15 NSFBIO - Synthetic Biology for Lignin Utilization

我们目前对化石燃料的依赖是不可持续的，显然需要寻找可再生燃料和化学品的替代来源，以满足不断增长的全球人口的需求。在开发将废弃植物材料（生物质）转化为糖的技术方面，人们已经做了大量的工作，这些糖可以发酵为我们的汽车、火车和飞机生产生物乙醇。这依赖于酶，就像洗涤剂中使用的酶一样，来分解植物材料，以便将其转化为生物燃料——化石燃料的直接替代品。虽然现有的技术可以做到这一点，但它实在太昂贵了。那么我们怎样才能使它更便宜呢？植物细胞壁含有纤维素，正是这种聚合物可以分解成糖来制造燃料。然而，多达三分之一的植物材料是由一种叫做木质素的粘性棕色化合物组成的。目前，商业发电厂对这种燃料的利用远远不足，主要是燃烧来发电。这是一个巨大的浪费，也是生物燃料目前如此昂贵的原因之一。木质素实际上是一种非常有价值的化合物，使用合适的酶，可以转化为有用的产品，如化学品、塑料甚至碳纤维。这些材料不仅是可再生和可持续的，而且它们的高价值将使生物燃料更便宜。和往常一样，大自然已经有了答案。我们发现微生物可以以木质素为食物来源，并进化出强大的酶来分解这种抗性化合物。我们计划研究这些酶，并在新的系统中将它们连接在一起，以提高它们的效率。我们将利用遗传学来帮助我们进化出更好的酶，计算出它们的3D结构，并使用先进的计算机模型来计算出最佳组合。如果我们取得成功，我们就有可能使生物燃料生产在商业上可行，并创造一系列新的植物性产品。其结果是，运输燃料将不再依赖日益减少的化石燃料储备，而是可持续的，对环境更友好。

Our current reliance on fossil fuels is unsustainable and there is a clear need to find alternative sources of renewable fuels and chemicals to meet the needs of an expanding global population. A vast amount of work has been done in developing the technologies to turn waste plant material (biomass) into sugar that can be fermented to produce bioethanol for our cars, trains and planes. This relies on enzymes, like those used in washing detergents, to break down the plant material so that that it can be converted into biofuels - a direct alternative to fossil fuels. Although the technology now exists to do this, it is simply too expensive. So how can we make it cheaper?Plant cell walls contain cellulose and it is this polymer that can be broken down into sugars to make fuels. However, up to one-third of plant material is made up of a sticky brown compound called lignin. This is currently vastly underused in commercial plants and it is mainly burned to generate power. This is a huge waste, and one of the reasons that biofuels are currently so expensive. Lignin is actually a very valuable compound, and with the right enzymes, can be turned into useful products such as chemicals, plastics and even carbon-fibre. Not only would these materials be renewable and sustainable, their high value would make biofuels cheaper.As usual, nature already has the answer. We have found microbes that can live on lignin as a food source and have evolved powerful enzymes break this resistant compound apart. We plan to research these enzymes and link them together in new systems to make them efficient. We will use genetics to help us evolve better enzymes, work out their 3D structures and use advanced computer models to work out the best combinations. If we succeed, we have the potential to make biofuel production commercially viable and create a new range of plant-based products. The result will be transportation fuels that don't rely on dwindling fossil fuel reserves, are sustainable and are kinder to the environment.