Part 1

The Bacteria Book

《细菌书》

Introduction Looking into a microscope is like peering into an alien world, one full of peculiar, pulsating creatures that act and move in strange ways. These mysterious microbes are absolutely everywhere—around you, on you, and inside you. We live in harmony with some of them, and we're at war with the rest. Some of the creatures you'll find in this book are gross and terrifying, while others are simply amazing. Get ready to discover the bacteria that makes you fart, the mite that lives in your eyelashes, and the fungus that turns ants into zombies. The world of the very small is endlessly fascinating, and I've packed these pages full of my favorite bits. Enjoy! Steve Mould

引言 用显微镜观察就像窥探一个外星世界，那里满是奇特、活跃的小家伙，一举一动都怪兮兮的。 这些神秘的微生物无处不在——环绕着你，沾在你身上，还住在你身体里。 有些微生物和我们和谐共处，剩下的那些，我们就得和它们“打仗”啦。 这本书里的小家伙，有的恶心又吓人，有的却神奇得不得了。 准备好来认识这些奇妙小家伙吧：让你放屁的细菌，住在你睫毛里的螨虫，还有能把蚂蚁变成僵尸的真菌。 这个微小世界超级迷人，我把我最喜欢的有意思的内容都塞在这本书里啦。 快来开启阅读吧！ 史蒂夫·莫尔德

What is a microbe? A microorganism, or "microbe," is any living creature that is so small you can't see it with your eyes. The most common microbe is bacteria, which first appeared on Earth more than 3.6 billion years ago. Smaller than rice Just how small are these creatures? Zoom in three thousand times on a single grain of rice and you might start to see lots of little bacteria. Viruses, another type of microbe, are smaller still! One grain of rice is about (6 mm) 0.25 in long. There could be as many as one trillion species of microbe on Earth. ARE MICROBES REALLY ALIVE? Although they are tiny, yes! Scientists don't agree on what makes something alive, but all living things seem to share certain features, such as the ability to move and to grow. Viruses only have some of these features, however, so some people think they aren't alive. If you were a microbe... If you were shrunk down to the size of bacteria, a grain of rice would seem bigger than a mountain. That's how small microbes are. Can you imagine it?

什么是微生物？ 微生物，就是一类小到你用肉眼看不见的生物。 最常见的微生物就是细菌，它们早在36亿多年前就出现在地球上了。 比米粒还小 这些小家伙到底有多小呢？ 把一粒米粒放大三千倍，你就能看到许许多多细小的细菌了。 病毒是另一类微生物，个头比细菌还要小！ 一粒米粒大约长6毫米（0.25英寸）。 地球上的微生物种类可能多达一万亿种。 微生物真的是活的吗？ 虽然它们个头极小，但它们确实是活的！ 对于“什么才算活着”，科学家还没有统一结论，但所有生物都有一些共同特征，比如能运动、会生长。 不过病毒只具备部分特征，所以有些人认为病毒不是活的。 如果你变成微生物…… 如果你缩小到细菌那么大，一粒米粒看起来都比一座山还要大。 微生物就是这么小。 你能想象吗？

Meet the microbes Say "hello" to the smallest critters on Earth! Here are six of the most common types of microbe. These creatures are everywhere you look— even though you usually can't see them. Bacteria Bacteria are made of just one cell each, and they are the simplest cells on the planet. There are more bacteria on Earth than any other form of life. Viruses Viruses are the smallest microbes. They are so small, they live inside the cells of other creatures. Many scientists say viruses may not even be alive since they don't eat or grow. Algae Many algae are made of one cell each, but they are usually bigger than bacteria. Like plants, algae use a green chemical called chlorophyll to turn sunlight into useful energy. Fungi Fungi, such as mold, break down dead plants and animals to use as food. A fungus can be made of one cell or of lots of cells. Protozoa Protozoa are made of only one cell. These creatures behave a bit like animals—they move around and eat other living things. Archaea Archaea look a lot like bacteria, but they behave in different ways. They can survive in extreme environments, such as very hot places or strong acids.

认识微生物 来和地球上最小的小家伙们打个招呼吧！ 这里介绍六种最常见的微生物。 它们无处不在，只是你通常看不见它们而已。 细菌 每个细菌都只由一个细胞构成，是地球上最简单的细胞。 地球上细菌的数量比其他任何生命都要多。 病毒 病毒是最小的微生物。 它们太小了，只能生活在其他生物的细胞里。 很多科学家认为病毒甚至可能不是活物，因为它们既不进食也不生长。 藻类 很多藻类也只由一个细胞构成，但个头通常比细菌大。 和植物一样，藻类用一种叫叶绿素的绿色物质把阳光转化为可用的能量。 真菌 真菌（比如霉菌）会分解死亡的动植物，把它们当作食物。 真菌可以由一个细胞构成，也可以由很多细胞构成。 原生动物 原生动物只由一个细胞构成。 这些小家伙的行为有点像动物——它们会四处活动，还会捕食其他生物。 古菌 古菌看起来和细菌很像，但习性大不相同。 它们能在极端环境中生存，比如非常炎热的地方或者强酸环境里。

