The tiny creature that secretly powers the planet | Penny Chisholm

譯者: Lilian Chiu 審譯者: Yanyan Hong

I'd like to introduce you to a tiny microorganism

我要向各位介紹 一種極小的微生物，

that you've probably never heard of:

各位可能從來沒有聽過：

its name is Prochlorococcus,

它叫做原綠球藻，

and it's really an amazing little being.

它是種非常不可思議的小生命。

For one thing, its ancestors

一則，它的祖先

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

改變了地球， 讓我們在地球上的演化成為可能，

and hidden in its genetic code

而隱藏在它的基因碼之中的，

is a blueprint

是一張藍圖，

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

或許可以啟發一些讓我們 減少對化石燃料依賴的方式。

But the most amazing thing

但最不可思議的是，

is that there are three billion billion billion

在地球上有三千億億億個

of these tiny cells on the planet,

這種微小細胞，

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

且一直到三十五年前 我們才知道它們的存在。

So to tell you their story,

要說它們的故事之前，

I need to first take you way back,

我得要先帶各位回頭，

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

回到四十億年前，

當時地球可能看起來還像是這樣子。

There was no life on the planet,

地球上沒有生命，

there was no oxygen in the atmosphere.

大氣中沒有氧氣。

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

發生了什麼事，讓地球改變成 我們現今能享受的模樣，

teeming with life,

充滿生命，

teeming with plants and animals?

充滿植物和動物？

Well, in a word, photosynthesis.

用個詞來說，就是「光合作用」。

About two and a half billion years ago,

大約二十五億年前，

some of these ancient ancestors of Prochlorococcus evolved

原綠球藻的某些古老祖先演化了，

so that they could use solar energy

它們開始能使用太陽能，

and absorb it

吸收它，

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

並將水分解成氧和氫。

And they used the chemical energy produced

它們用這過程所產生的化學能

to draw CO2, carbon dioxide, out of the atmosphere

來把二氧化碳從大氣中汲取出來，

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

用它做成糖、蛋白質，和氨基酸，

all the things that life is made of.

這些都是生命的組成成份。

And as they evolved and grew more and more

隨著它們演化及不斷地成長，

over millions and millions of years,

經過了數百萬年，

that oxygen accumulated in the atmosphere.

大氣中累積了氧氣。

Until about 500 million years ago,

直到大約五億年前，

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

大氣中有足夠的氧氣， 讓比較大的有機體能夠演化。

There was an explosion of life-forms,

各種生命形式劇增，

and, ultimately, we appeared on the scene.

最終，我們人類也出現了。

While that was going on,

在那個過程中，

some of those ancient photosynthesizers died

有些古老的光合作用生物死亡了，

and were compressed and buried,

它們被壓縮及掩埋，

and became fossil fuel

變成了化石燃料，

with sunlight buried in their carbon bonds.

在它們的碳鍵當中埋藏了太陽光。

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

基本上，可以說它們就是太陽光， 以煤和石油的形式被掩埋。

Today's photosynthesizers,

現今行光合作用的生物，

their engines are descended from those ancient microbes,

它們的引擎就是由那些 古老的微生物所傳下來的，

and they feed basically all of life on earth.

基本上，它們養活了 地球上所有的生命。

Your heart is beating using the solar energy

你的心臟跳動，用的是由某些植物

that some plant processed for you,

為你處理過的太陽能，

and the stuff your body is made out of

你的身體組成成份

is made out of CO2

是由某些植物

that some plant processed for you.

為你處理過的二氧化碳。

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

基本上，我們都是由 太陽光和二氧化碳所組成。

Fundamentally, we're just hot air.

從根本上來看，我們只是熱空氣。

(Laughter)

（笑聲）

So as terrestrial beings,

身為陸地生物，

we're very familiar with the plants on land:

我們對地面上的植物非常熟悉：

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

樹木、草、牧草、作物。

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

但海洋中還有數十億種 各式各樣的動物。

Do you ever wonder what's feeding them?

你可曾納悶牠們靠什麼維生？

Well there's an invisible pasture

有一種看不見的牧草，

of microscopic photosynthesizers called phytoplankton

只能從顯微鏡看到的 光合作用生物，叫做浮游植物，

that fill the upper 200 meters of the ocean,

它們滿佈在海洋上層 兩百公尺的區域，

and they feed the entire open ocean ecosystem.

