I'm an ocean microbiologist at the University of Tennessee, and I want to tell you guys about some microbes that are so strange and wonderful that they're challenging our assumptions about what life is like on Earth.
我是田纳西大学的 一位海洋微生物科学家, 我想告诉大家,有一些微生物 非常的奇特与美妙, 它们挑战着 我们对地球上生命的认知。
So I have a question. Please raise your hand if you've ever thought it would be cool to go to the bottom of the ocean in a submarine? Yes. Most of you, because the oceans are so cool.
我想问大家一个问题。 如果你曾经觉得坐潜水艇去海底 很酷的话,请举起你的手。 很好。 大部分人都举了手, 因为海洋真的很酷!
Alright, now -- please raise your hand if the reason you raised your hand to go to the bottom of the ocean is because it would get you a little bit closer to that exciting mud that's down there.
好的,那如果 你想去海底的原因是 这会让你更加接近 海底令人激动人心的泥, 请举起你的手。
(Laughter)
(笑声)
Nobody. I'm the only one in this room.
没人啊! 我是这个屋子里的唯一一个。
Well, I think about this all the time. I spend most of my waking hours trying to determine how deep we can go into the Earth and still find something, anything, that's alive, because we still don't know the answer to this very basic question about life on Earth.
好的,我总是在想, 我每天醒来后的大部分时间 都花在决定我们可以 探入地球多深这件事上, 并且还会发现有一些活着的生命, 因为我们还是不知道 关于地球上的生命这个 最基本问题的答案。
So in the 1980s, a scientist named John Parkes, in the UK, was similarly obsessed, and he came up with a crazy idea. He believed that there was a vast, deep, and living microbial biosphere underneath all the world's oceans that extends hundreds of meters into the seafloor, which is cool, but the only problem is that nobody believed him, and the reason that nobody believed him is that ocean sediments may be the most boring place on Earth.
在上世纪80年代,一位叫做 约翰·派克斯的英国科学家, 也同样沉迷于这个问题, 他想出了一个疯狂的点子。 他相信在全世界的海洋底部 都有一个巨大,深邃,生机勃勃的 微生物圈, 深入海床达几百米, 听起来很酷, 可是唯一的问题是,没人相信他, 而其背后的原因是 海洋的沉积处可能是 地球上最枯燥乏味的地方了。
(Laughter)
(笑声)
There's no sunlight, there's no oxygen, and perhaps worst of all, there's no fresh food deliveries for literally millions of years. You don't have to have a PhD in biology to know that that is a bad place to go looking for life.
那里没有阳光,没有氧气, 可能最坏的情况是, 那里没有新鲜的食物供给 已经持续长达几百万年。 你不需要一个生物学博士学位 就会知道那里不是一个 寻找生命的好地方。
(Laughter)
(笑声)
But in 2002, [Steven D'Hondt] had convinced enough people that he was on to something that he actually got an expedition on this drillship, called the JOIDES Resolution. And he ran it along with Bo Barker Jørgensen of Denmark. And so they were finally able to get good pristine deep subsurface samples some really without contamination from surface microbes. This drill ship is capable of drilling thousands of meters underneath the ocean, and the mud comes up in sequential cores, one after the other -- long, long cores that look like this. This is being carried by scientists such as myself who go on these ships, and we process the cores on the ships and then we send them home to our home laboratories for further study.
但是在2002年, 约翰说服了足够多的人 相信他会有新发现, 于是他得到了一个在一艘叫做 乔伊斯决心号的 钻探船上考察的机会。 他和来自丹麦的波巴克·约金森 一同进行了那次考察。 他们终于可以拿到 真正的深海下表层的样本, 没有接触到任何 表层微生物的污染。 这艘钻探船可以钻进海底几千米, 泥被储存在一个接一个的 管子里按顺序被打上来, 就像这样长长的管子。 然后由像我这样 在船上的科学家拿着, 在船上处理重要的部分, 然后把它们送回 实验室,再进行更深入的研究。
So when John and his colleagues got these first precious deep-sea pristine samples, they put them under the microscope, and they saw images that looked pretty much like this, which is actually taken from a more recent expedition by my PhD student, Joy Buongiorno. You can see the hazy stuff in the background. That's mud. That's deep-sea ocean mud, and the bright green dots stained with the green fluorescent dye are real, living microbes.
