The tiny creature that secretly powers the planet | Penny Chisholm

翻译人员: jacks peng 校对人员: Yolanda Zhang

I'd like to introduce you to a tiny microorganism

我想向你们介绍一种小小的微生物，

that you've probably never heard of:

你们可能从没有听说过：

its name is Prochlorococcus,

它叫原绿球藻，

and it's really an amazing little being.

是一种非常神奇的微生物。

For one thing, its ancestors

一方面，它的祖先

changed the earth in ways that made it possible for us to evolve,

改变了地球环境， 使其适合人类的演化，

and hidden in its genetic code

而隐藏在其遗传密码中的

is a blueprint

是一个蓝图，

that may inspire ways to reduce our dependency on fossil fuel.

可以启发我们找到减少 对化石燃料依赖的方法。

But the most amazing thing

但最让人惊奇的是

is that there are three billion billion billion

地球上拥有3乘10的27次方之多的

of these tiny cells on the planet,

这种微生物，

and we didn't know they existed until 35 years ago.

而我们直至35年前 才知道它们的存在。

So to tell you their story,

要给你们讲它们的故事，

I need to first take you way back,

我需要首先带你们回到过去，

four billion years ago, when the earth might have looked something like this.

40亿年前的地球可能长这样。

There was no life on the planet,

毫无生息，

there was no oxygen in the atmosphere.

大气层中没有一点氧气。

So what happened to change that planet into the one we enjoy today,

是什么让地球变得 像今天这样宜居，

teeming with life,

充满生命，

teeming with plants and animals?

到处是植物和动物？

Well, in a word, photosynthesis.

一个词，光合作用。

About two and a half billion years ago,

在大约25亿年前，

some of these ancient ancestors of Prochlorococcus evolved

原绿球藻的部分 远古祖先发生了进化，

so that they could use solar energy

这样它们就可以使用太阳能，

and absorb it

吸收这些能量，

and split water into its component parts of oxygen and hydrogen.

并利用其将水分解成氧和氢。

And they used the chemical energy produced

它们使用产生的化学能

to draw CO2, carbon dioxide, out of the atmosphere

把二氧化碳从大气中抽取出来，

and use it to build sugars and proteins and amino acids,

并用于制造糖分，蛋白质和氨基酸，

all the things that life is made of.

所有这些组成生命的元素。

And as they evolved and grew more and more

随着它们不断演化，数量日渐增加，

over millions and millions of years,

历经数百万年之后，

that oxygen accumulated in the atmosphere.

大气中的氧气慢慢积累起来。

Until about 500 million years ago,

直到大约5亿前，

there was enough in the atmosphere that larger organisms could evolve.

大气中的氧气足够多到 让更大的生物可以进化。

There was an explosion of life-forms,

迎来了生命形态的大爆发，

and, ultimately, we appeared on the scene.

最终，人类出现在了历史舞台上。

While that was going on,

在这一切发生的过程中，

some of those ancient photosynthesizers died

部分这些远古的光合作用系统死去，

and were compressed and buried,

被压缩和埋葬，

and became fossil fuel

变成了用碳键

with sunlight buried in their carbon bonds.

储存太阳能量的化石燃料。

They're basically buried sunlight in the form of coal and oil.

它们基本上是用煤炭 和石油的形式储存太阳能的。

Today's photosynthesizers,

今天的光合作用系统，

their engines are descended from those ancient microbes,

它们的引擎是那些 古老微生物的后代，

and they feed basically all of life on earth.

它们基本上养育了 地球上所有的生物。

Your heart is beating using the solar energy

你心脏的跳动使用的是来自植物

that some plant processed for you,

为你加工的太阳能，

and the stuff your body is made out of

你的身体部件是由植物为你加工的

is made out of CO2

二氧化碳

that some plant processed for you.

制造而成。

Basically, we're all made out of sunlight and carbon dioxide.

总的来说，我们都由 阳光和二氧化碳所造。

Fundamentally, we're just hot air.

