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  • 细菌分类

    Microscopic view of bacteria with various shapes and structures in a blue environment.

    With so many different bacteria, how are they all classified?
    ::这么多不同的细菌 如何分类?

    By shape? By size? By some other criteria? As you can imagine, classifying is probably not an easy task. Bacteria are classified by their traits, some of which have to do with their shape, others with the cell wall , and even additional traits.
    ::以形状划分大小? 以大小划分? 以其他标准划分? 正如您可以想象的那样, 分类可能并非易事。 细菌按其特性分类,其中一些与形状有关,另一些与细胞墙有关,甚至与其他特性有关。

    The Prokaryotic Domains
    ::Prokaryatlogy 域域

    Domain Bacteria
    ::域细菌a

    Bacteria are the most diverse and abundant group of organisms on Earth. They live in almost all environments. They are found in the ocean, the soil , and the intestines of . They are even found in rocks deep below Earth’s surface. Any surface that has not been sterilized is likely to be covered with bacteria. The total number of bacteria in the world is amazing. It’s estimated to be 5 × 10 30 , or five million trillion. You have more bacteria in and on your body than you have body cells!
    ::细菌是地球上最多样和最丰富的生物群。 它们几乎生活在所有环境中。 它们存在于海洋、土壤和肠中。 它们甚至存在于地表深处的岩石中。 任何未绝育的表面都有可能被细菌覆盖。 世界上细菌的总数是惊人的。 据估计,细菌的总数是5×1030, 或500万亿。 你体内和身体上的细菌比身体细胞还多!

    Bacteria called cyanobacteria are very important. They are bluish green in color (see Figure ) because they contain chlorophyll (but not , of course). They make food through and release oxygen into the air. These bacteria were probably responsible for adding oxygen to the air on early Earth. This changed the planet’s atmosphere . It also changed the direction of evolution. Ancient cyanobacteria also may have evolved into the chloroplasts of plant .
    ::细菌叫做蓝菌细菌,非常重要。它们颜色是紫绿的(见图 ) , 因为它们含有叶绿素(但当然不是 ) 。 它们制造食物并释放氧气到空气中。 这些细菌可能是早期地球空气中增加氧气的原因。 这改变了地球的大气。 它也改变了进化方向。 古代蓝菌也可能演变成植物的叶板。

    Aerial view of a lake showing green cyanobacteria blooms caused by nutrient overgrowth.

    Cyanobacteria Bloom. The green streaks in this lake consist of trillions of cyanobacteria. Excessive nutrients in the water led to overgrowth of the bacteria.
    ::这个湖的绿线由数万亿的蓝线构成 水中的过量养分导致细菌的过度生长

    Thousands of of bacteria have been discovered, and many more are thought to exist. The known species can be classified on the basis of various traits. One is based on differences in their cell walls and outer membranes. It groups bacteria into Gram-positive and Gram-negative bacteria, as described in Figure .
    ::已知的物种可以根据不同的特性进行分类,其中之一是细胞壁和外膜的差别,如图1所示,将细菌分类为格列阳性和格列阴性细菌。

    Cyanobacteria bloom in a lake showing excessive growth due to nutrient overload.

    Classification of Bacteria. Different types of bacteria stain a different color when stained with Gram stain. This makes them easy to identify.
    ::细菌分类:不同类型的细菌与克拉姆染色时染色不同,因此很容易识别。

    Domain Archaea
    ::域名 Archaea

    Scientists still know relatively little about . This is partly because they are hard to grow in the lab. Many live inside the bodies of animals, including humans. However, none are known for certain to cause disease.
    ::科学家对这个研究仍知之甚少。这在一定程度上是因为他们很难在实验室中生长。许多人生活在动物体内,包括人类在内。然而,据知没有哪一种疾病是已知的。

    Archaea were first discovered in extreme environments. For example, some were found in hot springs. Others were found around deep sea vents. Such Archaea are called extremophiles , or “lovers of extremes.” Figure describes three different types of Archaean extremophiles. The places where some of them live are thought to be similar to the environment on ancient Earth. This suggests that they may have evolved very early in Earth’s history.
    ::Archaea最初是在极端环境中发现的,例如,有些是在温泉中发现的,另一些是在深海喷口附近发现的。 此类Archaea被称作极端嗜血动物或“极端爱好者 ” 。 图中描述了三种不同的Archaean 极端嗜血动物。 其中一些人居住的地方被认为与古代地球的环境相似。 这表明他们可能在地球历史上很早就进化了。

    Three types of Archaean extremophiles: halophiles, hyperthermophiles, and acidophiles in unique environments.

    Extremophile Archaea. Many Archaea are specialized to live in extreme environments. Just three types are described here.
    ::许多Archaea专门生活在极端环境中,这里仅描述三种类型。

    Archaea are now known to live just about everywhere on Earth. They are particularly numerous in the ocean. Archaea in plankton may be one of the most abundant types of organisms on the planet. Archaea are also thought to play important roles in the carbon and nitrogen cycles. For these reasons, Archaea are now recognized as a major aspect of life on Earth.
    ::Archaea现在被公认为生活在地球上的任何地方,在海洋中特别多。浮游生物中的Archaea可能是地球上最丰富的生物种类之一。Archaea也被认为在碳和氮循环中发挥了重要作用。因此,Archaea现在被公认为地球上生命的一个主要方面。

       

     

     

     

    Science Friday : Subvisual Subway: The Art of New York City's Bacterial World
    ::科学 星期五: 亚可视地铁:纽约市细菌世界的艺术

    An urban legend states that "using the handrails on the subway is like shaking hands with 100 people." In this video by Science Friday , Craig Ward sampled the bacteria on subway lines around New York City to create striking and unconventional "portraits" of NYC commuters.
    ::一位城市传奇人物指出,“在地铁上使用扶手就像与100人握手一样。 ”在这个由科学星期五拍摄的视频中,克雷格·沃德在纽约市周围的地铁线上采样了细菌,制造了纽约市通勤者的惊人和非常规的“肖像 ” 。

     

    Science Friday: Dawn of the Cyborg Bacteria
    ::科学周五: 赛博尔格细菌黎明

    Does using bacteria to power microscopic robots sound like a horror film? In this video by Science Friday, Ph.D. students Elizabeth Beattie and Denise Wong hope these nano bio-robots will provide a platform for future medical and micro-engineering endeavors.
    ::利用细菌给微型机器人提供动力是否听起来像一部恐怖片?在这个视频中,科学周五、博士生伊丽莎白·贝蒂和丹妮丝·黄(Denise Wong)希望这些纳米生物机器人能为未来的医学和微工程工作提供一个平台。

     

     

    Summary
    ::摘要

    • Bacteria live in virtually all environments on Earth.
      ::细菌几乎生活在地球上的所有环境中。
    • Archaea live everywhere on Earth, including extreme environments.
      ::Archaea生活在地球上的任何地方,包括极端环境。

    Review
    ::回顾

    1. Distinguish between Gram-positive and Gram-negative bacteria, and give an example of each.
      ::区分格外阳性和格外阴性细菌,并举例说明每一种细菌。
    2. Summarize the evolutionary significance of cyanobacteria.
      ::概述氰化物的进化意义。
    3. What are extremophiles? Name three types.
      ::什么是极端嗜血症?
    4. Describe the habitat of extreme halophiles.
      ::描述极端嗜血动物的栖息地。