当约翰和他的同事们 初次拿到了这些宝贵, 新鲜干净的深海样本时, 他们把样本放在了显微镜下, 并看到了像这样的图片, 这其实是最近一次考察拿来的样本, 数据来自我的博士学生, Joy Buongiorno。 你们可以看到背景有些雾蒙蒙的东西。 那是泥,深海泥, 亮亮的绿点,被绿色荧光染色的 是真的,活着的微生物。
Now I've got to tell you something really tragic about microbes. They all look the same under a microscope, I mean, to a first approximation. You can take the most fascinating organisms in the world, like a microbe that literally breathes uranium, and another one that makes rocket fuel, mix them up with some ocean mud, put them underneath a microscope, and they're just little dots. It's really annoying. So we can't use their looks to tell them apart. We have to use DNA, like a fingerprint, to say who is who.
现在我需要告诉你们 微生物真正悲剧的地方。 它们在显微镜下看起来都一样。 我是说,初次预测的时候。 你可以拿着世界上 最迷人的有机组织, 比如说一个可以呼吸铀的微生物, 和一个可以产生火箭燃料的微生物, 把它们和一些深海泥混在一起, 然后把它们放在显微镜下观察。 它们只会是一个个小点点, 很让人抓狂。 所以我们不能通过 它们的样子来辨别它们。 我们需要用DNA, 像指纹一样 来分清谁是谁。
And I'll teach you guys how to do it right now. So I made up some data, and I'm going to show you some data that are not real. This is to illustrate what it would look like if a bunch of species were not related to each other at all. So you can see each species has a list of combinations of A, G, C and T, which are the four sub-units of DNA, sort of randomly jumbled, and nothing looks like anything else, and these species are totally unrelated to each other. But this is what real DNA looks like, from a gene that these species happen to share. Everything lines up nearly perfectly. The chances of getting so many of those vertical columns where every species has a C or every species has a T, by random chance, are infinitesimal. So we know that all those species had to have had a common ancestor. They're all relatives of each other.
我现在来教你们怎么做。 我编了一些数据, 我要给大家展示这些模拟数据。 只是为了展示如果 一群物种彼此之间毫无联系, 数据看起来应该是什么样子。 你可以看到每个物种 有一系列由A, G, C, T组成的组合, 这些是DNA的四个碱基对, 几乎是随机地乱成一团, 彼此看起来毫无相似之处, 这些物种彼此之间毫无关联。 但这是真正的DNA, 这些物种共享的基因。 所有碱基都完美的排列着。 得到这些竖着的列的概率 比如每个物种在这列都有个c, 或者在这列都有个t的 随机概率是无穷小的。 我们了解到所有的物种 是需要有一个共同的祖先的。 它们彼此都是亲戚。
So now I'll tell you who they are. The top two are us and chimpanzees, which y'all already knew were related, because, I mean, obviously.
现在我来告诉大家它们到底是谁。 最上边的两个是人类和大猩猩, 我们都知道了这两个物种 是有关联的,这很明显吧。
(Laughter)
(笑声)
But we're also related to things that we don't look like, like pine trees and Giardia, which is that gastrointestinal disease you can get if you don't filter your water while you're hiking. We're also related to bacteria like E. coli and Clostridium difficile, which is a horrible, opportunistic pathogen that kills lots of people. But there's of course good microbes too, like Dehalococcoides ethenogenes, which cleans up our industrial waste for us. So if I take these DNA sequences, and then I use them, the similarities and differences between them, to make a family tree for all of us so you can see who is closely related, then this is what it looks like. So you can see clearly, at a glance, that things like us and Giardia and bunnies and pine trees are all, like, siblings, and then the bacteria are like our ancient cousins. But we're kin to every living thing on Earth. So in my job, on a daily basis, I get to produce scientific evidence against existential loneliness.