说白了，我们只是热空气罢了。

(Laughter)

（笑声）

So as terrestrial beings,

作为陆地生物，

we're very familiar with the plants on land:

我们对地上的植物很熟悉：

the trees, the grasses, the pastures, the crops.

树木，草，牧场，庄稼。

But the oceans are filled with billions of tons of animals.

但海洋里充满了数十亿吨的动物。

Do you ever wonder what's feeding them?

你们有没有好奇它们都吃些什么？

Well there's an invisible pasture

海洋里面有一片看不见的牧场，

of microscopic photosynthesizers called phytoplankton

由一种叫做浮游植物的 微型光合成器组成，

that fill the upper 200 meters of the ocean,

填满了海洋顶层的200米，

and they feed the entire open ocean ecosystem.

它们为整个海洋生态系统提供食物。

Some of the animals live among them and eat them,

有些动物生活于其中，以它们为食，

and others swim up to feed on them at night,

另一些晚上游过来吞食它们，

while others sit in the deep and wait for them to die and settle down

还有一些静坐海洋深处， 等待它们死亡，沉降，

and then they chow down on them.

从而享受美餐。

So these tiny phytoplankton,

这些微小的浮游植物

collectively, weigh less than one percent of all the plants on land,

加在一起，只占地球 植物重量不到1/100，

but annually they photosynthesize as much as all of the plants on land,

但每年它们的光合作用总量 不亚于陆地上的所有植物，

including the Amazon rainforest

包括亚马逊雨林在内，

that we consider the lungs of the planet.

这个我们视为地球之肺的雨林。

Every year, they fix 50 billion tons of carbon

每一年，它们以二氧化碳的形式

in the form of carbon dioxide into their bodies

在体内固定500亿吨的碳，

that feeds the ocean ecosystem.

从而为整个海洋系统提供食物。

How does this tiny amount of biomass

这些微小的生物是如何产生

produce as much as all the plants on land?

跟地上的植物一样多的氧气的呢？

Well, they don't have trunks and stems

它们并没有树干和茎，

and flowers and fruits and all that to maintain.

鲜花和果实这些维持生命的东西。

All they have to do is grow and divide and grow and divide.

它们所要做的无非是 重复地成长和分裂。

They're really lean little photosynthesis machines.

它们是非常小的光合作用机器。

They really crank.

真是全力以赴地在工作。

So there are thousands of different species of phytoplankton,

有成千上万种不同种类的浮游植物，

come in all different shapes and sizes,

有不同的形状和大小，

all roughly less than the width of a human hair.

它们的尺寸都小于 人类的头发宽度。

Here, I'm showing you some of the more beautiful ones,

这里，我给大家展示 其中最漂亮的一些，

the textbook versions.

几乎是教科书版本。

I call them the charismatic species of phytoplankton.

我称它们为魅力非凡的浮游植物。

And here is Prochlorococcus.

这就是原绿球藻。

I know,

我知道。

it just looks like a bunch of schmutz on a microscope slide.

这看起来就像是 显微玻璃片上的脏东西。

(Laughter)

（笑声）

But they're in there,

但它们就在其中，

and I'm going to reveal them to you in a minute.

我马上就会展示给你们看。

But first I want to tell you how they were discovered.

但首先，我想告诉大家 它们是如何被发现的。

About 38 years ago,

在大约38年前，

we were playing around with a technology in my lab called flow cytometry

我们在实验室里时兴玩一项 叫做流式细胞术的技术，

that was developed for biomedical research for studying cells like cancer cells,

该技术是为研究癌细胞等 生物医学研究而开发的，

but it turns out we were using it for this off-label purpose

但结果，我们用它来 实现这个标示外的目的，

which was to study phytoplankton, and it was beautifully suited to do that.

用于研究浮游植物， 也是非常适合的。

And here's how it works:

这是它工作的原理：

so you inject a sample in this tiny little capillary tube,

你把样本注入到这个 微小的毛细管中，

and the cells go single file by a laser,

细胞在激光照射下一个个通过，

and as they do, they scatter light according to their size

在这过程中，它们根据 不同的大小散射光线，

and they emit light according to whatever pigments they might have,

并根据它们可能含有的色素发出光，

whether they're natural or whether you stain them.

