VOA慢速英语2020--科学家发现吃塑料的细菌

Researchers have identified a new bacterium¹ that feeds on polyurethane, a kind of plastic that is difficult to recycle or destroy.

Scientists say the discovery could help reduce a flood of hard-to-recycle plastics that are ending up in the world's landfills and polluting oceans.

A team from the Helmholtz Center for Environmental Research in Leipzig, Germany, found the new strain of soil bacteria. It was identified in an area that contained a large amount of plastic waste.

The team discovered the bacteria were feeding on polyurethane diol, a substance widely used in many different products.

The researchers estimated that in 2015, polyurethane made up 3.5 million tons of Europe's plastics.

One problem is that recycling polyurethane requires a lot of energy. The plastic material does not melt when heated. Most polyurethane-based products end up in landfills, where they can release dangerous chemicals.

The team found that the bacterium, identified as Pseudomonas putida, can produce enzymes² that eat away at polyurethanes. This would make it possible to break down the material in the environment.

The results were recently reported in a study in the publication Frontiers in Microbiology.

Hermann Heipieper helped write the report. He said in a statement the finding "represents an important step in being able to reuse hard-to-recycle (polyurethane) products."

The research is part of a European Union program that seeks to find useful microorganisms. The goal is to identify living things that can help turn oil-based plastics into substances that can be broken down biologically.

Similar experiments have been carried out in the past.

In 2011, Yale University students discovered a fungus⁴ that could feed on polyurethane plastic even in a place without air, like at the bottom of a landfill.

Since then, scientists around the world have identified other kinds of fungi⁵ that can break down polyurethane. In 2017, a team of scientists identified a fungus that can feed on plastic by breaking down the main chemicals holding it together.

The German study noted⁶ that plastic-eating bacteria could be easily controlled and produced for industrial use. The researchers said the next step is to identify more information about the bacterial⁷ enzymes that can break down polyurethane.

Some scientists advise against introducing man-made enzymes or microorganisms into the environment that could be harmful.

Scientist Douglas Rader wrote about the issue in a 2018 article for the Environmental Defense⁸ Fund. He said much more study should be carried out to learn about "the complex relationships between plastics and marine⁹ ecosystems¹⁰." Such research is needed "before we can take drastic action such as" putting plastic-eating bacteria into the ocean, Rader wrote.

The group Plastic Oceans International reports that scientists estimate more than 8 million tons of plastic are thrown into the world's oceans every year.

An estimated 300 million tons of plastic is produced yearly worldwide. Plastic Oceans International says about half of that amount is created for one use only.

Words in This Story

recycle –v. to reuse something that has been used before often in another way

strain – n. a type of disease or plant

enzyme³ – n. a chemical substance produced by living cells that makes particular chemical reactions happen in animals and plants

fungus– n. a type of plant without leaves that gets its food from other living or decaying things

ecosystem¹¹ – n. a biological community of interacting organisms and their physical environment

drastic – adj. sudden or extreme

1 bacterium   

n.(pl.)bacteria 细菌

参考例句：

• The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
• A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。

2 enzymes   

n. 酶，酵素

参考例句：

• It was said that washing powders containing enzymes remove stains more efficiently. 据说加酶洗衣粉除污更有效。
• Among the enzymes which are particularly effective are pepsin, papain. 在酶当中特别有效的是胃朊酶、木瓜酶。

3 enzyme   

n.酵素，酶

参考例句：

• Above a certain temperature,the enzyme molecule will become unfolded.超过一定温度，酶分子将会展开。
• An enzyme that dissolves the fibrin of blood clots.能溶解血凝块中的纤维的酶。

4 fungus   

n.真菌，真菌类植物

参考例句：

• Mushrooms are a type of fungus.蘑菇是一种真菌。
• This fungus can just be detected by the unaided eye.这种真菌只用肉眼就能检查出。

5 fungi   

n.真菌，霉菌

参考例句：

• Students practice to apply the study of genetics to multicellular plants and fungi.学生们练习把基因学应用到多细胞植物和真菌中。
• The lawn was covered with fungi.草地上到处都是蘑菇。

6 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

7 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。

8 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

9 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

10 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

11 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。