但是我们也和很多跟我们 不相像的物种有联系, 比如,松树、贾第虫, 一种肠胃疾病, 如果你徒步时在山上喝了没有经过 过滤的水的话,可能会得这种病。 我们与大肠杆菌和 艰难梭菌也有联系, 艰难梭菌是一种特别不好的 爱钻空子的病原体,杀死了很多的人。 但也有很多对我们有益的微生物, 比如产乙烯脱卤拟球菌, 它们可以帮助我们清洁工业废物。 如果我用这些DNA序列, 用它们的相同和不同之处 做一个家谱的话, 你可以看到谁跟谁联系更紧密, 它们看起来是这样的。 你可以清楚的看出来, 我们人类和贾第虫,兔子,还有松树 都像是亲兄弟姐妹, 细菌则像我们的远古表亲。 但我们跟地球上的 生物都有亲戚关系。 我每天的工作就是, 提供科学证据来 反驳我们是孤独存在着的物种。
So when we got these first DNA sequences, from the first cruise, of pristine samples from the deep subsurface, we wanted to know where they were. So the first thing that we discovered is that they were not aliens, because we could get their DNA to line up with everything else on Earth. But now check out where they go on our tree of life. The first thing you'll notice is that there's a lot of them. It wasn't just one little species that managed to live in this horrible place. It's kind of a lot of things. And the second thing that you'll notice, hopefully, is that they're not like anything we've ever seen before. They are as different from each other as they are from anything that we've known before as we are from pine trees. So John Parkes was completely correct. He, and we, had discovered a completely new and highly diverse microbial ecosystem on Earth that no one even knew existed before the 1980s.
所以当我们在第一艘钻探船上拿到 深海底部样品的第一个DNA序列时, 我们想知道它们位于 这个家谱上的什么位置。 我们发现的第一件事是, 它们不是外星人, 它们的DNA可以跟地球上的 其他生物排在一起。 但是看它们在这个家谱上的位置。 你们首先会注意到的是, 它们有很多种类, 不是一个小小的物种 存活在恶劣的环境下。 而是很多东西并存。 你们也许会注意到的第二点就是, 它们与我们之前见过的 东西一点儿都不像。 它们彼此也大不相同, 就像和我们已知的物种很不同一样, 就像我们跟松树的不同。 所以约翰·帕克思是完全正确的。 他,和我们,发现了一个 崭新并高度多样化的 地球微生物圈, 而在80年代以前没人知道它的存在。
So now we were on a roll. The next step was to grow these exotic species in a petri dish so that we could do real experiments on them like microbiologists are supposed to do. But no matter what we fed them, they refused to grow. Even now, 15 years and many expeditions later, no human has ever gotten a single one of these exotic deep subsurface microbes to grow in a petri dish. And it's not for lack of trying. That may sound disappointing, but I actually find it exhilarating, because it means there are so many tantalizing unknowns to work on. Like, my colleagues and I got what we thought was a really great idea. We were going to read their genes like a recipe book, find out what it was they wanted to eat and put it in their petri dishes, and then they would grow and be happy. But when we looked at their genes, it turns out that what they wanted to eat was the food we were already feeding them. So that was a total wash. There was something else that they wanted in their petri dishes that we were just not giving them.
现在我们手气正旺, 下一步是在培养基上 培养这些奇异的物种, 这样就可以用它们 做真正的科学实验, 做微生物学家该做的工作。 可是不管我们喂给它们什么, 它们都不成长。 甚至在15年后的现在, 经历了许多科学考察之后。 仍然没有人可以让 那些来自深海的微生物 在培养基上长大。 这不是因为缺乏尝试。 这也许听起来很令人失望, 但我却觉得这令人振奋, 因为这意味着有许许多多 未知有待发掘。 比如,我和同事 想出了一个特别好的点子。 我们打算像读菜谱一样 读取它们的基因, 发现它们想吃什么, 然后放在培养基上, 这样它们就会快乐地长大。 但是当我们检查它们基因的时候, 发现它们想吃的食物 我们已经在喂了。 所以那个点子就废了。 就是说,在培养基上, 它们想要的其他东西 我们并没有提供。
So by combining measurements from many different places around the world, my colleagues at the University of Southern California, Doug LaRowe and Jan Amend, were able to calculate that each one of these deep-sea microbial cells requires only one zeptowatt of power, and before you get your phones out, a zepto is 10 to the minus 21, because I know I would want to look that up. Humans, on the other hand, require about 100 watts of power. So 100 watts is basically if you take a pineapple and drop it from about waist height to the ground 881,632 times a day. If you did that and then linked it up to a turbine, that would create enough power to make me happen for a day. A zeptowatt, if you put it in similar terms, is if you take just one grain of salt and then you imagine a tiny, tiny, little ball that is one thousandth of the mass of that one grain of salt and then you drop it one nanometer, which is a hundred times smaller than the wavelength of visible light, once per day. That's all it takes to make these microbes live. That's less energy than we ever thought would be capable of supporting life, but somehow, amazingly, beautifully, it's enough.