不管是天然的还是后天被染色的。

And the chlorophyl of phytoplankton,

浮游植物的叶绿素

which is green,

是绿色的，

emits red light when you shine blue light on it.

当你把蓝光照射在 上面时，就发出红光。

And so we used this instrument for several years

所以我们使用这种仪器好些年

to study our phytoplankton cultures,

去研究我们的浮游植物培养群，

species like those charismatic ones that I showed you,

这种我给你们看的有魅力的物种，

just studying their basic cell biology.

只是研究它们基本的细胞生物学。

But all that time, we thought, well wouldn't it be really cool

但在这段时间里， 我们想，假如我们把

if we could take an instrument like this out on a ship

这种仪器带到船上，

and just squirt seawater through it

用它来喷洒海水，

and see what all those diversity of phytoplankton would look like.

看看多样性的浮游植物 会是什么样子，这不是很酷吗？

So I managed to get my hands

所以我设法得到了

on what we call a big rig in flow cytometry,

我们称之为流式细胞仪中的大钻机，

a large, powerful laser

一个大型，强大的激光器，

with a money-back guarantee from the company

并得到了卖方假如无法在船上工作，

that if it didn't work on a ship, they would take it back.

可以退货退款的保证。

And so a young scientist that I was working with at the time,

于是一个我一直在合作的年轻科学家，

Rob Olson, was able to take this thing apart,

罗伯 · 奥尔森，把这东西拆开，

put it on a ship, put it back together and take it off to sea.

运到船上，再重新 组装好，带到海里去。

And it worked like a charm.

它的效果出人意料的好。

We didn't think it would, because we thought the ship's vibrations

我们没想到效果这么好， 因为我们以为船的晃动

会阻碍激光的聚焦，

would get in the way of the focusing of the laser,

但它的效果真的十分惊艳。

but it really worked like a charm.

于是，我们绘制了整个海洋的 浮游植物分布图。

And so we mapped the phytoplankton distributions across the ocean.

For the first time, you could look at them one cell at a time in real time

这是首次可以实时地 看一个细胞单元，

and see what was going on -- that was very exciting.

看看发生了什么—— 这实在非常令人兴奋。

But one day, Rob noticed some faint signals

有一天，罗伯注意到机器中

coming out of the instrument

有一些微弱的信号，

that we dismissed as electronic noise

这些信号一年来一直被我们当做

for probably a year

电子噪音，

before we realized that it wasn't really behaving like noise.

直至我们意识到， 它们并不是噪音。

It had some regular patterns to it.

它的信号表现出了一些固定的模式。

To make a long story short,

长话短说，

it was tiny, tiny little cells,

它是非常非常微小的细胞，

less than one-one hundredth the width of a human hair

不到人类头发宽度的百分之一，

that contain chlorophyl.

它含有叶绿素。

That was Prochlorococcus.

这就是原绿球藻。

So remember this slide that I showed you?

还记得刚才展示过的 这张幻灯片吗？

If you shine blue light on that same sample,

如果你用蓝光照射这些样本，

this is what you see:

就会看到这样一幕：

two tiny little red light-emitting cells.

两个微小的红色发光细胞。

Those are Prochlorococcus.

这些都是原绿球藻。

They are the smallest and most abundant photosynthetic cell on the planet.

它们是地球上最小， 但数量最多的光合细胞。

At first, we didn't know what they were,

一开始，我们不知道它们是什么，

so we called the "little greens."

所以叫它们“小绿”，

It was a very affectionate name for them.

这是一个非常亲切的称呼。

Ultimately, we knew enough about them to give them the name Prochlorococcus,

最后，我们对它们有了深入的了解， 就把它取名叫原绿球藻，

which means "primitive green berry."