整個開放的海洋生態系統的 食物都要靠它們。

Some of the animals live among them and eat them,

有些動物住在它們當中， 以它們為食，

and others swim up to feed on them at night,

其他的動物晚上游上來吃它們，

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

還有深海中的動物， 等它們死亡後沉澱下來，

and then they chow down on them.

再來吃它們。

So these tiny phytoplankton,

所以，這些微小的浮游植物，

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

全部加在一起還不到 地面所有植物重量的 1%，

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

但每年，它們行光合作用的產能 並不輸給地面上的植物，

including the Amazon rainforest

包括被我們視為是地球肺部的

that we consider the lungs of the planet.

亞馬遜雨林在內。

Every year, they fix 50 billion tons of carbon

每年，它們將五百億噸的碳，

以二氧化碳的形式 存放在它們的體內，

in the form of carbon dioxide into their bodies

that feeds the ocean ecosystem.

成為海洋生態系統的食物。

How does this tiny amount of biomass

這麼微量的生物量，產量是如何

produce as much as all the plants on land?

能不輸給陸地上的所有植物？

Well, they don't have trunks and stems

嗯，它們沒有樹幹和莖，

and flowers and fruits and all that to maintain.

也沒有花和果實，不用去維持這些。

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

它們只需要專心 成長和分裂，成長和分裂。

They're really lean little photosynthesis machines.

它們其實算是很精實的 小型光合作用機器。

They really crank.

它們的動作真的很快。

So there are thousands of different species of phytoplankton,

所以，浮游植物的種類有數千種，

come in all different shapes and sizes,

形狀、大小皆不同，

all roughly less than the width of a human hair.

幾乎都不到一根人類頭髮的寬度。

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

我給各位看的， 是其中一些比較漂亮的，

the textbook versions.

教科書版本的。

I call them the charismatic species of phytoplankton.

我稱它們為有魅力的浮游植物物種。

And here is Prochlorococcus.

這是原綠球藻。

I know,

我知道，

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

在顯微鏡載片上， 它看起來就像一堆污垢。

(Laughter)

（笑聲）

But they're in there,

但它們就在那裡，

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

我很快就會向各位揭露它們。

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

但首先，我想要告訴各位， 它們是如何被發現的。

About 38 years ago,

大約三十八年前，

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

我們在我的實驗室中， 試玩一種技術叫做流式細胞術，

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

它是為了生物醫學研究而發展的， 用來研究像癌症細胞這類的細胞，

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

但結果，我們把它拿來 做說明標籤上沒寫的用途，

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

也就是研究浮游植物， 且還非常適合這個用途。

And here's how it works:

做法如下：

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

我們將樣本注射到 極小的毛細管當中，

and the cells go single file by a laser,

細胞會成一路縱隊，通過雷射，

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

通過的時候，它們就會因為 大小不同而造成不同的散射光，

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

它們也會根據它們 具有的顏色來發光，

whether they're natural or whether you stain them.

不論是它們天生的 或是你人工染上的顏色。

And the chlorophyl of phytoplankton,

而浮游植物的葉綠素

which is green,

是綠色的，

emits red light when you shine blue light on it.

當你對它照射藍光時， 它會發出紅光。

And so we used this instrument for several years

所以，多年來我們用這項工具

to study our phytoplankton cultures,

來研究我們的浮游植物培養，

species like those charismatic ones that I showed you,

比如我剛剛給各位看的 那些迷人物種，

just studying their basic cell biology.

只是研究它們的基本細胞生物學。

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

但那段時間，我們總在想 一個應該會很酷的點子，

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

把類似這樣的工具放到一艘船上，

and just squirt seawater through it

注入海水，通過這工具，

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

來看看浮游植物的多樣性， 看起來會是什麼樣子的。

So I managed to get my hands

所以我想辦法弄到了

on what we call a big rig in flow cytometry,

我們在流式細胞術中 所謂的「鑽探設備」，

a large, powerful laser

一種大型、強力的雷射，

with a money-back guarantee from the company

還有公司的退款保證，

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

若在船上無法使用， 他們願意接受退貨。

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

所以，當時和我合作的 一位年輕科學家

Rob Olson, was able to take this thing apart,

叫做羅勃歐森， 他能把這東西拆開，

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

帶到一艘船上， 再組裝起來，帶它出海。

And it worked like a charm.

