The smallest solution to one of our biggest problems - Tierney Thys & Christian Sardet

翻译人员: Siyu Lian 校对人员: Yip Yan Yeung

At this very moment, almost everything around you is being eaten.

此时此刻，几乎所有 你身边的东西都在被吃掉。

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

人眼不可见的微生物 聚集在各个角落，

Hordes of bacteria, archaea, and fungi have evolved to produce powerful enzymes

成群的细菌、古菌和真菌已经 进化到可以产生强大的酶，

that break down tough organic material into digestible nutrients.

能够将坚韧的有机物转化为 可消化的营养物质。

But there’s one particularly widespread type of material

但有一种极为常见的材料

that almost no microbes can biodegrade:

几乎没有微生物可以降解：

plastics.

塑料。

To make most plastics, molecules from oil, gas and coal are refined

大多数塑料是由来自石油、 天然气和煤炭的分子经过提炼

and turned into long, repeating chains called polymers.

变成被称为聚合物的长链制成的。

This process often requires temperatures above 100˚C, incredibly high pressure,

这个过程通常需要高于 100 摄氏度的温度、

and various chemical modifications.

极高的压力和各种化学改造。

The resulting man-made polymers are quite different

由此产生的人造聚合物与

from the polymers found in nature.

大自然中的聚合物相当不同。

And since they’ve only been around since the 1950s,

由于塑料在 1950 年才出现，

most microbes haven’t had time to evolve enzymes to digest them.

大部分微生物还没有进化出 可以降解塑料的酶。

Making matters even more difficult,

更加难办的是，

breaking most plastics’ chemical bonds requires high temperatures

破坏大多数塑料的化学键需要

comparable to those used to create them—

与制成它们所用温度相当的高温，

and such heat is deadly to most microbes.

但这样的高温对大多数 微生物来说是致命的。

This means that most plastics never biologically degrade—

这代表了大多数塑料永远 不会被生物降解，

they just turn into countless, tiny, indigestible pieces.

它们只是变成了无数个 无法消化的小碎片。

And pieces from the most common plastics like Polyethylene, Polypropylene,

这些来自常见塑料的碎片， 像是聚乙烯、聚丙烯和

and Polyester-terephthalate have been piling up for decades.

聚对苯二甲酸乙二酯（PET） 几十年来一直堆积着。

Each year humanity produces roughly 400 million more tons of plastic,

每一年人类产生大约 4 亿多吨的塑料，

80% of which is discarded as trash.

其中 80% 被作为垃圾丢弃。

Of that plastic waste, only 10% is recycled.

在所有的塑料垃圾里， 只有 10% 被回收，

60% gets incinerated or goes into the landfills,

60% 的垃圾被焚烧 或进入垃圾填埋场，

and 30% leaks out into the environment

还有 30% 泄漏到环境中

where it will pollute natural ecosystems for centuries.

并污染了自然生态系统 长达几个世纪之久。

An estimated 10 million tons of plastic waste end up in the ocean each year,

每年预计有 1000 万吨 塑料垃圾最终流入海洋，

mostly in the form of microplastic fragments that pollute the food chain.

大多数以微塑料碎片的形态 污染食物链。

Fortunately, there are microbes that may be able

幸运的是，可能有微生物能够

to take a bite out of this growing problem.

“吃”掉一部分 这个日益严重的塑料问题。

In 2016, a team of Japanese researchers sampling sludge

2016 年，一个日本研究小组

at a plastic-bottle recycling plant discovered

在一家塑料瓶回收站 对沉积物进行采样，

Ideonella sakaiensis 201-F6.

他们发现了大阪堺菌 （Ideonella sakaiensis 201-F6）。

This never-before-identified bacterium contained two enzymes

这个前所未见的细菌

capable of slowly breaking down PET polymers

拥有两种可以在相对低温下

at relatively low temperatures.

缓慢破坏PET聚合物的酶。

Researchers isolated the genes coding for these plastic-digesting enzymes,

研究人员分离出了这些 消化塑料酶的基因代码，

allowing other bioengineers to combine and improve the pair—

使其他生物工程家能够 结合并改进这对酶，

creating super-enzymes that could break down PET up to 6 times faster.

从而创造出可以将PET分解 速度提高 6 倍的超级酶。

Even with this boost,

即使有了这样的增强，

these lab-grown enzymes still took weeks to degrade a thin film of PET,

这些实验室培养的酶降解一层 薄薄的PET膜仍需数周，

and they operated best at temperatures below 40˚C.

它们在低于 40˚C 的温度下 工作效果最好。

However, another group of scientists in Japan had been researching

日本的另一组科学家们一直

bacterial enzymes adapted to high temperature environments

在研究让细菌酶适应高温环境，

like compost piles.

如堆肥。

And within one particularly warm pile of rotting leaves and branches,

在一堆特别暖和的腐烂 树叶和树枝中，

they found gene sequences for powerful degrading enzymes

他们发现了拥有强大 降解能力酶的基因代码，

known as Leaf Branch Compost Cutinases.

被称作叶枝复合肥切割酶 （Leaf Branch Compost Cutinases）。

Using fast-growing microorganisms,

利用快速生长的微生物，

other researchers were able to genetically engineer

其他研究人员能够使用基因工程

high quantities of these enzymes.

来产生高数量的酶。

They then enhanced and selected special variants of the Cutinases

他们加强并选择能够在温度 达到 70˚C 的环境中

that could degrade PET plastic in environments reaching 70˚C—

降解PET塑料的特殊变种 角蛋白酶。

a high temperature that can weaken PET polymers and make them digestible.

这样的高温能够削弱PET聚合物 并让它们能够被降解。

With the help of these and other tiny diehards,

有这些和其他小强硬派的帮助，

the future of PET recycling looks promising.

回收PET的未来变得充满希望。

But PET is just one type of plastic.

但PET只是塑料的一类，

We still need ways to biologically degrade all the other types,

我们还需要找到其他办法来 生物降解所有类型的塑料，

including abundant PEs and PPs

包括大量的PE和PP，

which only begin breaking down at temperatures well above 130˚C.

它们在高达 130˚C 以上的温度才开始瓦解。

Researchers don’t currently know of any microbes or enzymes

研究人员现在还没有找到任何

tough enough to tolerate such temperatures.

强大到可以忍耐如此 高温的微生物或酶。

So for now, the main way we deal with these plastics

所以现在我们处理 这些塑料的主要方式是

is through energy-intensive physical and chemical processes.

通过高耗能的物理和化学手段。

Today only a small fraction of plasticwaste

目前只有很小一部分的塑料垃圾

can be biologically degraded by microbes.

可以被微生物生物降解。

Researchers are looking for more heat-tolerant plastivores

研究人员正在地球最恶劣的环境中

in the planet’s most hostile environments

寻找更多耐高温的食塑料者，

and engineering better plastivorous enzymes in the lab.

并在实验室中研制出 更好的食塑料酶。

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

但我们不能单单依靠这些小助手 来清理我们庞大的垃圾堆。

We need to completely rethink our relationship with plastics,

我们需要重新思考 我们和塑料的关系，

make better use of existing plastics,

更好地使用已经存在的塑料，

and stopproducing more of the same.

并停止生产更多已有的塑料制品。

And we urgently need to design more environmentally friendly types of polymers

我们急需设计出更好的， 对环境无害的聚合物，

that our growing entourage of plastivores can easily break down.

让我们持续壮大的食塑料酶 伙伴可以轻松地分解它们。