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

到2030年，全球能源消耗预计将增长57%。化石燃料不能满足这一需求，因为它们的继续使用正在导致全球变暖，而且无论如何是有限的储备，将在本世纪结束之前耗尽。来自天然植物材料的液体燃料（生物燃料）是运输部门最有前途的替代能源。在这方面，一种称为丁醇的醇由于其与乙醇和生物柴油相比的上级性质而目前受到相当大的关注。丁醇的能量含量比乙醇高，可以利用现有的汽油供应和分销渠道，可以在更高的浓度下与汽油混合，而无需对发动机进行改造，具有更好的燃料经济性，并且与乙醇不同，具有作为航空燃料的潜力。传统上，丁醇是由一种叫做丙酮丁醇梭菌的细菌在含有糖的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。在上个世纪上半叶，ABE工艺在重要性/规模上仅次于从酵母生产乙醇。然而，随着石化工业的出现，这一过程变得不经济，并从20世纪60年代起在西方世界被遗弃。该工艺最近在中国和巴西重新建立，在那里较低的操作成本使得基于低效的20世纪技术的工艺变得经济。为了在西方世界采用，需要一个更有效的过程。其衍生将依赖于对所用细菌菌株的改进。然而，这种菌株的合理创造将需要更详细地了解细胞内催化和控制发酵产物形成的复杂过程。更好地了解这一进程是本提案的总体目标。为此，将使用一种称为系统生物学的新的整体方法，其中涉及数学建模和实验测试的迭代周期。这是由于在较早的一轮供资中取得的进展，其中开发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，并评估其后果。

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.