結果是順利得獲得大成功。

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

我們沒預期會成功， 因為我們以為船的震動

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

會影響到雷射的聚焦，

but it really worked like a charm.

但真的就是個大成功。

And so we mapped the phytoplankton distributions across the ocean.

所以我們在圖上畫出了 海中浮游植物的分佈。

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

這是頭一次，

能夠一次觀看一個細胞， 且影像是即時的，

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

能看出發生了什麼事—— 那是很讓人興奮的。

But one day, Rob noticed some faint signals

但有一天，羅勃注意到 這個工具出現了

coming out of the instrument

一些微弱的訊號，

that we dismissed as electronic noise

我們當作是電子噪音 所以沒有理會，

for probably a year

有一年的時間都如此，

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

後來我們才發現， 它的行為並不像是噪音。

It had some regular patterns to it.

它有一些規則的模式。

To make a long story short,

長話短說，

it was tiny, tiny little cells,

它是很微小很微小的細胞，

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

還不到人類頭髮寬度的百分之一，

that contain chlorophyl.

且它含有葉綠素。

That was Prochlorococcus.

那就是原綠球藻。

So remember this slide that I showed you?

還記得我剛剛給各位看的載片嗎？

If you shine blue light on that same sample,

如果你對同樣的樣本照射藍光，

this is what you see:

你就會看到：

two tiny little red light-emitting cells.

兩個發射紅光的小細胞。

Those are Prochlorococcus.

那些就是原綠球藻。

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

它們是地球上最小 且最大量的光合作用細胞。

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

一開始，我們不知道它們是什麼，

so we called the "little greens."

所以我們叫它們「小綠」。

It was a very affectionate name for them.

那是個非常親切的名字。

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

最終，我們對它們夠了解了， 取了 Prochlorococcus 這個名字，

which means "primitive green berry."

意思就是「原綠球藻」。

And it was about that time

大約在那個時候，

that I became so smitten by these little cells

我完全愛上了這些小細胞，

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

我改變整個實驗室的方向， 不做別的就專門研究它們，

and my loyalty to them has really paid off.

我對它們的忠誠真的讓我得到報償。

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

它們給了我好多好多， 包括讓我來到這裡。

(Applause)

（掌聲）

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

這些年來，我和其他人， 許多其他人，

have studied Prochlorococcus across the oceans

在研究海洋中的原綠球藻，

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

發現在開放的海洋生態系統中，

in the open ocean ecosystem.

它們的種類和數量都非常多。

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

在開放海洋的渦流中 特別多原綠球藻。

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

這些渦流有時候 被稱為海洋的沙漠，

but they're not deserts at all.

但它們完全不是沙漠。

Their deep blue water is teeming

它們的深藍海水中滿是原綠球藻，

with a hundred million Prochlorococcus cells per liter.

每公升就有一億個原綠球藻。

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

若像我們這樣把培養的 原綠球藻聚集在一起，

you can see their beautiful green chlorophyl.

就可以看見它們 漂亮的綠色葉綠素。

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

只要一根這種試管， 裡面就有十億個原綠球藻，

and as I told you earlier,

我剛才有提過，

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

地球上有三千億億億個原綠球藻。

That's three octillion,

如果你想換算的話，

if you care to convert.

那是三乘以千的九次方。 （註：3 x 10 的 27 次方）

(Laughter)

（笑聲）

And collectively, they weigh more than the human population

它們的總重量比全人類加起來還重，

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

它們行的光合作用， 和陸地上的作物一樣多。

They're incredibly important in the global ocean.

在全球海洋中，它們非常重要。

So over the years, as we were studying them

這些年來，我們研究它們，

and found how abundant they were,

發現它們的數量多驚人，

we thought, hmm, this is really strange.

