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As we walk through our daily environments, we're surrounded by exotic creatures that are too small to see with the naked eye.
日常生活中我们被许多奇异的生物所环绕，它们小到我们用肉眼无法看到。
We usually imagine these microscopic organisms, or microbes, as asocial cells that float around by themselves.
我们通常把这些微型有机物或者说微生物想象成独自四处漂流、不合群的细胞体。
But in reality, microbes gather by the millions to form vast communities known as biofilms.
但实际上，微生物以数百万计地聚集，形成一种叫做生物膜的巨大组织。
Natural biofilms are like miniature jungles filled with many kinds of microbes from across the web of life.
天然的生物膜就像微缩丛林，充满了来自生命之网的各种微生物。
Bacteria and archaea mingle with other microbes like algae, fungi, and protozoa,
海藻、真菌、原生动物等微生物与细菌、古生菌混合，
forming dense, organized structures that grow on almost any surface.
形成紧密、有序的、能在几乎所有表面上生长的结构。
When you pad across a river bottom, touch the rind of an aged cheese,
当你踏过河底时，触摸陈年的奶酪表皮时，
tend your garden soil, or brush your teeth, you're coming into contact with these invisible ecosystems.
料理花园里的土壤时，或者刷牙时，你都在与这些看不见的生态系统发生接触。
To see how biofilms come about, let's watch one as it develops on a submerged river rock.
为了了解生物膜如何产生，我们以一个生长在河石上的生物膜为例。
This type of biofilm might begin with a few bacteria swimming through their liquid environment.
这种生物膜最初由少数细菌组成，这些细菌在周围的液体环境中穿梭。
The cells use rotating flagella to propel towards the surface of the rock,
细胞利用旋转的鞭毛游向石头的表面，
which they attach to with the help of sticky appendages.
然后利用富有粘性的附属物附着于石头上。
Then, they start producing an extracellular matrix that holds them together as they divide and reproduce.
其后，细胞开始制造细胞外基质，细胞分裂、繁殖时，细胞外基质能够保持细胞的完整。
Before long, microcolonies arise, clusters of cells sheathed in this slimy, glue-like material.
不久后小菌落形成了，成群的细胞在这种黏滑、胶状的小菌落里生活。
Microcolonies grow to become towers, while water channels flow around them, functioning like a basic circulatory system.
小菌落渐渐长成塔状，水分子通过水通道进入细胞，功能相当于一个基本的循环系统。
But why do microbes build such complex communities when they could live alone?
微生物能够独立生存，那么为什么它们还要建立起如此复杂的群落呢？
For one thing, microbes living in a biofilm are rooted in a relatively stable microenvironment
一方面，对于微生物而言，生物膜形成的微观环境相对稳定，
where they may have access to a nutrient source. There's also safety in numbers.
在此微生物拥有营养来源。另一方面，集体生活也更加安全。
Out in the deep, dark wilderness of the microbial world, isolated microbes face serious risks.
微生物世界黑暗而原始，单独行动非常危险。
Predators want to eat them, immune systems seek to destroy them,
它们可能会被掠食者捕杀，被免疫系统毁灭，
and there are physical dangers, too, like running out of water and drying up.
另外还有很多肉体风险，比如失水干涸而死。
However, in a biofilm, the extracellular matrix shields microbes from external threats.
但是，如果生活在生物膜中，细胞外基质能够为微生物提供保护。
Biofilms also enable interactions between individual cells.
微生物在生物膜中还可以与其他微生物互动。
When microbes are packed against each other in close proximity,
当微生物紧密聚集在一起时，
they can communicate, exchange genetic information, and engage in cooperative and competitive social behaviors.
它们就能够沟通，交换遗传信息，并产生社会性行为，与同类合作或竞争。
Take the soil in your garden, home to thousands of bacterial species.
你从花园里带走的一小块泥土就是上千种细菌的居所。
As one species colonizes a plant root,
当一种细菌殖居于一株植物的根部时，
its individual cells might differentiate into various subpopulations, each carrying out a specific task.
其个别细胞可能分化成不同的次级种群，每一种群执行各自的特定任务。
Matrix producers pump out the extracellular goo,
基质制造者能够分泌细胞外粘性物质，
swimmers assemble flagella and are free to move about or migrate,
鞭毛可以自由活动和迁移，
and spore-formers produce dormant, tough endospores that survive starvation, temperature extremes, and harmful radiation.
芽孢菌生产休眠、坚硬的孢子内壁，孢子内壁能够在饥饿、极端温度以及有害射线下生存。
This phenomenon is called division of labor.
这种现象称之为分工。
Ultimately, it gives rise to a sophisticated system of cooperation
最终形成一个复杂、精致的合作系统，
that's somewhat like a multicellular organism in itself.
有些类似于多细胞生物。
But because biofilms often contain many different microbes
但是，生物膜常常包含不同种类的微生物，
that aren't closely related to each other, interactions can also be competitive.
它们之间关联并不紧密，有时会互相竞争。
Bacteria launch vicious attacks on their competitors by secreting chemicals into the environment,
细菌会对竞争者发起猛烈攻击，在周围环境中分泌化学物质，
or by deploying molecular spears to inject nearby cells with toxins that literally blow them up.
或利用分子茅刺将毒素注射到临近细胞，将它们涨破。
In the end, competition is all about resources.
归根结底，竞争是为了资源。
If one species eliminates another, it keeps more space and food for itself.
如果一种细菌消灭了另一种细菌，那么它就将拥有更多的空间和食物。
Although this dramatic life cycle occurs beyond the limits of our vision,
虽然这种奇妙的生命系统超出我们的目力所及，
microbial communities provide humans and other species with tangible, and sometimes even delicious, benefits.
但微生物群落为人类和其他物种提供了有形的益处，有时这种益处甚至非常美味。
Microbes make up a major fraction of the biomass on Earth
微生物是地球生物量的一个主要的组成部分，
and play a critical role within the global ecosystem that supports all larger organisms, including us.
并且它们在全球生态系统中扮演着重要角色，供养所有大型生物，也包括人类。
They produce much of the oxygen we breath,
它们制造了大量我们呼吸的空气，
and are recruited to clean up environmental pollution, like oil spills, or to treat our waste water.
还能用来应对石油泄漏等环境污染问题，或者用来处理污水。
Not to mention, biofilms are normal and flavor enhancing parts of many of the foods we enjoy, including cheese, salami, and kombucha.
更不用说，我们享用的许多美食也需要生物膜的参与，包括奶酪、意大利香肠以及红茶菌。
So the next time you brush your teeth, bite into that cheese rind, sift through garden soil,
所以，下次你刷牙咬破乳酪外皮，踏上花园的土壤
or skip a river stone, look as close as you can.
或者打水漂时，尽可能地仔细看看。
Imagine the microbial jungles all around you waiting to be discovered and explored.
想象一下围绕着你的微生物丛林，正等待被发现和探索。
