Engineering biobutanol production in a cellulosic clostridium using synthetic biology principles

利用合成生物学原理在纤维素梭菌中工程化生物丁醇生产

• 批准号: BB/G017395/1
• 金额: $ 9.48万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Training Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FG017395%2F1
• 关键词: Engineering; biobutanol; production; cellulosic; clostridium

Currently the fuels we use to provide electricity or to run cars and other vehicles is derived from coal, oil and gas. The availability of these 'fossil fuels,' however, is limited and it is projected that current sources will be exhausted by the middle of the 21st century. Furthermore, it is now apparent that the use of fossil fuels is a major contributor to global warming through the production of carbon dioxide. Thus, there is considerable interest into using more environmentally friendly and renewable systems for producing liquid fuels, now widely referred to as 'biofuels,' for cars and other vehicles. As a consequence there has been widespread adoption of the production of ethanol from plant derived starch using yeast in a fermentation process akin to that used in brewing. Two fundamental improvements to the process would be of benefit. On the one hand, more effective fuels to ethanol could be produced. On the other hand, starch is an important component of the human diet, and as the world population expands and agricultural land diminishes through global warming, it will be impossible to sustain the competition between the use of this polysaccharide for human consumption and biofuel production. The above two improvements would be met by developing a process for the large scale production of the superior biofuel, butanol, and by developing microbes able to convert plant cell derived lignocellulose into biofuel. 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 than ethanol without engine modification, offers better fuel economy than petrol-ethanol blends and has, unlike ethanol, potential to be used as aviation fuel. Lignocellulose, the most abundant source of organic carbon on the planet, is both renewable and does not represent a human food source. The bacteria that produce butanol are called 'solventogenic' and belong to a group called Clostridium, typified by Clostridium acetobutylicum. Although those solventogenic species that can produce butanol are unable to efficiently degrade lignocellulose, there are examples of clostridial species, such as Clostridium thermocellum, that can. This is a consequence of the production of a specialised complex of enzymes called the 'cellulosome', one of the most efficient plant cell wall degrading systems known. Cellulosome-producing bacteria do not, however, produce butanol, only ethanol. Using proprietary, patented technology developed at Nottingham, and drawing on knowledge gained from a current BBSRC project concerned with metabolic engineering of the butanol pathway in C. acetobutylicum, we will take the genes which encode the butanol pathway, and introduce them into C. thermocellum using synthetic biology principles. The ability of the engineered bacterium to degrade plant cell walls and ferment the sugars generated into butanol will be evaluated. The net result will be the creation of more environmentally friendly, sustainable processes for second generation biofuel production.

目前，我们用于提供电力或运行汽车和其他车辆的燃料来自煤炭、石油和天然气。然而，这些“化石燃料”的可用性是有限的，预计现有资源将在 21 世纪中叶耗尽。此外，现在很明显，化石燃料的使用通过产生二氧化碳而成为全球变暖的主要原因。因此，人们对使用更加环保和可再生的系统来生产用于汽车和其他车辆的液体燃料（现在被广泛称为“生物燃料”）产生了很大的兴趣。因此，人们广泛采用在类似于酿造过程的发酵过程中使用酵母从植物源淀粉生产乙醇。该流程的两项根本性改进将是有益的。一方面，可以生产更有效的乙醇燃料。另一方面，淀粉是人类饮食的重要组成部分，随着全球变暖导致世界人口增长和农业用地减少，这种用于人类消费的多糖与生物燃料生产之间的竞争将不可能持续下去。上述两项改进将通过开发大规模生产优质生物燃料丁醇的工艺以及开发能够将植物细胞衍生的木质纤维素转化为生物燃料的微生物来实现。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，可以在不改造发动机的情况下以比乙醇更高的浓度与汽油混合，比汽油-乙醇混合物提供更好的燃油经济性，并且与乙醇不同，具有用作航空燃料的潜力。木质纤维素是地球上最丰富的有机碳来源，既是可再生的，也不代表人类的食物来源。产生丁醇的细菌被称为“产溶剂”，属于梭状芽胞杆菌属，以丙酮丁醇梭状芽胞杆菌为代表。尽管那些能够产生丁醇的产溶剂物种无法有效降解木质纤维素，但有梭菌物种的例子，例如热纤梭菌，可以。这是一种称为“纤维素体”的特殊酶复合物产生的结果，“纤维素体”是已知的最有效的植物细胞壁降解系统之一。然而，产生纤维素体的细菌不产生丁醇，仅产生乙醇。利用诺丁汉开发的专有技术，并利用当前 BBSRC 项目中获得的知识，该项目涉及丙酮丁醇梭菌中丁醇途径的代谢工程，我们将采用编码丁醇途径的基因，并利用合成生物学原理将其引入热纤梭菌中。将评估工程细菌降解植物细胞壁并将产生的糖发酵成丁醇的能力。最终结果将是为第二代生物燃料生产创造更加环保、可持续的工艺。