我們心想，嗯，這好奇怪。

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

怎麼可能有單一物種在這麼多 不同的棲息地都有很大的數量？

And as we isolated more into culture,

我們隔離培養更多的原綠球藻，

we learned that they are different ecotypes.

發現它們的生態型並不相同。

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

有些能適應在接近水表面的

in the surface water,

高光強度，

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

有些則能適應深海中的低光度。

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

事實上，住在太陽光區域 底部的那些細胞

are the most efficient photosynthesizers of any known cell.

是所有已知細胞中， 光合作用效率最高的。

And then we learned that there are some strains

我們接著發現，有些種類

that grow optimally along the equator,

最適合沿著赤道生長，

where there are higher temperatures,

那裡的溫度比較高，

and some that do better at the cooler temperatures

向北和向南，則還有一些 更能生長在較冷溫度的種類。

as you go north and south.

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

隨著我們對它們的研究越來越多， 且不斷發現更多樣的種類，

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

我們心想，天啊， 這些東西到底有多少變化？

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

大約在那時，已經有可能 定序它們的基因組，

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

真正去深入了解它們的基因組成。

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

我們也能夠將我們的 培養物做基因定序，

but also recently, using flow cytometry,

此外，近期，用流式細胞術，

we can isolate individual cells from the wild

我們可以分離來自野外的個別細胞，

and sequence their individual genomes,

並針對它們個別的基因組做定序，

and now we've sequenced hundreds of Prochlorococcus.

現在我們已經將數百個 原綠球藻做了定序。

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

雖然每個細胞都有 大約兩千個基因——

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

那是人類基因組 大小的十分之一——

as you sequence more and more,

隨著越來越多定序完成，

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

會發現它們只有一千個共同基因，

and the other thousand for each individual strain

每一種種類的另外一千個

is drawn from an enormous gene pool,

都是從一個巨大的 基因庫中取出來的，

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

反應出該細胞能夠 繁盛生長的特定環境，

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

不只是光強度的高低或溫度的高低，

but whether there are nutrients that limit them

還包括是否有營養物限制它們，

like nitrogen, phosphorus or iron.

比如氮、磷，或鐵。

It reflects the habitat that they come from.

這會反應出它們的來源棲息地。

Think of it this way.

用這種方式來看。

If each cell is a smartphone

如果每個細胞是一支智慧手機，

and the apps are the genes,

應用程式是基因，

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

當你拿到你的智慧手機時， 本身就有一些內建的應用程式。

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

若你用的是 iPhone， 那些應用程式是你無法刪除的。

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

長按它們的圖示，它們不會抖動， 也沒有「X」出現。

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

即使你不想要那些 應用程式，也擺脫不了。

(Laughter)

（笑聲）

Those are like the core genes of Prochlorococcus.

那些就像是原綠球藻的核心基因。

They're the essence of the phone.

它們是手機的本質。

But you have a huge pool of apps to draw upon

但你有一個很大的 應用程式庫讓你可以取用，

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

讓你的手機客製化設計， 配合你自己的生活方式和習慣。

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

如果你常旅行， 你就會有很多旅行應用程式，

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

如果你的興趣在財務， 就會有很多財務應用程式，

or if you're like me,

或者，如果你和我很像，

you probably have a lot of weather apps,

你可能會有很多天氣應用程式，

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

希望其中有一個會告訴你 你想要聽的結果。

(Laughter)

（笑聲）

And I've learned the last couple days in Vancouver

過去這幾天在溫哥華 我學到了一件事，

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

你不需要天氣應用程式—— 你只需要一把傘。

So --

所以——

(Laughter)

（笑聲）

(Applause)

（掌聲）

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

所以，看了你的智慧手機就能知道 一些關於你如何過生活的資訊，

your lifestyle,

了解你的生活方式，

reading the genome of a Prochlorococcus cell

同樣地，去讀原綠球藻細胞的基因組

tells us what the pressures are in its environment.

也能讓我們知道它所處環境的壓力。

It's like reading its diary,

就像是在讀它的日記，

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

不只能了解它如何 度過這一天或這一週，

but even its evolutionary history.

