Production of isoprenoid-based biofuel in algae using a synthetic biology approach

世界正面临着一个相当大的挑战，那就是用基于生物燃料等清洁能源技术的经济来补充并最终取代以化石燃料为基础的经济。目前，商业上可用的生物燃料（如生物乙醇和生物柴油）是从玉米和大豆等农作物中提取的。然而，在利用宝贵的农业用地生产生物燃料作物以及这些技术的可持续性和能源平衡方面存在重大关切。一种潜在的替代生物燃料来源是微藻——一种不需要肥沃土地种植的水生光合生物；生长速度比植物快得多，并且可以积累大量的高能量化合物，如油。此外，这种水生养殖可以与工业排放的二氧化碳和富含营养的废水等废物相结合，从而利用这些废物促进藻类生长。然而，工业规模的微藻生物燃料种植面临着相当大的挑战，不仅在技术可行性方面，而且在经济和实现净正能量平衡方面。人们认识到，成功可能需要开发优良的藻类菌株，其中基因工程方法已被用于从根本上改变和定制细胞代谢，以实现工业条件下最大的生物燃料生产力。目前，制造这种菌株所需的分子工具有限，藻类代谢工程仍处于起步阶段。在这个项目中，我们将沿着“合成生物学”技术的路线开发先进的藻类工具，该技术目前被用于设计和创造新的细菌和酵母菌株。我们的方法的一个特别吸引人的特点是，我们将利用将新基因引入两个独立的遗传室的能力，即细胞核和叶绿体，从而允许采用多种新基因的复杂工程策略，并在叶绿体内创造新的生物合成途径，但可以由细胞核调节。我们将通过创造一系列设计藻类来验证这项新技术，这些藻类可以产生两种潜在的有用的燃料分子——短链碳氢化合物异戊二烯和酒精香叶醇。

The World is faced with the considerable challenge of supplementing, and ultimately replacing, its fossil fuel-based economy with one based on clean energy technologies such as biofuels. Currently, commercially available biofuels (e.g. bioethanol and biodiesel) are derived from crop plants such as maize and soybean. However, there are major concerns regarding both the use of valuable agricultural land for production of biofuel crops, and the sustainability and energy balance of such technologies. A potential alternative source of biofuels is microalgae - aquatic photosynthetic organisms that do not require fertile land for cultivation; grow considerably faster than plants, and which can accumulate significant quantities of high-energy compounds such as oils. Furthermore, such aquatic cultivation could be coupled to waste streams such as CO2 output from industry and nutrient-rich effluent, thereby using this waste to promote algal growth. However, industrial-scale cultivation of microalgae for biofuels faces considerable challenges, not just in terms of technical feasibility, but also in terms of the economics and achieving a net positive energy balance. It is recognised that success will probably require the development of superior algal strains in which genetic engineering methods have been used to radically alter and tailor the cell metabolism's towards maximal biofuel productivity under industrial conditions. Currently, the molecular tools needed to create such strains are decided limited and algal metabolic engineering is still in its infancy. In this project, we will develop advanced tools for algae along the lines of the 'synthetic biology' technology now being used to design and create novel bacterial and yeast strains. A particularly, attractive feature of our approach is that we will exploit the ability to introduce new genes into two separate genetic compartments, the nucleus and the chloroplast, thereby allowing elaborate strategies for engineering that employ multiple new genes and create novel biosynthetic pathways within the chloroplast, but which can regulated from the nucleus. We will validate this new technology by creating a series of designer algae that produce two potentially useful fuel molecules - the short-chain hydrocarbon, isoprene and the alcohol, geraniol.