Systems biology of the butanol-producing Clostridium acetobutylicum: new source of biofuel and chemicals/COSMIC2

到2030年，全球能源消费预计将增长57%。化石燃料无法满足这一需求，因为它们的持续使用正在导致全球变暖，而且无论如何，它们是一种有限的储备，将在本世纪末之前耗尽。从天然植物材料中提取的液体燃料（生物燃料）是最有希望用于运输部门的替代能源。在这方面，一种叫做丁醇的醇由于其优于乙醇和生物柴油的特性，目前正受到相当大的关注。丁醇比乙醇具有更高的能量含量，可以利用现有的汽油供应和分销渠道，可以与汽油以更高的浓度混合而无需改装发动机，提供更好的燃料经济性，并且与乙醇不同，具有作为航空燃料的潜力。传统上，丁醇是由一种叫做乙酰丁酸梭菌（Clostridium acetobutylicum）的细菌在含糖培养基上生长时产生的。发酵过程被称为丙酮-丁醇-乙醇（ABE）过程。在上世纪上半叶，ABE工艺的重要性/规模仅次于酵母乙醇生产。然而，随着石化工业的出现，该工艺变得不经济，并从20世纪60年代起在西方世界被放弃。这一过程最近在中国和巴西重新建立起来，在那里较低的运营成本使基于低效的20世纪技术的过程变得经济。为了在西方世界被采用，需要一个更有效的过程。它的衍生将依赖于所用细菌菌株的改进。然而，这种菌株的合理创造需要对细胞内催化和控制发酵产物形成的复杂过程有更详细的了解。更好地理解这个过程是本建议的总体目标。为此，一个新的整体方法称为系统生物学将被使用，它涉及数学建模和实验测试的迭代循环。在早期的一轮融资中，开发出了关键的基因工具和方法，可以对选定的基因进行精确的改变，并对后果进行评估。

By 2030, worldwide energy consumption is projected to grow by 57%. Fossil fuels cannot meet this demand, as their continued use is causing global warming and in any case are a finite reserve that will be exhausted before the end of this century. Liquid fuels derived from natural plant material (biofuels), are the most promising alternative energy source for use in the transportation sector. In this regard, an alcohol called butanol is currently receiving considerable interest due to its superior properties compared to ethanol and biodiesel. Butanol has a higher energy content than ethanol, can make use of existing petrol supply and distribution channels, can be blended with petrol at higher concentrations without engine modification, offers better fuel economy and has, unlike ethanol, potential as aviation fuel. Traditionally, butanol is produced by a bacterium called Clostridium acetobutylicum when growing on growth media containing sugars. The fermentation process is known as the Acetone-Butanol-Ethanol (ABE) process. In the first hald of the last century, the ABE process was second in importance/ scale only to ethanol production from yeast. However, with the advent of the petrochemical industry, the process became uneconomic and was abandoned in the western world from the 1960s onwards. The process has recently been re-established in China and Brazil, where lower operating costs make a process based on inefficient 20th century technology economic. For adoption in the western world, a more efficient process is required. Its derivation will be reliant on improvements to the bacterial strains employed. However, the rational creation of such strains will require a more detailed understanding of the complex processes within the cell that catalyse and control the formation of fermentation products. Deriving a better understanding of the process is the overall objective of this proposal. For this, a new holistic approach termed systems biology will be used, which involves iterative cycles of mathematical modelling and experimental testing. It is made possible by developments made in an earlier funding round in which crucial gene tools and methodologies were developed that will allow precise changes to be made to selected genes and the consequences assessed.