Isolation fractionation and modification of fructans from rye-grass to produce novel biosurfactants and polymers as part of a rye-grass biorefinery

欧洲有大量基于不同原料的生物精炼倡议，包括草、谷物、豆类和甜菜。草基生物精炼倡议位于爱尔兰、比利时、奥地利、波兰、德国和荷兰。高糖多年生黑麦草有潜力为生产生物乙醇和琥珀酸、乳酸等大宗化学品提供理想的生物精炼原料，以及其他副产品流，如生物复合材料和从纤维组分生产的动物饲料。这种草产量高(约15吨干重量/公顷/年)，非常适合英国经历的气候和土壤条件。它可以生长在不支持谷类作物生长的边际土地上，因此不会危及未来的粮食供应。它需要较低的年度投入，特别是在以三叶草作为氮源种植的情况下，而且不需要投资于播种和收获的新设备。这种原料现在可以买到，而且在整个英国都很丰富。从生物精炼的角度来看，它具有高度的可消化性(4-6%的木质素)和高的水溶性糖含量(高达40%)。它还具有以水溶性糖、果聚糖而不是淀粉的形式储存碳水化合物储备的好处。与淀粉不同，淀粉需要加热、酸和一系列酶处理才能转化为可发酵的糖，而果聚糖可以通过使用单一酶来转化。然而，仅基于乙醇和散装化学品以及生物复合材料生产的草生物精炼厂不太可能在经济上可行，有必要从分离的果聚糖分子中生产额外的高价值化学品。这个项目涉及一个多学科的科学家团队，他们的技能互补，从植物生物学到生物化学、化学以及表面和胶体科学。它致力于利用在黑麦草中发现的各种果聚糖分子，以及通过果聚糖水解酶对这些果聚糖进行作用而产生的新分子，以生产新型高价值化学品。它将通过筛选Aberystwyth大学开发的一系列多年生黑麦草来初步确定生物精炼厂的最佳黑麦草原料，这些多年生黑麦草将产生具有特定大小和分子结构的高产果聚糖。将研究新的超声波技术，通过机械破裂细胞壁来最大限度地释放黑麦草中的植物糖，并帮助去除有色杂质。果聚糖将根据其分子大小被分成不同的类别，然后进行化学修饰，以产生一系列高价值的糖基聚合物和表面活性分子，这些分子可用于配制一系列商业产品，包括药品、化妆品、个人护理和涂料等。它们在这些产品中的作用是帮助颗粒的分散、油的乳化和控制流变性。2000年全球对表面活性剂的需求量为1920万吨，其中碳水化合物产品的需求量为290万吨。随着减少对石油衍生产品的依赖的压力越来越大，对可再生资源生产的生物表面活性剂的需求可能会迅速扩大。在项目过程中生产的特种化学品的价值的贡献将根据整个草生物精炼厂的经济情况进行评估。

There are a large number of biorefinery initiatives in Europe based on a range of different feedstocks including grass, cereals, legumes and sugar beet. Grass-based biorefinery initiatives are located in Ireland, Belgium, Austria, Poland, Germany, and the Netherlands. High-sugar perennial rye-grass has the potential to provide an ideal biorefinery feedstock for the production of bio-ethanol and bulk chemicals such as succinates and lactic acid, with other co-product streams such as biocomposite materials and animal feeds manufactured from the fibre fraction. This grass is high yielding (ca.15 tonne dry wt./hectare/year) and is ideally suited to the climatic and soil conditions experienced in the UK. It can grow on marginal land that will not support the growth of cereal crops and hence will not jeopardise future food supplies. It requires low annual inputs, especially when grown with clover as a source of nitrogen, and does not require investment in new equipment for sowing and harvesting. This feedstock is available now and is abundant throughout the UK. From a biorefining perspective, it is highly digestible (4-6% lignin) and has a high water soluble sugar content (up to 40%). It also has the benefit of storing its carbohydrate reserves in the form of the water-soluble sugar, fructan, rather than starch. Unlike starch, which requires treatments with heat, acids and a series of enzymes, for conversion to a fermentable sugar, fructan can be converted through the use of a single enzyme. A grass biorefinery based on ethanol and bulk chemicals as well as biocomposites production alone, however, is unlikely to be economically viable and it is necessary to produce additional high value chemicals from the fructan molecules isolated. This project involves a multidisciplinary team of scientists with complementary skills ranging from plant biology to biochemistry, chemistry and surface and colloid science. It sets out to utilise the diverse range of fructan molecules found in perrential ryegrass, as well as novel molecules created by the action of fructan hydrolysing enzymes on these fructans to produce novel high value chemicals. It will initially identify the optimum rye-grass feedstock for a biorefinery by screening a range of perennial ryegrasses developed at Aberystwyth University that will produce high yields of fructans with specific size and molecular architecture. Novel ultrasound technologies will be investigated to maximise the release of plant sugars from the rye-grass through mechanical rupture of cell walls and to assist in the removal of coloured impurities. The fructans will be separated into different classes according to their molecular size and will then be chemically modified to produce a range of high-value sugar-based polymer and surfactant molecules that can be used in the formulation of a broad range of commercial products including, pharmaceuticals, cosmetics, personal care, coatings, etc.. Their role in these products is to aid the dispersion of particles, the emulsification of oils and in the control the rheological behaviour. The global demand for surfactants in 2000 was 19.2 million tonnes with carbohydrate based products accounting for 2.9 million tonnes. The demand for biosurfactants produced from renewable sources is likely to expand rapidly, with increasing pressure to reduce the reliance on petroleum derived products. The contribution of the value of the speciality chemicals produced during the course of the project will be assessed with regards to the economics of a total grass grass biorefinery.