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

欧洲有大量的生物炼制计划，其基础是一系列不同的原料，包括草、谷物、豆类和甜菜。以草为基础的生物炼制项目位于爱尔兰、比利时、奥地利、波兰、德国和荷兰。高糖多年生黑麦草有潜力提供理想的生物精炼原料，用于生产生物乙醇和琥珀酸盐和乳酸等散装化学品，以及其他副产品，如生物复合材料和由纤维部分制成的动物饲料。这种草产量高（约15吨干重/公顷/年），非常适合英国的气候和土壤条件。它可以生长在不支持谷类作物生长的边缘土地上，因此不会危及未来的粮食供应。它需要低的年投入，特别是当种植三叶草作为氮源时，不需要投资新的播种和收获设备。这种原料现在是可用的，并且在整个英国都很丰富。从生物精炼的角度来看，它是高度可消化的（4-6%木质素），并具有高水溶性糖含量（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的好处。淀粉需要经过加热、酸和一系列酶的处理才能转化为可发酵的糖，而果聚糖可以通过使用一种酶来转化。然而，仅以乙醇和散装化学品以及生物复合材料生产为基础的草生物精炼厂在经济上不太可行，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、表面和胶体科学。它开始利用在永久黑麦草中发现的各种各样的果聚糖分子，以及由果聚糖水解酶在这些果聚糖上产生的新分子来生产新的高价值化学品。它将首先通过筛选阿伯里斯特威斯大学开发的一系列多年生黑麦草来确定生物炼制的最佳黑麦草原料，这些黑麦草将生产具有特定大小和分子结构的高产量果聚糖。将研究新的超声技术，通过机械破坏细胞壁，最大限度地从黑麦草中释放植物糖，并协助去除有色杂质。果聚糖将根据其分子大小分成不同的类别，然后将进行化学改性以生产一系列高价值的糖基聚合物和表面活性剂分子，这些分子可用于各种商业产品的配方，包括药品，化妆品，个人护理，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行为。2000年，全球对表面活性剂的需求量为1920万吨，其中以碳水化合物为基础的产品占290万吨。随着减少对石油衍生产品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贡献将根据整个草草生物精炼厂的经济效益进行评估。

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.