甚至還能知道它的演化史。

根據我們的研究——前面提過 我們已定序了數百個這類細胞，

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

and we can now project

我們現在可以預測

what is the total genetic size --

整個基因的大小——

gene pool --

基因庫的大小——

of the Prochlorococcus federation, as we call it.

我們所謂原綠球藻聯邦的基因庫。

It's like a superorganism.

它就像是超個體。

And it turns out that projections are

預測的結果是，

that the collective has 80,000 genes.

總共有八萬個基因。

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

那是人類基因組大小的四倍。

And it's that diversity of gene pools

因為基因庫的多樣性，

that makes it possible for them

讓原綠球藻可以

to dominate these large regions of the oceans

支配海洋這些廣大的區域，

and maintain their stability

且能維持穩定，

year in and year out.

年復一年。

So when I daydream about Prochlorococcus,

當我在作關於原綠球藻的白日夢時，

which I probably do more than is healthy --

我作這種白日夢的頻率 可能已經到不太健康——

(Laughter)

（笑聲）

I imagine them floating out there,

我想像它們漂浮在那裡，

doing their job,

盡它們的本份，

maintaining the planet,

維護地球，

feeding the animals.

供給動物食物。

But also I inevitably end up

但，最後，無可避免地，

thinking about what a masterpiece they are,

我會想著它們是多出色的傑作，

finely tuned by millions of years of evolution.

經過數百萬年演化 而做了精細的調整。

With 2,000 genes,

它們有兩千個基因，

they can do what all of our human ingenuity

它們能做到所有人類的足智多謀

has not figured out how to do yet.

都尚未想通要如何做的事。

They can take solar energy, CO2

它們能取得太陽能、二氧化碳，

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

將之轉換成化學能， 以有機碳的形式呈現，

locking that sunlight in those carbon bonds.

把太陽光鎖入那些碳鍵當中。

If we could figure out exactly how they do this,

如果我們能搞懂它們是怎麼辦到的，

it could inspire designs

就可以促成新的設計，

that could reduce our dependency on fossil fuels,

來減少我們對化石燃料的依賴，

which brings my story full circle.

這樣我的故事就成了 完整的圓，回到開頭了。

The fossil fuels that are buried that we're burning

被掩埋的化石燃料， 我們在燒的化石燃料，

took millions of years for the earth to bury those,

地球花了數百萬年的時間來掩埋它們，

including those ancestors of Prochlorococcus,

包括原綠球藻的那些祖先，

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

現在我們一貶眼就把它們燃燒光了，

on geological timescales.

就地質學的時間線來說是一貶眼。

Carbon dioxide is increasing in the atmosphere.

大氣中的二氧化碳在增加。

It's a greenhouse gas.

它是種溫室氣體。

The oceans are starting to warm.

海洋開始暖化。

So the question is, what is that going to do

所以，問題是，

for my Prochlorococcus?

那和我的原綠球藻有什麼關係？

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

我相信你們預期我會說， 我親愛的微生物天數已盡，

but in fact they're not.

但，事實上，並不是。

Projections are that their populations will expand as the ocean warms

我們預測，隨海洋暖化， 它們的數量會再擴展，

to 30 percent larger by the year 2100.

到 2100 年時，會再多出 30%。

Does that make me happy?

那讓我很開心嗎？

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

嗯，我的確為原綠球藻感到開心——

(Laughter)

（笑聲）

but not for the planet.

但對地球並非好事。

There are winners and losers

在我們進行的這項全球實驗中，

in this global experiment that we've undertaken,

有贏家也有輸家，

and it's projected that among the losers

我們預測，輸家將會包括

will be some of those larger phytoplankton,

其中一些比較大的浮游植物，

those charismatic ones

迷人的那些，

which are expected to be reduced in numbers,

預期它們的數量會減少，

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

而它們是浮游動物的食物， 浮游動物又是魚類的食物，

that we like to harvest.

我們則要捕魚。

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

所以，在過去三十五年間， 原綠球藻一直都是我的靈感，

but there are legions of other microbes out there

但外頭還有許多其他的微生物，

maintaining our planet for us.

在為我們維護地球。

They're out there

它們就在那裏，

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

準備好等著我們去找到它們， 讓它們也能訴說它們的故事。

Thank you.

謝謝。

(Applause)

（掌聲）