题记：微生物本身就像是一个化工厂，因为某些种类的细菌会发酵二氧化碳(CO2) 气体来选择它们自己的营养物质。 科学家设计了一种加速某些细菌种类中二氧化碳发酵的途径；由此产生的分子：乙酰辅酶A，具有两个独特的碳手柄（C2），可用于制造一系列重要的商品燃料和化学品。细菌已经很厉害了！科学家们又赋予它们新的神奇工具，可谓是如虎添翼了。重工业每年释放数百万吨二氧化碳，这是提炼生物燃料、炼钢或搅拌混凝土的副产品。 科学家们正在探索在二氧化碳到达大气层之前捕获和储存，最好还是使用二氧化碳的技术。气体发酵细菌实际上可以固定二氧化碳，并代表了一种满足我们能源和环境需求的负碳方式。

Not Just Bread and Beer: Microbes Can Ferment Carbon Dioxide To Make Fuel

不仅仅是面包和啤酒：微生物还可以发酵二氧化碳来制造燃料

Bicyclic Carbon Fixation—NREL scientists have designed a pathway for speeding up CO2 fermentation in some species of bacteria. The resulting molecule—acetyl-CoA, with its two unique carbon handles (C2)—can be used to make a range of important commodity fuels and chemicals. Credit: Figure by Besiki Kazaishvili, NREL
双环碳固定——NREL 科学家设计了一种加速某些细菌种类中二氧化碳发酵的途径。 由此产生的分子：乙酰辅酶A，具有两个独特的碳手柄（C2），可用于制造一系列重要的商品燃料和化学品。图片来源：NREL 的 Besiki Kazaishvili
Scientists Mapped Out a “Bicyclic Carbon Fixation” Pathway for Speeding Up Gas Fermentation in Specialized Bacteria
科学家们绘制了一种“双环碳固定”路径，以加速特殊细菌的气体发酵
Bakers ferment the dough for a well-risen loaf of bread. Likewise, brewers ferment wheat and barley for a smooth, malty glass of beer. And as nature’s foremost bakers and brewers, some microbes can do even more. In fact, certain species of bacteria ferment carbon dioxide (CO2) gas to make their own nutrients of choice. This could be leveraged to help energize our world.
面包师将面团发酵成隆起的面包。同样，酿酒商发酵小麦和大麦来制作一杯丝滑的麦芽啤酒。 作为自然界最重要的面包师和酿酒师，一些微生物可以做得更多。 事实上，某些种类的细菌会发酵二氧化碳 (CO2) 气体来选择它们自己的营养物质。 这可以用来帮助激发我们的世界。
This extraordinary ability—fermenting CO2 into chemical energy—is not lost on scientists who study the nuanced and complex chemical reactions in bacteria.
研究细菌中微妙而复杂的化学反应的科学家们并没有失去这种非凡的能力---将二氧化碳发酵成化学能。
Among them is National Renewable Energy Laboratory (NREL) researcher Wei Xiong, who said that gas-fermenting bacteria offer lessons on turning waste gases like CO2 into sustainable fuels.
其中包括国家可再生能源实验室（NREL）研究员熊伟，他说气体发酵细菌为将二氧化碳等废气转化为可持续燃料提供了经验。
“CO2 removal and conversion are of worldwide interest as CO2 is the most important heat-trapping (greenhouse) gas in the atmosphere. Pathways for CO2 fixation are a crux,” Xiong explained. “We have a special interest in designing new CO2 fixation avenues in bacteria to help them synthesize key biofuel precursors, for example, acetyl-CoA.”
“二氧化碳的去除和转化引起了全世界的关注，因为二氧化碳是大气中最重要的吸热（温室）气体。 固定二氧化碳的途径是一个关键，”熊解释说。 “我们对在细菌中设计新的二氧化碳固定路径特别感兴趣，以帮助它们合成关键的生物燃料前体，例如乙酰辅酶A。”
Acetyl-CoA is the main ingredient for making multiple fuel chemicals, including fatty acids, isopropanol, and butanol. And as detailed in a paper that was recently published in the journal NATURE SYNTHESIS, Xiong and his colleagues have shown how to improve the production of the fuel precursor using a novel pathway in gas-fermenting bacteria.
乙酰辅酶 A 是制造多种燃料化学品的主要成分，包括脂肪酸、异丙醇和丁醇。 正如最近发表在《自然合成》杂志上的一篇论文中所详述的，熊和他的同事已经展示了如何使用气体发酵细菌中的一种新途径来改善燃料前体的生产。”
By doing so, they brighten the possibility of using biological methods to capture and convert CO2 at the industrial scale.
通过这样做，他们增加了使用生物方法在工业规模上捕获和转化二氧化碳的可能性。
SIMPLE CARBON ACCOUNTING: C1 + C1 = C2
Naturally, gas-fermentation in bacteria follows a linear series of reactions, known to scientists as the Wood-Ljungdahl pathway. This was named after Professors Harland G. Wood and Lars G. Ljungdahl who discovered it in the 1980s. In simple terms, enzymes strip CO2 of its carbon using the electrical energy from nearby hydrogen or carbon monoxide gas. They then affix two of these one-carbon atoms (C1) onto a larger molecule already present in the bacteria, called coenzyme A (CoA). By attaching two carbon handles (C2) to this helper molecule, they become more easily accessible for other reactions.