意思是“原始的绿色浆果”。

And it was about that time

大概是在那个时候

that I became so smitten by these little cells

我就被这些小细胞迷住了，

that I redirected my entire lab to study them and nothing else,

我把我整个实验室的 研究方向都转到了它们身上，

and my loyalty to them has really paid off.

而我对它们的忠诚 也得到了丰厚的回报。

They've given me a tremendous amount, including bringing me here.

它们带给了我很多， 也让我今天能够站在这里。

(Applause)

（鼓掌）

So over the years, we and others, many others,

过去那些年，我和很多其他人，

have studied Prochlorococcus across the oceans

穿越了各个海域研究原绿球藻，

and found that they're very abundant over wide, wide ranges

发现它们在开放的海洋生态中的

in the open ocean ecosystem.

数量十分庞大，且分布广阔。

They're particularly abundant in what are called the open ocean gyres.

它们在公海环流中尤其丰富。

These are sometimes referred to as the deserts of the oceans,

这些区域有时被称为海洋的沙漠，

but they're not deserts at all.

但它们其实根本不是沙漠。

Their deep blue water is teeming

深蓝色的海水

with a hundred million Prochlorococcus cells per liter.

每升富含1亿个原绿球藻。

If you crowd them together like we do in our cultures,

如果把它们按 处理培养群那样聚在一起，

you can see their beautiful green chlorophyl.

就可以看到它们美丽的绿色叶绿素。

One of those test tubes has a billion Prochlorococcus in it,

其中一个试管中有 10亿个原绿球菌，

and as I told you earlier,

正如我刚才提到的，

there are three billion billion billion of them on the planet.

地球上有3乘10的27次方的原绿球藻，

That's three octillion,

相当于3倍的10亿的3次方，

if you care to convert.

如果你想转换的话。

(Laughter)

（笑声）

And collectively, they weigh more than the human population

它们的重量加起来 超过了人类总人口的重量，

and they photosynthesize as much as all of the crops on land.

光合作用程度 跟地球上所有作物一样多。

They're incredibly important in the global ocean.

对全球海洋来说非常重要。

So over the years, as we were studying them

这些年来，随着研究的不断推进，

and found how abundant they were,

我们发现它们的含量如此丰富，

we thought, hmm, this is really strange.

不禁感到很奇怪。

How can a single species be so abundant across so many different habitats?

一个物种如何能在如此多的 不同栖息地都如此丰富？

And as we isolated more into culture,

当我们把更多的原绿球藻 隔离在培养液中，

we learned that they are different ecotypes.

我们了解到它们是 不同的生态类型。

There are some that are adapted to the high-light intensities

有一些适应高光强度的

in the surface water,

表层水，

and there are some that are adapted to the low light in the deep ocean.

另一些则适应深海的低光环境。

In fact, those cells that live in the bottom of the sunlit zone

事实上，那些生活在 阳光照射区底部的细胞

are the most efficient photosynthesizers of any known cell.

是所有已知细胞中 最有效的光合成器。

And then we learned that there are some strains

然后我们了解到有一些菌株

that grow optimally along the equator,

在赤道上生长得最好，

where there are higher temperatures,

那里温度更高，

and some that do better at the cooler temperatures

有一些则在更低温度中表现更好，

as you go north and south.

沿着经线考察就会发现。

So as we studied these more and more and kept finding more and more diversity,

所以当我们更深入地研究这些问题时， 就会不断发现更多的多样性，

we thought, oh my God, how diverse are these things?

我们不禁感叹，老天， 这些东西到底有多少种？

And about that time, it became possible to sequence their genomes

大约在那个时候，技术已经发展到 可以对它们的基因组进行测序了，

and really look under the hood and look at their genetic makeup.

可以仔细看看它们的基因组成。

And we've been able to sequence the genomes of cultures that we have,

我们已经能够对所拥有的 培养物的基因组进行测序，

but also recently, using flow cytometry,

但也在最近，使用流式细胞术，

we can isolate individual cells from the wild

我们可以将单个细胞 从野生环境中分离出来，

and sequence their individual genomes,

并对它们的个体基因组进行测序，

and now we've sequenced hundreds of Prochlorococcus.

