In vivo alpha-olefin production: a sustainable hydrocarbon source

我们社会面临的主要挑战之一是石油储备水平不断下降，我们不仅依赖石油储备来运输燃料，而且还依赖塑料、润滑油和各种石化产品。这项申请试图通过合成生物学提供一个答案：让有机体产生“石油”。尽管石油的生产主要是一个生物成因过程，但生物物质转化为石油的地球化学反应发生了数千年。因此，迫切需要寻求减少我们对化石石油依赖的解决方案。活体直接生产碳氢化合物，绕过有机质转化为石油的地球化学反应，是一个有吸引力的过程，但不幸的是，它不是使其成为一种有吸引力的可持续替代方案所需的“主流”生化反应的一部分。事实上，导致碳氢化合物如烯烃或烷烃产生的次要途径或副反应直到最近才被记录在案。不幸的是，它们在任何生物体中的存在规模和/或特异性都不足以支持工业应用，更不用说提供化石石油的有效替代品了。然而，应用合成生物学和代谢工程来修饰这些途径可能会导致这一领域的创新进展。为了迎接这些挑战，我们将把最先进的酶学和实验室进化技术与合成生物学结合起来。第一个挑战是酶法碳氢化合物生产，这一过程通常从脂肪酸开始。参与将脂肪酸转化为碳氢化合物的酶直到最近才被发现，许多酶仍然没有被研究。此外，它们的性质(底物和产品的特异性、稳定性和速率)不太可能支持工业规模的过程。我们将使用基于结构的合理工程和实验室进化来研究各种酶的使用，以创建一套全面的催化剂工具包，我们将利用该工具包生产碳氢化合物。最终，我们将尝试将这些与各种成分整合成一种细菌菌株，这种细菌可以将可再生能源转化为碳氢化合物，优先排出到外部环境，创造一个可持续的过程。这一雄心勃勃的计划解决了减少我们对化石石油依赖的迫切工业需求。通过酶的设计和新途径的开发，它将产生“产油”有机体，从而省去了大幅适应依赖石油的过程的需要，同时减少了相关的碳足迹。我们的项目将特别专注于线性α-烯烃的生产，这是一种高价值、在工业上至关重要的碳氢化合物中间体，是各种应用中的关键化学中间体，如软包装、刚性包装和管道、乘用车用合成润滑油、重型电机和齿轮油、表面活性剂、洗涤剂、润滑油添加剂和纸张施胶。目前还没有“绿色”的α-烯烃生产工艺，这是本申请试图改变的情况。

One of the main challenges our society faces is the dwindling level of oil reserves which we not only depend upon for transport fuels, but also plastics, lubricants and a wide range of petrochemicals. This application seeks to provide an answer through synthetic biology: making organisms produce "oil". Although the production of oil is mainly a biogenic process, the geochemical conversion of biological matter to oil occurs over thousands of years. Solutions that seek to reduce our dependency on fossil oil are therefore urgently needed. The direct production of hydrocarbon compounds by living organisms, bypassing the geochemical conversion of organic matter into oil, is an attractive process, but is unfortunately not part of the "mainstream" repertoire of biochemical reactions that would be required to make this an attractive sustainable alternative. Indeed, minor pathways or side-reactions resulting in the production of hydrocarbons such as alkenes or alkanes have only recently been documented. Unfortunately, these are not present in any organism to the scale and/or specificity that would support industrial application, let alone provide a valid alternative to fossil oil. However, the application of synthetic biology and metabolic engineering to modify these pathways is likely to result in innovative advances in this area. To meet these challenges, we will combine state-of-the-art enzymology and laboratory evolution techniques with synthetic biology. The first challenge is enzymatic hydrocarbon production, a process that often starts with fatty acids. The enzymes involved in converting fatty acids to hydrocarbons have only very recently been identified and many remain unstudied. Furthermore, their properties (substrate and product specificity, stability and rate) are unlikely to support an industrial scale process. We will investigate the use of a wide range of enzymes using structure-based rational engineering and laboratory evolution, in order to create a comprehensive toolkit of catalysts that we will exploit for hydrocarbon production. Ultimately, we will attempt to integrate these with various components into a bacterial strain which can convert renewables into hydrocarbons, preferentially excreted to the outside environment, creating a sustainable process. This ambitious programme addresses an urgent industrial need for reducing our dependency on fossil oil. Through enzyme design and development of new pathways, it will generate "oil"-producing organisms, hence bypassing the need to drastically adapt oil-dependent processes while reducing the associated carbon footprint. Our project will focuses in particular on production of linear alpha-olefins, a high value, industrially crucial intermediate class of hydrocarbons that are key chemical intermediates in a variety of applications, such as flexible packaging, rigid packaging and pipes, synthetic lubricants used in passenger car, heavy duty motor and gear oils, surfactants, detergents, lubricant additives and paper sizing. At present, no "green" alpha-olefin production process is available, a situation which this application seeks to change.