听力文摘：论地球上最成功的物种

For many scientists, a species’ success is measured by sheer numbers. In that case, the most successful species known to man is a type of bacterium¹ known as S-A-R-11, or SAR-11 for short. Scientists estimate that there are two-hundred and forty times a billion billion billion SAR11 cells floating around in the oceans. Now that makes six-billion humans sound like a mere² handful.

对很多科学家来说，一个物种的成功完全取决于数量。如果是那样是话，为人类所知的最成功的物种就是一种简称“SAR-11”的细菌。科学家们估计海洋中的SAR11细胞的数量超过2 x 10的28次方个。那让60亿人类听起来屈指可数。

SAR11 bacteria are known for their ability to transform one substance into another, which is why they are such an important part of the Earth’s chemical cycles. Although scientists are still uncertain about SAR11′s specific role, it appears to produce carbon dioxide using the oxygen and carbon from organic matter that’s derived³ from photosynthesis⁴. Scientists speculate that SAR11 plays a major role in the way the ocean’s surface acts as a giant carbon pump that removes carbon dioxide from the atmosphere.

SAR11细菌以其转换物质的能力为人所知。而这也使得它们成为地球化学循环中重要的部分。尽管科学家不能确定SAR11的具体作用。但它似乎可以使来自于光合作用的氧气和有机物种的碳发生作用，产生二氧化碳。科学家推测SAR11在海洋表面扮演着重要的作用，作为一个巨大的碳泵移除空气中的二氧化碳。

The catch is that SAR11 is what is known as an uncultured organism, which means that scientists haven’t been able to cultivate it under laboratory conditions. This requires scientists to develop pretty indirect genetic⁵ methods just to be able to study SAR11 cultures. Now that this technology is available, scientists are sequencing the SAR11 genome in order to figure out exactly what kinds of carbon it uses, and why it’s so successful at ocean living.

但目前SAR11是为培养生物，也就是说科学家不能在实验室里培养出这种细菌。因此需要科学家们研制出间接遗传方法，来研究SAR11。既然这项技术可用，科学家为了弄清楚究竟SAR11用的是哪种碳以及为什么它会如此的成功在海洋中生活，正在排序它的基因组。

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 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

3 derived   

vi.起源；由来；衍生；导出v.得到( derive的过去式和过去分词 )；（从…中）得到获得；源于；（从…中）提取

参考例句：

• Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
• He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》

4 photosynthesis   

n.光合作用

参考例句：

• In apple trees photosynthesis occurs almost exclusively in the leaves.苹果树的光合作用几乎只发生在叶内。
• Chloroplasts are the structures in which photosynthesis happens.叶绿体就是光合作用发生的地方。

5 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。