把从世界不同地方的测量数据 结合到一起时, 我在南加州大学的同事们 Doug LaRowe和Jan Amend, 成功计算出了每个深海微生物 只需要一仄普托(zepto)瓦的能量, 别忙着掏手机, 一个仄普托是10的负21次方。 要是我肯定是会查一下的。 另一方面,人类 需要100瓦的能量。 100瓦是你拿一个菠萝, 然后每天从你腰部那么高的地方 丢到地上88万1632次。 如果你连上一个涡轮 这么做了的话, 你就可以创造足够支撑我 一整天的能量。 一仄普托瓦,用一个类似的比较, 如果你拿一粒盐做参照物, 然后你想象一个很小很小很小的球, 大约是一粒盐重量的1/1000, 然后你把它丢下1纳米的高度, 一纳米大约是 可见光波长的1/100的长度, 每天丢一次。 这就是这些微生物存活需要的能量。 比我们之前想的 可以支撑生命的能量要少很多, 但是让人惊讶,却十分美妙的是, 这就够了。
So if these deep-subsurface microbes have a very different relationship with energy than we previously thought, then it follows that they'll have to have a different relationship with time as well, because when you live on such tiny energy gradients, rapid growth is impossible. If these things wanted to colonize our throats and make us sick, they would get muscled out by fast-growing streptococcus before they could even initiate cell division. So that's why we never find them in our throats. Perhaps the fact that the deep subsurface is so boring is actually an asset to these microbes. They never get washed out by a storm. They never get overgrown by weeds. All they have to do is exist. Maybe that thing that we were missing in our petri dishes was not food at all. Maybe it wasn't a chemical. Maybe the thing that they really want, the nutrient that they want, is time. But time is the one thing that I'll never be able to give them. So even if I have a cell culture that I pass to my PhD students, who pass it to their PhD students, and so on, we'd have to do that for thousands of years in order to mimic the exact conditions of the deep subsurface, all without growing any contaminants. It's just not possible. But maybe in a way we already have grown them in our petri dishes. Maybe they looked at all that food we offered them and said, "Thanks, I'm going to speed up so much that I'm going to make a new cell next century. Ugh.
如果这些海洋底部下的微生物 跟能量之间有一个与我们之前 假设的不一样的关系, 那么接下来就是它们需要 与时间之间也有不同的关系, 因为如果你靠着 这么微小的能量生活, 快速成长是不可能的。 如果这些微生物想占领我们的喉咙 然后让我们生病, 它们会在第一次分裂发生前 被快速繁殖的链球菌踢出局。 所以我们不会在喉咙里找到它们。 也许深海的下表层 极度无聊的环境 其实是对这些微生物 来说是一种财富。 它们不会被一场风暴冲刷走。 它们不会被海草覆盖。 它们要做的就是存在着。 也许我们在培养基上缺少的 根本不是食物。 也许都不是任何化学物质。 也许它们真正想要的, 它们想要的营养是,时间。 但是时间是唯一 我没法给它们的东西。 即使我有一个细胞群可以 传给我的博士生, 然后他们会传给他们的 博士生,如此延续, 都需要传上个几千年 才能模仿出深海的环境, 这还是在无任何污染的情况下。 这是完全不可能做到的。 但也许我们已经在我们的 培养基上繁殖它们了。 也许它们看看我们给的食物说, “谢谢,我决定加速繁殖, 要在下个世纪分裂一个新细胞。” 唉.....
