美国国家公共电台 NPR--Think all bacteria are microscopic? Tell that to these centimeter-long monsters

Think all bacteria are microscopic¹? Tell that to these centimeter-long monsters

Transcript²

Bacteria typically live out their teeny-tiny lives in the microscopic realm, but now scientists have found a gargantuan³ one the size and shape of a human eyelash.

The new find is "by far the largest bacteria known to date," says Jean-Marie Volland of Lawrence Berkeley National Laboratory and the Laboratory for Research in Complex Systems. "These bacteria are about 5,000 times larger than most bacteria."

"To put things into perspective," he added, "it is the equivalent for us humans to encounter another human who would be as tall as Mount Everest."

The roughly 1 centimeter behemoth somehow attaches itself to sunken leaves in Caribbean mangrove⁴ swamps, according to a report in the journal Science.

The scientist who initially⁵ collected the thin white filaments⁶ had no idea that he'd discovered a new kind of bacteria visible to the naked eye.

But a lab examination showed that they didn't have key features of plant or animal cells, and a genetic⁷ analysis soon revealed their true nature. They're related to other bacteria that also make a living off of sulfur⁸ and grow large — but not this large.

Now called Thiomargarita magnifica, these bacteria haven't yet been grown in the lab, so much about their lifestyle remains⁹ mysterious — including what advantage they get in their underwater environment by growing to such a stupendous size.

In addition to challenging old ideas about the maximum possible size, each of these bacteria organizes its innards in an unusually advanced way.

Instead of allowing genetic material to float around freely, like other bacteria do, these beings wrap it up and contain it within a kind of package. This is similar to what's done in more complex kinds of cells, like those that make up plants and animals.

Volland cautions that this doesn't mean these bacteria are some kind of "missing link" between simple forms of life and more complex ones, saying it's just a "fascinating example of a bacterium¹⁰ that has evolved a higher level of complexity¹¹."

Still, finding this inside bacteria, along with their amazing size, makes this "a truly magnificent find," according to Thijs Ettema, a microbiologist at Wageningen University & Research who was not part of this research team.

"The researchers have identified a real 'microbial monster,'" Ettema said in an email. "Their work underlines that the microbial world continues to amaze us!"

These bacteria can't even rightly be called microbes, because microbes are by definition microscopic, points out Petra Anne Levin of Washington University in St Louis, who wrote a commentary accompanying the new report.

What's more, while most bacteria reproduce by dividing into two identical cells, these long, filament-like creatures seem to reproduce by budding off one small piece at the tip that can then float away and go on to create a whole new being.

And even though these organisms are so big that hundreds of thousands of smaller bacteria could fit on their outside surfaces, researchers found that these surfaces look pristine¹², suggesting that these bacteria might secrete¹³ some kind of antibiotic¹⁴ to ward¹⁵ off smaller relatives.

Finding this bacterium "has really opened our eyes to the unexplored microbial diversity that exists," says Shailesh Date of the University of California, San Francisco, and the Laboratory for Research in Complex Systems. "Really we are just scratching the surface, and who knows what interesting things we have yet to discover."

1 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

2 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

3 gargantuan   

adj.巨大的，庞大的

参考例句：

• My gargantuan,pristine machine was good for writing papers and playing solitaire,and that was all.我那庞大的、早期的计算机只适合写文章和玩纸牌游戏，就这些。
• Right away,I realized this was a mistake of gargantuan proportions.我立刻意识到这是一个巨大的错误。

4 mangrove   

n.(植物)红树，红树林

参考例句：

• It is the world's largest tidal mangrove forest.它是世界上最大的红树林沼泽地。
• Many consider this the most beautiful mangrove forest in all Thailand.许多人认为这里是全泰国最美丽的红树林了。

5 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

6 filaments   

n.（电灯泡的）灯丝( filament的名词复数 )；丝极；细丝；丝状物

参考例句：

• Instead, sarcomere shortening occurs when the thin filaments'slide\" by the thick filaments. 此外，肌节的缩短发生于细肌丝沿粗肌丝“滑行”之际。 来自辞典例句
• Wetting-force data on filaments of any diameter and shape can easily obtained. 各种直径和形状的长丝的润湿力数据是易于测量的。 来自辞典例句

7 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

8 sulfur   

n.硫，硫磺（=sulphur）

参考例句：

• Sulfur emissions from steel mills become acid rain.炼钢厂排放出的硫形成了酸雨。
• Burning may produce sulfur oxides.燃烧可能会产生硫氧化物。

9 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

10 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。

11 complexity   

n.复杂(性)，复杂的事物

参考例句：

• Only now did he understand the full complexity of the problem.直到现在他才明白这一问题的全部复杂性。
• The complexity of the road map puzzled me.错综复杂的公路图把我搞糊涂了。

12 pristine   

adj.原来的，古时的，原始的，纯净的，无垢的

参考例句：

• He wiped his fingers on his pristine handkerchief.他用他那块洁净的手帕擦手指。
• He wasn't about to blemish that pristine record.他本不想去玷污那清白的过去。

13 secrete   

vt.分泌；隐匿，使隐秘

参考例句：

• The pores of your body secrete sweat.身上的毛孔分泌汗液。
• Squirrels secrete a supply of nuts for winter.松鼠为准备过冬而藏坚果。

14 antibiotic   

adj.抗菌的；n.抗生素

参考例句：

• The doctor said that I should take some antibiotic.医生说我应该服些用抗生素。
• Antibiotic can be used against infection.抗菌素可以用来防止感染。

15 ward   

n.守卫，监护，病房，行政区，由监护人或法院保护的人（尤指儿童）；vt.守护，躲开

参考例句：

• The hospital has a medical ward and a surgical ward.这家医院有内科病房和外科病房。
• During the evening picnic,I'll carry a torch to ward off the bugs.傍晚野餐时，我要点根火把，抵挡蚊虫。