现在我们已经对数百种 原球菌进行了测序。

And although each cell has roughly 2,000 genes --

尽管每个细胞大约只有 2000个基因——

that's one tenth the size of the human genome --

是人类基因组的1/10——

as you sequence more and more,

但随着测序越来越多，

you find that they only have a thousand of those in common

你会发现它们之间 有上千种基因是相似的，

and the other thousand for each individual strain

而每个个体的另外一千个基因

is drawn from an enormous gene pool,

都是从一个巨大的 基因库中提取出来的，

and it reflects the particular environment that the cell might have thrived in,

它反映了细胞可能 在其中生长的特殊环境，

not just high or low light or high or low temperature,

不只是在光照强度和温度上有差别，

but whether there are nutrients that limit them

还包括是否有营养物质限制了它们，

like nitrogen, phosphorus or iron.

比如氮、磷或铁。

It reflects the habitat that they come from.

同时也反映了它们的栖息地。

Think of it this way.

可以这样想。

If each cell is a smartphone

如果每个细胞是部智能手机，

and the apps are the genes,

应用是基因，

when you get your smartphone, it comes with these built-in apps.

当你拿到智能手机时， 它已经预装了一些应用。

Those are the ones that you can't delete if you're an iPhone person.

这些预装应用你是无法删除的， 如果你用的是iPhone。

You press on them and they don't jiggle and they don't have x's.

你按下它们，它们不会抖动， 不会出现删除标记。

即便你不喜欢它们， 也别想清除掉它们。

Even if you don't want them, you can't get rid of them.

（笑声）

(Laughter)

Those are like the core genes of Prochlorococcus.

这些是原绿球藻的核心基因。

They're the essence of the phone.

它们就像手机的核心。

But you have a huge pool of apps to draw upon

但你也有一个巨大的应用库，

to make your phone custom-designed for your particular lifestyle and habitat.

可以根据你的生活方式和习惯 来对你的手机进行个性化设置。

If you travel a lot, you'll have a lot of travel apps,

如果你到处旅行， 就会有很多旅行应用，

if you're into financial things, you might have a lot of financial apps,

如果你是搞金融的， 可能就有很多财经应用，

or if you're like me,

或者如果你像我一样，

you probably have a lot of weather apps,

你可能会有一大堆天气应用，

希望里面起码有一个 预测能让你心花怒放。

hoping one of them will tell you what you want to hear.

(Laughter)

（笑声）

And I've learned the last couple days in Vancouver

我在温哥华最后几天学到的是

that you don't need a weather app -- you just need an umbrella.

你未必需要天气应用， 你只需要一把伞。

So --

所以——

(Laughter)

（笑声）

(Applause)

（鼓掌）

So just as your smartphone tells us something about how you live your life,

所以正如你的智能手机 能够告诉我们一些你的生活，

your lifestyle,

你的生活方式那样，

reading the genome of a Prochlorococcus cell

阅读原绿球藻细胞的基因

tells us what the pressures are in its environment.

能够告诉我们原绿球藻 所生活的环境，比如压力强度。

It's like reading its diary,

就如同阅读它的日记，

not only telling us how it got through its day or its week,

不仅告诉我们它的一天， 或一周如何度过，

but even its evolutionary history.

甚至还包括它们的演化历史。

As we studied -- I said we've sequenced hundreds of these cells,

随着进一步的研究， 我们已经测序了几百种这些细胞，

and we can now project

我们现在已经可以预估

what is the total genetic size --

整个基因集合的大小——

gene pool --

基因库——

of the Prochlorococcus federation, as we call it.

原绿球藻的基因联邦， 我们是这样称呼它的。

It's like a superorganism.

这就像一个超级有机体。

And it turns out that projections are

预测的结果是

that the collective has 80,000 genes.

整个集合共有8万个基因。

That's four times the size of the human genome.

