Invisible to the naked eye, organisms called microbes swarm every surface.

肉眼看不見的微生物遍佈所有物體表面。

Hordes of bacteria, archaea, and fungi have evolved to produce powerful enzymes that break down tough organic material into digestible nutrients.

大量的細菌、古菌和真菌，已經進化到能產出強大的酵素， 可分解結實的有機物， 將其轉化為可被消化的營養。

But there's one particularly widespread type of material that almost no microbes can biodegrade: plastics.

但幾乎沒有微生物可生物分解某種隨處可見的物質： 塑膠。

To make most plastics, molecules from oil, gas and coal are refined and turned into long, repeating chains called polymers.

為了製造大部分的塑膠， 我們提煉石油、天然氣和煤炭的分子，將其重新排列，製成又長又重複的連結，稱為聚合物。

This process often requires temperatures above 100 degree Celsius, incredibly high pressure, and various chemical modifications.

這個過程通常需要攝氏 100 度以上的溫度、驚人的高壓，以及各種化學改質。

The resulting man-made polymers are quite different from the polymers found in nature.

這種人工製造的聚合物，和天然聚合物相當不同。

And since they've only been around since the 1950s, most microbes haven't had time to evolve enzymes to digest them.

因為它們在 1950 年代才出現，大多數的微生物還沒有足夠的時間， 進化出可分解塑膠的酵素。

Making matters even more difficult, breaking most plastics' chemical bonds requires high temperatures comparable to those used to create theM, and such heat is deadly to most microbes.

讓事態更難以收拾的是，想分解塑膠的化學鍵， 需要和製造塑膠時差不多的高溫， 而絕大多數的微生物都無法在這種溫度下生存。

This means that most plastics never biologically degrade.

意味著大多數的塑膠都不可能被生物分解。

They just turn into countless, tiny, indigestible pieces.

只能成為無數細小、不可分解的碎片。

And pieces from the most common plastics like Polyethylene, Polypropylene, and Polyester-terephthalate have been piling up for decades.

而最常見的塑膠製品， 如聚乙烯、聚丙烯，和聚酯對苯二甲酸酯的碎片， 已經堆積了數十年。

Each year humanity produces roughly 400 million more tons of plastic, 80% of which is discarded as trash.

我們每年約會製造四億多噸的塑膠，其中有 80% 都被當成垃圾丟棄。

Of that plastic waste, only 10% is recycled.

只有一成的塑膠垃圾會被回收。

60% gets incinerated or goes into the landfills, and 30% leaks out into the environment where it will pollute natural ecosystems for centuries.

六成的垃圾會被焚燒或掩埋，三成則會流入環境， 汙染自然生態系統長達數百年。

An estimated 10 million tons of plastic waste end up in the ocean each year, mostly in the form of microplastic fragments that pollute the food chain.

據估計，每年約有一千萬噸的塑膠垃圾流入海洋，大多數都成了汙染食物鏈的塑膠微粒。

Fortunately, there are microbes that may be able to take a bite out of this growing problem.

幸運的是，我們現在已發現也許能將日益嚴重的塑膠危機分解的微生物。

In 2016, a team of Japanese researchers sampling sludge at a plastic-bottle recycling plant discovered Ideonella sakaiensis 201-F6.

2016 年，一支日本研究團隊，至寶特瓶回收工廠取樣汙泥時， 發現了大阪堺菌 201-F6。

This never-before-identified bacterium contained two enzymes capable of slowly breaking down PET polymers at relatively low temperatures.

這個首次被發現的細菌含有兩種酵素，可在相對低溫的環境中， 緩慢分解 PET 塑膠聚合物。

Researchers isolated the genes coding for these plastic-digesting enzymes, allowing other bioengineers to combine and improve the pair, creating super-enzymes that could break down PET up to six times faster.

研究者將製造這種酵素的基因編碼分離， 讓其他生物工程師結合、 增強這兩種酵素，創造出能以六倍速分解塑膠的超級酵素。

Even with this boost, these lab-grown enzymes still took weeks to degrade a thin film of PET, and they operated best at temperatures below 40 degree Celsius.

雖然已經過改良， 這些實驗室培養的超級酵素仍需花費數週才能分解一片PET 薄膜， 且在低於攝氏 40 度時表現最佳。

However, another group of scientists in Japan had been researching bacterial enzymes adapted to high temperature environments like compost piles.

然而，另一個日本科學家團隊，長期研究細菌酵素， 例如堆肥對高溫環境的適應力。

And within one particularly warm pile of rotting leaves and branches, they found gene sequences for powerful degrading enzymes known as "Leaf Branch Compost Cutinases."

而在特別溫熱的一堆腐葉和樹枝中，他們發現了一組能製造強大分解酵素的基因序列， 也就是「葉枝堆肥角質酶」。

Using fast-growing microorganisms, other researchers were able to genetically engineer high quantities of these enzymes.

利用快速生長的微生物，其他研究者也能利用基因工程， 培養出大量這種酵素。

They then enhanced and selected special variants of the Cutinases that could degrade PET plastic in environments reaching 70 degree Celsius, a high temperature that can weaken PET polymers and make them digestible.

接著，他們增強並選擇一種特定的角質酶變體，它能在攝氏 70 度下 分解 PET 塑膠， 這種溫度可軟化 PET 塑膠， 讓它們更易分解。

With the help of these and other tiny diehards, the future of PET recycling looks promising.

有了這些細菌的幫助，回收 PET 塑膠看似前景可期。

But PET is just one type of plastic.

但 PET 只是一種塑膠。

We still need ways to biologically degrade all the other types, including abundant PEs and PPs, which only begin breaking down at temperatures well above 130 degree Celsius.

我們仍需要找到能夠生物分解 其他的塑膠的方法，其中包含大量的聚苯醚碸和聚苯硫醚， 它們要在攝氏 130 度 以上才能被分解。

Researchers don't currently know of any microbes or enzymes tough enough to tolerate such temperatures.

研究者現在仍未發現任何能忍受這種高溫的微生物或酵素。

So for now, the main way we deal with these plastics is through energy-intensive physical and chemical processes.

所以，我們現在處理這些塑膠的主要方法，是高能量的物理和化學過程。

Today only a small fraction of plasticwaste can be biologically degraded by microbes.

今天，只有一小部分的塑膠垃圾，可被微生物生物分解。

Researchers are looking for more heat-tolerant plastivores in the planet's most hostile environments and engineering better plastivorous enzymes in the lab.

研究者還在地球最惡劣的環境中，尋找更多能耐高熱、 可分解塑膠的微生物， 並在實驗室中，以基因改造做出更優秀的塑膠分解酵素。

But we can't rely solely on these tiny helpers to clean up our enormous mess.

但我們不能只靠這些小幫手清理我們製造出的巨量垃圾。

We need to completely rethink our relationship with plastics, make better use of existing plastics, and stop producing more of the same.

我們必須從頭反省我們和塑膠的關係，更完善地利用已存的塑膠產品， 並不再製造更多塑膠產品。

And we urgently need to design more environmentally-friendly types of polymers that our growing entourage of plastivores can easily break down.

我們也需要快點設計出對環境更友善的聚合物，讓不停增長的塑膠分解微生物， 可輕易將它們分解。