Understanding and harnessing the hydrogen-dependent carbon dioxide reductase activity of E. coli.

为了一个可持续的未来，科学家面临的一个挑战是想出创新和鼓舞人心的新想法来处理废物和鼓励回收利用。从农业垃圾，到食物垃圾和包装，一直到大规模的工业污染，来自各个专业领域的科学家都可以在寻找可持续解决方案方面发挥作用。能源工业、运输部门和其他重工业(如钢铁、混凝土)产生的气态二氧化碳是一种众所周知的、对环境重要的废气。减少二氧化碳排放将需要一篮子不同的解决方案，而生物学提供了一些令人兴奋的选择。微小的单细胞细菌习惯于生活在极端环境中，经常进行植物和动物无法进行的生化反应。例如，通常无害的肠道细菌大肠杆菌可以在完全没有氧气的情况下生长。当它这样做时，它会消化糖，并产生二氧化碳和氢气作为气态产品。我们灵机一动，或许可以让这种反应倒退。果然，当大肠杆菌被置于二氧化碳和氢气气氛中，并施加一定的压力时，细菌就会吸收二氧化碳并将其转化为其他东西。另一种东西是甲酸，这一发现可能是生物技术的一项重要突破。我们现在可以在生长中的活细胞中更详细地研究二氧化碳转化为甲酸的过程，并对其进行优化，使其主要在一个方向上发挥作用，即“依赖氢气的二氧化碳还原酶”。我们还可以考虑甲酸的用途--例如，也许可以使用进一步适应的细菌来制造甲醇或乳酸，我们可以解决使这一新发现对广泛行业有用的一些关键障碍。最终，支撑科学和由此产生的应用生物技术有可能帮助减少各种来源的二氧化碳排放，并将二氧化碳废物转化为更有用的产品。这种新的生物技术有朝一日将为真正的循环生物经济做出贡献，在这种经济中，废物流最少。

For a sustainable future one challenge to scientists is to think of innovative and inspiring new ideas to tackle waste and encourage recycling. From agricultural waste, to food waste and packaging, and all the way to large-scale industrial pollution, scientists from all areas of expertise have a part to play in finding sustainable solutions.Gaseous carbon dioxide produced by the energy industry, transport sector and other heavy industries (e.g. steel, concrete) is a well-known and environmentally important waste gas. Reducing carbon dioxide emissions will require a basket of different solutions and biology offers some exciting options. Microscopic, single-celled bacteria are used to living in extreme environments and often perform biochemical reactions that plants and animals cannot do. The usually harmless gut bacterium Escherichia coli, for example, can grow in the complete absence of oxygen. When it does this it digests sugars and produces carbon dioxide and hydrogen as gaseous products. We had a brainwave that we might be able to get this reaction to run backwards instead. Sure enough, when E. coli is placed under a CO2 and H2 atmosphere, and some pressure is applied, then the bacterium takes up the CO2 and converts it into something else. That something else is formic acid and this finding is potentially an important breakthrough for biotechnology. We can now examine the conversion of CO2 to formic acid in more detail in growing, living cells, and optimise it to work mainly in one direction as a 'hydrogen-dependent CO2 reductase'. We can also think about what the formic acid could be used for - maybe to make methanol or lactate using further adapted bacteria, for example, and we can address some of the key obstacles to making this new discovery useful to a wide range of industries.Ultimately, the underpinning science, and the applied biotechnology that results, has the potential to help reduce carbon dioxide emissions from a whole range of sources, and to convert that CO2 waste into more useful products. This new biotechnology will one day contribute to a truly circular bioeconomy where waste streams are minimal.