简单的碳核算
自然地，细菌中的气体发酵遵循一系列线性反应，科学家们将其称为 Wood-Ljungdahl 途径。 它以 1980 年代发现它的 Harland G. Wood 和 Lars G. Ljungdahl 教授的名字命名。 简单来说，酶利用附近氢气或一氧化碳气体的电能去除二氧化碳中的碳。 然后，他们将其中两个单碳原子 (C1) 附加到细菌中已经存在的更大分子上，称为辅酶 A (CoA)。 通过将两个碳手柄 (C2) 连接到这个辅助分子上，它们变得更容易进行其他反应。
The final result? Acetyl-CoA, a more energy- and carbon-dense molecule that supports the bacteria’s growth. It is also a handy precursor for making valuable, climate-friendly biofuels.
最后的结果？ 乙酰辅酶A，一种支持细菌生长的能量且碳密度更高的分子。 它也是制造有价值的气候友好型生物燃料的便捷前体。
However, despite its cleverness, the Wood-Ljungdahl pathway alone might not be enough for industrial use. Plus, its seemingly simple math (C1 + C1 = C2) is actually the consequence of a dizzying number of chemical reactions.
然而，尽管它很聪明，但仅靠 Wood-Ljungdahl 路径可能不足以用于工业。 此外，它看似简单的数学运算（C1 + C1 = C2）实际上是令人眼花缭乱的化学反应的结果。
“Engineering this pathway to improve efficiency is challenging because of the enzymes’ complexity,” Xiong explained.
“由于酶的复杂性，设计这条提高效率的路径具有挑战性，”熊解释说。
To sidestep improving the Wood-Ljungdahl pathway directly, the researchers set out to conceptualize a completely new pathway for making acetyl-CoA. Using an NREL-developed computer model called PathParser—and state-of-the-art genetic tools—the team invented a new CO2-fixing pathway in a species of gas-fermenting bacteria called CLOSTRIDIUM LJUNGDAHLII.
为了避免直接改进 Wood-Ljungdahl 途径，研究人员着手构思一种全新的制造乙酰辅酶 A 的途径。 使用 NREL 开发的名为 PathParser 的计算机模型和最先进的遗传工具，该团队在一种名为 CLOSTRIDIUM LJUNGDAHLII 的气体发酵细菌中发明了一种新的二氧化碳固定途径。
In the end, the math works out the same: C1 + C1 = C2.
But to get there, it incorporates a pair of parallel reactions—a carbon-fixing bicycle with two wheels working together to capture CO2, transform it using a series of chemical gears, and redirect it to propel acetyl-CoA generation forward (illustrated in the figure at the top of the page). If added to gas-fermenting bacteria, the pathway could complement the Wood-Ljungdahl pathway to more efficiently yield acetyl-CoA.
最后，数学结果是一样的：C1 + C1 = C2。
但为了做到这一点，它包含了一对平行反应：一辆有两个轮子的碳固定自行车一起捕获二氧化碳，使用一系列化学齿轮对其进行转换，并重新定向以推动乙酰辅酶a向前生成（如页面顶部的图所示）。如果添加到气体发酵细菌中，该途径可以补充木-容达尔途径，从而更有效地产生乙酰辅酶a。
CAN WE FERMENT OUR WAY TO CARBON-NEUTRALITY?
There is no shortage of waste gases today, and this is likely to remain true well into the future. Millions of tons of CO2 are released every year by heavy industry—a byproduct of refining biofuels, making steel, or mixing concrete. Scientists are exploring technologies for capturing and storing—better still USING—CO2 well before it ever reaches the atmosphere.
我们能否通过发酵方式实现碳中和？
今天不乏废气，而且很可能在未来很长一段时间内仍然如此。重工业每年释放数百万吨二氧化碳，这是提炼生物燃料、炼钢或搅拌混凝土的副产品。 科学家们正在探索在二氧化碳到达大气层之前捕获和储存，最好还是使用二氧化碳的技术。
“In the context of global warming and climate change, scientists seek new solutions from microbial metabolism for converting CO2 to fuels and chemicals,” Xiong said. “Gas-fermenting bacteria actually fix CO2 and represent a carbon-negative way for meeting our energy and environmental demands.”
“在全球变暖和气候变化的背景下，科学家们从微生物代谢中寻求新的解决方案，将二氧化碳转化为燃料和化学品，”熊说。 “气体发酵细菌实际上可以固定二氧化碳，并代表了一种满足我们能源和环境需求的负碳方式。”
Who better to learn from than gas-fermenting bacteria that have fixed CO2 with ease for millions of years?
有谁能比那些能轻松固定二氧化碳数百万年的气体发酵细菌，是更好的学习对象呢？