synthesis enzymes work together in protein complexes. The programme will also discover and characterise effective enzymes that break down this component to monosaccharides. The programme will deliver enabling technologies for high throughput, detailed, quantitative analysis of biomass hemicelluloses and the activity of the enzymes that break them down. Based on this knowledge, strategies of plant breeding or modification, and also of hydrolytic enzyme selection, will be proposed in order to reduce the costs of use of the branched xylan component of biomass, and to release the cellulose for saccharification. The programme in Cambridge to study cell wall synthesis and to develop the polysaccharide and hydrolase profiling technologies is supported by enzyme discovery in the University of Newcastle, with Dr David Bolam and collaboration with Professor Harry Gilbert. Shell Global Solutions are collaborators in the programme, providing an important industrial perspective and bioinformatic support. Additional enzymes for method development and for analysis of cell wall polysaccharides will be provided and studied in collaboration with Novozymes, the world leader in enzyme production.