Identification and characterization of components involved in mannan synthesis to increase lignocellulosic biofuel production

植物生物质是生物燃料和生物能源生产的丰富可再生资源。在生物能源生产过程中，植物来源的糖，如淀粉、蔗糖、纤维素和半纤维素被微生物（酵母、细菌）用于发酵，以生产所需的产品。主要的粮食作物，如玉米和甘蔗，目前被用于生产第一代生物燃料。随着能源需求的稳步增长，能源生产需求和粮食供应之间的优先竞争将显著增加。作为回应，美国和欧洲政府要求在5到7年内从非粮食作物中提取可持续数量的可再生燃料（第二代生物燃料）。实现这一目标需要广泛的基础研究和科学进步，以优化和促进非食用植物组织（即木质纤维素原料）的发酵过程。促进木质纤维素原料发酵的一个有希望的方法是增加植物细胞壁中C6糖的含量，例如甘露聚糖。植物细胞壁主要由纤维素、半纤维素和木质素组成。只有纤维素和半纤维素含有C6糖。在纤维素中，这些糖以晶体阵列排列，微生物发酵最难以接近。半纤维素中的C6糖，如甘露聚糖，更容易被微生物酶接近，因此是植物细胞壁工程的合适目标。作为DFG的一员，我建议鉴定和表征甘露聚糖合成中涉及的成分，以增加植物细胞壁中葡甘露聚糖的含量。这项工作将产生甘露聚糖生物合成的基本知识，这将有助于通过改进发酵来促进生物燃料的生产。为了实现这一目标，我将(1)使用计算机分析来过滤和分析共表达数据库，以识别与甘露聚糖生物合成中已知成分共表达的基因，并将使用现有数据集生成一组新的候选基因。(2)从分子和生化水平对候选甘露聚糖进行分析，检测候选甘露聚糖在甘露聚糖生物合成和全球植物代谢中的作用。（拟南芥将被用作模式植物。）(3)利用生物信息学方法和计算建模来预测哪些成分的组合以及哪些成分的表达和调控会导致植物细胞壁中甘露聚糖含量的增加。我假设这些结果将导致甘露聚糖生物合成的近乎完整的画面。这项工作的最终目标是创造一种在植物细胞壁中增加甘露聚糖含量的植物，通过改进发酵来促进生物燃料的生产。

Plant biomass serves as an abundant renewable source for biofuel and bioenergy production. In bioenergy production processes, plant-derived sugars such as starch, sucrose, cellulose, and hemicellulose are used for fermentation by microorganisms (yeast, bacteria) to produce desired products. Primarily food crops, like Zea mays (corn) and Saccharum officinarum (sugarcane) are currently used for the production of first-generation biofuels. As energy demand steadily increases the competing priorities between energy production needs and food supply will grow significantly. In response, the US and European governments have mandated that a sustainable amount of renewable fuel be derived from non-food crops (second-generation biofuels) in five to seven years. Achieving this mandate requires extensive basic research and scientific advancements to optimize and boost the fermentation process of non-food plant tissues, namely lignocellulosic feedstocks. A promising approach to facilitate fermentation of lignocellulosic feedstocks is to increase the C6 sugar content, e.g. mannans, in plant cell walls. Plant cell walls are mainly composed of cellulose, hemicellulose, and lignin. Only cellulose and hemicellulose contain C6 sugars. In cellulose these sugars are packed in crystalline arrays and are least accessible to microbial fermentation. The C6 sugars in hemicellulose, like mannans, are better accessible to microbial enzymes and are therefore a suitable target for plant cell wall engineering. As a DFG fellow, I propose to identify and characterize components involved in mannan synthesis to increase the glucomannan content in plant cell walls. This work will generate basic knowledge of mannan biosynthesis that will help to boost biofuel production through improved fermentation. To reach this goal I will (1) use an in silico analysis to filter and analyze coexpression databases to identify genes co-expressed with known components involved in mannan biosynthesis and will use existing data sets to generate a new set of candidate genes. (2) analyze the top candidates on a molecular and biochemical level to detect the candidates role in mannan biosynthesis and in global plant metabolism. (Arabidopsis thaliana will be used as a model plant.) (3) use a bioinformatics approach and computational modeling to predict which combination of components and which expression and regulation of components will lead to an increased mannan content in plant cell walls. I hypothesize that these results will lead to a near complete picture of mannan biosynthesis. The ultimate goal of this work is to create a plant with increased mannan content in plant cell walls to boost biofuel production through improved fermentation.