What appear to be biochemical processes may be a natural feature of geology
What appear to be biochemical processes may be a natural feature of geology
看似生化过程的现象，或许是地质学的自然特征
Lifelike biochemistry continued to unfold in sterilized soil for six years, pointing to a metabolic theory for how biology began. 在经过灭菌处理的土壤中，类似生命的生化反应持续了六年之久，这为生命起源的代谢理论提供了线索。
What appear to be biochemical processes may instead be a natural feature of geology. 看似生化过程的现象，实际上可能是地质学的自然特征。
Introduction 引言
For 15 years, Sébastien Fontaine has been trying to kill dirt. The biochemist, who runs a lab at the French National Institute for Agriculture, Food, and Environment, wanted to know how much carbon is released by soil — just dirt alone, completely devoid of life. 15年来，塞巴斯蒂安·方丹（Sébastien Fontaine）一直试图“杀死”土壤。这位在法国国家农业、食品与环境研究院（INRAE）经营实验室的生物化学家，想要弄清楚土壤——仅仅是土壤本身，在完全没有生命的情况下——会释放多少碳。
His team sealed dirt into jars and blasted them with sterilizing gamma radiation. Then they waited for the carbon dioxide released by the soil — a sign of ongoing microbial respiration — to drop. They waited, and waited, and waited some more: weeks, then months. 他的团队将土壤密封在罐子里，并用灭菌的伽马射线进行照射。随后，他们等待土壤释放的二氧化碳（微生物呼吸作用的标志）水平下降。他们等了又等，从几周等到几个月。
Under a microscope, the irradiated soil showed no signs of life, but it continued to emit carbon dioxide. The soil wouldn’t stop breathing. 在显微镜下，受辐射的土壤没有任何生命迹象，但它却持续释放出二氧化碳。土壤似乎“停不下来呼吸”。
Fontaine’s lab repeated the experiments and produced the same results. Finally, convinced that they weren’t dealing with an artifact of the experimental setup, they set out to find the source of breath in dead soil. 方丹的实验室重复了这些实验，结果依然如故。最终，确信这并非实验设置产生的误差后，他们开始着手寻找死土中“呼吸”的来源。
Now, Fontaine and his colleagues have reported that their soil samples continued to consume oxygen and spew carbon dioxide for six years. In a 2025 paper in Science Advances, they proposed that a metabolic process that powers much of life is also possible outside living cells. 现在，方丹及其同事报告称，他们的土壤样本在六年里持续消耗氧气并排放二氧化碳。在2025年发表于《科学进展》（Science Advances）的一篇论文中，他们提出，驱动大多数生命活动的代谢过程在活细胞之外也是可能发生的。
Their experiments point to how it could work in dirt, absent the living proteins that would typically organize it. If they’re right, some biochemical reactions, such as those that release the energy of carbon-rich sugar molecules, may not be unique to living things. 他们的实验指出了这一过程如何在没有通常负责组织它的活性蛋白质的情况下，在土壤中运作。如果他们是正确的，那么某些生化反应（例如释放富碳糖分子能量的反应）可能并非生命体所独有。
Such reactions — known as metabolism when performed by cells — could even predate life on Earth, Fontaine said. 方丹表示，这类反应——当由细胞执行时被称为代谢——甚至可能早于地球上的生命出现。
The experiments show “what happens to biomolecules when they’re left to their own devices,” said Joseph Moran, an organic chemist at the University of Ottawa who was not involved with the research. They’re finding that the chemistry of life is not exclusive to life, he added. “It’s the chemistry of geology.” 渥太华大学的有机化学家约瑟夫·莫兰（Joseph Moran）并未参与这项研究，他评价道，这些实验展示了“生物分子在不受干预时会发生什么”。他补充说，他们发现生命的化学反应并非生命所独有，“这是地质学的化学。”
The Living Dead 活着的死物
When he made this accidental discovery, Fontaine was trying to establish a baseline for carbon in lifeless soil. Using a sterile syringe, the researchers periodically sampled the air in a hermetically sealed jar containing soil and measured its carbon content using a mass spectrometer. 当方丹偶然发现这一现象时，他原本只是想为无生命土壤中的碳含量建立一个基准。研究人员使用无菌注射器，定期对密封罐中的土壤空气进行采样，并利用质谱仪测量其碳含量。
After radiation wiped out the soil microbes, the carbon emission rate declined quickly but didn’t disappear. It remained stable for over 100 days. 在辐射消灭了土壤微生物后，碳排放率迅速下降，但并未消失。它在超过100天的时间里保持稳定。
When he shared the results with other researchers, they advised him to treat it as an experimental artifact — a source of error not worth ferreting out — and move on. But he couldn’t. He needed to understand whether a metabolic process only known to occur in biological cells — a precisely orchestrated sequence of chemical reactions, requiring several molecules and enzymes — was unfolding in sterile soil. 当他与其他研究人员分享这些结果时，他们建议他将其视为实验误差——一种不值得深究的错误来源——并继续进行其他研究。但他无法做到。他必须弄清楚，一种仅已知存在于生物细胞中的代谢过程——即需要多种分子和酶参与、精确协调的化学反应序列——是否正在无菌土壤中发生。