(Laughter)
(笑声)
So why is it that the rest of biology moves so fast? Why does a cell die after a day and a human dies after only a hundred years? These seem like really arbitrarily short limits when you think about the total amount of time in the universe. But these are not arbitrary limits. They're dictated by one simple thing, and that thing is the Sun. Once life figured out how to harness the energy of the Sun through photosynthesis, we all had to speed up and get on day and night cycles. In that way, the Sun gave us both a reason to be fast and the fuel to do it. You can view most of life on Earth like a circulatory system, and the Sun is our beating heart.
那为什么其他的生物动作那么快? 为什么一个细胞一天就死亡了, 一个人在一百年后就会死亡? 当你想到宇宙中的时间总和, 这些看起来就都是 很短的随机限制了。 但这些并不是毫无规律的限制。 它们被一个东西主宰着, 那就是太阳。 当生命弄清怎么通过光合作用 从太阳获取能量, 我们不得不加速, 然后适应白日黑夜的轮回。 在这个意义上,太阳给了 我们一个加速的理由, 也给了我们加速的原料。 你可以把地球上大多数生命 看成一个循环系统, 太阳就是我们跳动着的心脏。
But the deep subsurface is like a circulatory system that's completely disconnected from the Sun. It's instead being driven by long, slow geological rhythms. There's currently no theoretical limit on the lifespan of one single cell. As long as there is at least a tiny energy gradient to exploit, theoretically, a single cell could live for hundreds of thousands of years or more, simply by replacing broken parts over time. To ask a microbe that lives like that to grow in our petri dishes is to ask them to adapt to our frenetic, Sun-centric, fast way of living, and maybe they've got better things to do than that.
而深海下表层也像一个 与太阳完全隔离的 循环系统。 它的演变在被漫长的地质韵律驱使。 一个单细胞的生命长度 目前还没有理论上的限制。 只要有一丁点儿的能量可以用, 理论上讲,一个细胞可以存活 几十万年甚至更久, 必要时换掉坏的部件就可以了。 让一个微生物在我们的培养皿中 那样存活,就等于是在 要求它们来适应我们疯狂的 以太阳为中心的快速生活方式, 也许它们有其他 更重要的事情要做呢。
(Laughter)
(笑声)
Imagine if we could figure out how they managed to do this. What if it involves some cool, ultra-stable compounds that we could use to increase the shelf life in biomedical or industrial applications? Or maybe if we figure out the mechanism that they use to grow so extraordinarily slowly, we could mimic it in cancer cells and slow runaway cell division. I don't know. I mean, honestly, that is all speculation, but the only thing I know for certain is that there are a hundred billion billion billlion living microbial cells underlying all the world's oceans. That's 200 times more than the total biomass of humans on this planet. And those microbes have a fundamentally different relationship with time and energy than we do. What seems like a day to them might be a thousand years to us. They don't care about the Sun, and they don't care about growing fast, and they probably don't give a damn about my petri dishes ...
想象一下,如果我们可以 弄清它们怎么做到的。 如果这其中包含着某些 特别酷,特别稳定的化合物 可以被利用来提高生物医药产品和 工业产品的有效期,会怎么样? 或许我们可以研究出它们之所以可以 成长得如此缓慢的机制, 那我们就可以在癌细胞中 模拟这个机制,从而减缓癌细胞的分裂。 我也不知道。 那些都只是我的猜测, 但是我唯一可以确定的是, 有着数目无法估量的 活着的微生物细胞 待在全世界海洋的底部。 相当于地球上全部人类生物质 总和的200多倍。 从本质上说,比起人类, 那些微生物与时间和能量 有着不同的关系。 它们世界中的一天 可能对我们而言像是几千年。 它们才不管太阳呢, 也不屑于快速的繁殖, 它们可能也不在意 呆在我的培养皿里...
(Laughter)
(笑声)
but if we can continue to find creative ways to study them, then maybe we'll finally figure out what life, all of life, is like on Earth.
但是如果我们继续去 发现新的方法来研究它们, 那么也许我们最终可以 搞清楚地球上全部的生命。
Thank you.
谢谢大家。
(Applause)
(鼓掌)