Seeing is believing Microbes are creatures we can't see with just our eyes, so how do we know they exist? One way is by looking through a microscope—but this isn't the only way. Microscope This tool uses curved glass lenses to make things look bigger and clearer. You can see something as small as a thousandth of a millimeter with a laboratory microscope. We dye bacteria colors like violet or red to make them easier to see under a microscope. Electron microscope Some microbes, such as viruses, are too small to be seen with a regular microscope. Scientists use a special tool called an electron microscope to fire tiny particles called electrons at the virus. The electrons help make a computer picture. Colored pictures Pictures made using an electron microscope are black-and-white. People add color to the images later to make them clearer. Growing blobs Scientists make bacteria grow on special plates called petri dishes filled with a nutrient-rich goop called agar. The nutrients in the agar help the bacteria grow. After some time, the bacteria blobs are big enough for us to see. Staphylococcus (staff-il-oh-CAWcuss) lives on most people's skin. This bacteria is usually harmless. Microbes that can make people sick are called germs.

眼见为实 微生物是肉眼看不见的，我们怎么知道它们存在呢？ 一种方法是用显微镜观察——但这不是唯一的方法。 显微镜 这个工具用弧形玻璃镜片放大物体，让我们看得更大更清楚。 用实验室显微镜，你能看到小到千分之一毫米的物体。 我们会把细菌染成紫色或红色，让它们在显微镜下更容易被看到。 电子显微镜 有些微生物，比如病毒，太小了，普通显微镜看不见。 科学家用一种叫电子显微镜的特殊工具，让叫做电子的微小粒子轰击病毒。 电子会帮助生成电脑图像。 上色图片 电子显微镜生成的图片原本是黑白的。 人们之后会给图像上色，让它们更容易辨认。 培养菌落 科学家把细菌放在特殊的培养皿里培养，培养皿里装满了富含营养的琼脂。 琼脂里的营养能帮助细菌生长。 过一段时间，细菌团就大到我们能直接看见了。 葡萄球菌（发音：staff-il-oh-CAW-cuss）就生活在大多数人的皮肤上。 这种细菌通常是无害的。 能让人生病的微生物叫做病菌。

All about cells When you think of living creatures, or organisms, you probably think of animals and plants, not microscopic blobs. But all living creatures have something in common, from the biggest mammal to the smallest bacteria: They are all made of cells. Animal cells Look at your skin under a microscope and you'll see it's made of cells. We don't think of them as being alive because they can't grow and reproduce on their own. The cells in your body work together to keep the whole organism alive. When a skin cell is separated from your body, it dies. It can no longer grow or reproduce. Skin cells work together to form a protective barrier for your body. The human body is made of about 30 trillion cells. Microbe cells These are bacteria cells. Unlike skin cells, they don't need to stick together to stay alive. If you remove one bacteria cell, it will keep growing and reproducing as long as it has enough nutrients. Bacteria and other microbe cells can live on their own. Parts of a cell Cells come in many shapes and sizes. Some have simple structures, and some are really complex. However, they all have three parts in common: DNA, cytoplasm, and a cell membrane. DNA is a big molecule that tells the cell how to grow and behave. Cytoplasm is a jelly-like substance that fills the inside of the cell. The cell membrane holds the cell together and lets chemicals in and out.

认识细胞 当你想到生物时，你多半会想到动物和植物，而非显微镜下的微小团块。 但所有生物都有一个共同点：大到最大的哺乳动物，小到最小的细菌，全都由细胞构成。 动物细胞 把你的皮肤放在显微镜下观察，就能看到它由细胞组成。 我们不会认为单个细胞是活的，因为它们没法独自生长繁殖。 你身体里的细胞共同协作，维持整个生命体的存活。 如果一个皮肤细胞脱离了你的身体，它就会死亡。 它再也没法生长或者繁殖了。 皮肤细胞共同协作，为你的身体形成一道保护屏障。 人体大约由30万亿个细胞组成。 微生物细胞 这些就是细菌细胞。 和皮肤细胞不同，它们不需要聚集在一起就能存活。 如果你分离出一个细菌细胞，只要养分充足，它就能继续生长繁殖。 细菌和其他微生物细胞可以独立生存。 细胞的结构 细胞有各种各样的形状和大小。 有些细胞结构简单，有些则非常复杂。 不过它们都有三个共同的组成部分：DNA、细胞质和细胞膜。 DNA是一种大分子，它指导细胞如何生长、如何活动。 细胞质是填充在细胞内部的果冻状物质。 细胞膜把细胞包裹起来，控制物质进出细胞。