To see what was happening, his team added a dash of enzymes extracted from yeast cultures. Immediately, the soil’s carbon emissions spiked. This, they speculated, was because the enzymes had ramped up a reaction that was already happening. 为了观察发生了什么，他的团队添加了少量从酵母培养物中提取的酶。土壤的碳排放量立即激增。他们推测，这是因为这些酶加速了原本就在进行的反应。
Convincing the scientific community, however, was an uphill battle. When Fontaine submitted the manuscript to journals for publication, some reviewers “were highly positive, and others were really suspicious, especially concerning the sterility of the soil,” he recalled. 然而，要说服科学界是一场艰苦的战斗。方丹回忆说，当他将手稿提交给期刊发表时，一些审稿人“非常积极，而另一些则非常怀疑，特别是对土壤的无菌状态存疑。”
In 2013 the results were published in the journal Biogeosciences. Still, Fontaine could not rest. Bruised by the harsh reviews, he decided to definitively prove that his irradiated soil samples remained free of life. 2013年，研究结果发表在《生物地球科学》（Biogeosciences）杂志上。尽管如此，方丹仍无法释怀。受到严厉评审的打击，他决定彻底证明他受辐射的土壤样本确实没有生命。
Over the following decade, his lab would, in fits and starts, chip away at their obsession. They considered the possibility that the soil wasn’t really dead, and tried to kill it harder with more radiation, pressure, and heat. Still, the soil continued to emit carbon for months. 在接下来的十年里，他的实验室断断续续地钻研着这个令他们着迷的问题。他们考虑了土壤可能并未真正死亡的可能性，并尝试通过更强的辐射、压力和热量来彻底杀死它。然而，土壤依然持续数月排放碳。
Through an electron microscope, Benoit Kéraval, then a graduate student in Fontaine’s lab, found cells in the irradiated soil. But staining showed no RNA or DNA molecules, indicating that the cells were definitely dead. 通过电子显微镜，当时在方丹实验室攻读研究生的伯努瓦·凯拉瓦尔（Benoit Kéraval）在受辐射的土壤中发现了细胞。但染色显示没有RNA或DNA分子，这表明这些细胞确实已经死亡。
When they experimentally added microbes to simulate contamination, the cells rapidly recolonized the soil microcosm and released much more carbon dioxide. So what they were observing in the sterilized sample likely wasn’t a result of inadequate antiseptic measures. 当他们通过实验添加微生物来模拟污染时，这些细胞迅速重新占领了土壤微环境并释放出更多的二氧化碳。因此，他们在灭菌样本中观察到的现象，很可能并非灭菌措施不当所致。
By 2018, when Clémentin Bouquet joined the lab, the team was confident in its findings and ready to dig into the underlying mechanisms. 到2018年克莱芒坦·布凯（Clémentin Bouquet）加入实验室时，团队对研究结果已充满信心，并准备深入挖掘其背后的机制。
Dirty Electrons “肮脏”的电子
For six years, Bouquet and Kéraval studied two sets of sealed, irradiated soil samples — one of normal soil, and one that was supplemented with glucose. For 142 days, they took regular air samples and saw the daily rate of carbon dioxide emissions decline but not disappear, just as they had before. 六年来，布凯和凯拉瓦尔研究了两组密封的受辐射土壤样本——一组是普通土壤，另一组添加了葡萄糖。在142天的时间里，他们定期采集空气样本，观察到每日二氧化碳排放率有所下降但并未消失，正如他们之前所见的那样。
Then the samples sat in an incubator for over 1,000 days, as the researchers focused on their other experiments into how microbes process and store carbon in soil. When they measured the samples again, at days 1,606 and 2,442, the emissions had slowed further, but the soil was still breathing. 随后，这些样本在培养箱中放置了超过1000天，期间研究人员专注于其他关于微生物如何在土壤中处理和储存碳的实验。当他们在第1606天和第2442天再次测量样本时，排放速度进一步减慢，但土壤仍在“呼吸”。
The glucose-augmented samples showed higher emission rates, which strengthened Fontaine’s suspicion that nonbiological catalysts in soil can induce reactions that resemble the metabolic breakdown of sugar. 添加了葡萄糖的样本显示出更高的排放率，这加强了方丹的猜想：土壤中的非生物催化剂可以诱导类似于糖代谢分解的反应。
During metabolism, sugar is broken down into smaller carbon molecules, which feed the Krebs cycle — a series of reactions in which high-energy electrons are stripped from carbon-rich molecules. Electrons liberated by the Krebs cycle then pass through another set of reactions that consume oxygen. For some researchers, it was a stretch to suggest that this process could unfold outside a cell. Fontaine wo 在代谢过程中，糖被分解成更小的碳分子，这些分子进入克雷布斯循环（Krebs cycle）——这是一系列从富碳分子中剥离高能电子的反应。由克雷布斯循环释放的电子随后通过另一组消耗氧气的反应。对于一些研究人员来说，认为这一过程可以在细胞外发生有些牵强。方丹……（注：原文此处中断）