相当于人类基因组的4倍。

And it's that diversity of gene pools

正是这多样化的基因库

that makes it possible for them

让它们可以

to dominate these large regions of the oceans

统治这广阔的海域，

and maintain their stability

一年接一年地维持

year in and year out.

它们的稳定性。

So when I daydream about Prochlorococcus,

当我畅想着原绿球藻的的时候，

which I probably do more than is healthy --

我做这个可不仅是为了健康——

(Laughter)

（笑声）

I imagine them floating out there,

我想象它们漂来漂去，

doing their job,

做着本职工作，

maintaining the planet,

维持地球的运转，

feeding the animals.

喂饱动物，

But also I inevitably end up

但同时也不可避免想到

thinking about what a masterpiece they are,

它们真是大自然的鬼斧神工，

finely tuned by millions of years of evolution.

历经了数百万年精细的进化。

With 2,000 genes,

只有2000个基因，

they can do what all of our human ingenuity

它们就做到了我们人类

has not figured out how to do yet.

还没有搞明白怎么做的事情。

They can take solar energy, CO2

它们可以把太阳能，CO2

and turn it into chemical energy in the form of organic carbon,

以有机碳的方式变成化学能，

locking that sunlight in those carbon bonds.

把阳光锁在那些碳键中。

If we could figure out exactly how they do this,

如果我们能够弄明白 它们是如何做到的，

it could inspire designs

就可以激发我们设计一些方法来

that could reduce our dependency on fossil fuels,

减少对化学燃料的依赖，

which brings my story full circle.

这也就让我的故事圆满了。

The fossil fuels that are buried that we're burning

我们用来燃烧的 埋葬在地下的化石燃料

took millions of years for the earth to bury those,

需要地球花费长达 数百万年的时间去积累，

including those ancestors of Prochlorococcus,

包括这些原绿球藻的远古祖先，

and we're burning that now in the blink of an eye

而我们眨眼之间就把它们燃烧了，

on geological timescales.

从地质时间的尺度来看就是一瞬间。

Carbon dioxide is increasing in the atmosphere.

二氧化碳在大气中积累。

It's a greenhouse gas.

这是一种温室气体。

The oceans are starting to warm.

海洋开始变得温暖。

So the question is, what is that going to do

所以问题是，我的原绿球藻

for my Prochlorococcus?

接下来会怎样？

And I'm sure you're expecting me to say that my beloved microbes are doomed,

我确定你们会觉得我想说， 我心爱的微生物要遭受灭顶之灾了，

but in fact they're not.

但事实并非如此。

Projections are that their populations will expand as the ocean warms

我们的预测是，随着海水 温度上升，它们的数量会在

to 30 percent larger by the year 2100.

2100年增加30%。

Does that make me happy?

这让我们开心了吗？

Well, it makes me happy for Prochlorococcus of course --

当然，这让我为原绿球藻感到高兴——

(Laughter)

（笑声）

but not for the planet.

但对地球可就不是这么回事儿了。

There are winners and losers

在这场我们正在进行的

in this global experiment that we've undertaken,

全球实验中，难免会有输家和赢家。

and it's projected that among the losers

而根据预计，输家是那些

will be some of those larger phytoplankton,

更大一些的浮游植物，

those charismatic ones

那些有魅力的

which are expected to be reduced in numbers,

预期数量会大为减少，

and they're the ones that feed the zooplankton that feed the fish

它们是为人类喜欢捕捞的鱼类

that we like to harvest.

提供食物的浮游植物。

So Prochlorococcus has been my muse for the past 35 years,

在过去35年中， 原绿球藻就是我的命运女神，

but there are legions of other microbes out there

但还有很多其他的微生物

maintaining our planet for us.

在帮我们维持地球的环境平衡。

They're out there

它们就在那儿，

ready and waiting for us to find them so they can tell their stories, too.

准备就绪，等待着我们去寻找它们， 并传颂它们的故事。

Thank you.

谢谢。

(Applause)

（鼓掌）