微生物英语作文

⑹ 谁能帮我找一篇与微生物有关的英文文章``````

http://en.wikipedia.org/wiki/Microorganism
http://zh.wikipedia.org/wiki/%E5%BE%AE%E7%94%9F%E7%89%A9

A microorganism (also can be spelled as micro organism) or microbe is an organism that is microscopic (too small to be seen by the naked human eye). The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design.

Microorganisms are incredibly diverse and include bacteria, fungi, archaea, and protists, as well as some microscopic plants and animals such as plankton, and popularly-known animals such as the planarian and the amoeba. They do not include viruses and prions, which are generally classified as non-living. Most microorganisms are single-celled, or unicellular, but some multicellular organisms are microscopic, while some unicellular protists, and a bacteria called Thiomargarita namibiensis are visible to the naked eye.

Microorganisms live in all parts of the biosphere where there is liquid water, including hot springs, on the ocean floor, high in the atmosphere and deep inside rocks within the Earth's crust. Microorganisms are critical to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle, and recent studies indicate that airborne microbes may play a role in precipitation and weather.

Microbes are also exploited by people in biotechnology, both in traditional food and beverage preparation, as well as modern technologies based on genetic engineering. However, pathogenic microbes are harmful, since they invade and grow within other organisms, causing diseases that kill millions of people, other animals, and plants.

History
Evolution
Single-celled microorganisms were the first forms of life to develop on earth, approximately 3– billion years ago.Further evolution was slow,and for about 3 billion years in the Precambrian eon, all organisms were microscopic. So, for most of the history of life on Earth the only form of life were microorganisms.Bacteria, algae and fungi have been identified in amber that is 220 million years old, which shows that the morphology of microorganisms has changed little since the triassic period.

Most microorganisms can reproce rapidly and microbes such as bacteria can also freely exchange genes by conjugation, transformation and transction between widely-divergent species.[10] This horizontal gene transfer, coupled with a high mutation rate and many other means of genetic variation, allows microorganisms to swiftly evolve (via natural selection) to survive in new environments and respond to environmental stresses. This rapid evolution is important in medicine, as it has led to the recent development of 'super-bugs' — pathogenic bacteria that are resistant to modern antibiotics.

Pre-Microbiology
The possibility that microorganisms might exist was discussed for many centuries before their actual discovery in the 17th century. The first ideas about microorganisms were those of the Roman scholar Marcus Terentius Varro in a book titled On Agriculture in which he warns against locating a homestead near swamps:

“ …and because there are bred certain minute creatures which cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and there cause serious diseases.”

This passage seems to indicate that the ancients were aware of the possibility that diseases could be spread by yet unseen organisms.

In The Canon of Medicine (1020), Abū Alī ibn Sīnā (Avicenna) stated that bodily secretion is contaminated by foul foreign earthly bodies before being infected.He also hypothesized that tuberculosis and other diseases might be contagious, i.e. that they were infectious diseases, and used quarantine to limit their spread.

When the Black Death bubonic plague reached al-Andalus in the 14th century, Ibn Khatima wrote that infectious diseases were caused by "contagious entities" that enter the human body. Later, in 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances.

All these early claims about the existence of microorganisms were speculative in nature and not based on any data or science. Microorganisms were neither proven, observed, nor correctly and accurately described until the 17th century. The reason for this was that all these early inquiries lacked the most fundamental tool in order for microbiology and bacteriology to exist as a science, and that was the microscope.

Discovery
Anton van Leeuwenhoek was the first person to observe microorganisms, using a microscope of his own design, thereby making him the first microbiologist. In doing so Leeuwenhoek would make one of the most important contributions to biology and open up the fields of microbiology and bacteriology. Prior to Leeuwenhoek's discovery of microorganisms in 1675, it had been a mystery as to why grapes could be turned into wine, milk into cheese, or why food would spoil. Leeuwenhoek did not make the connection between these processes and microorganisms, but using a microscope, he did establish that there were forms of life that were not visible to the naked eye.Leeuwenhoek's discovery, along with subsequent observations by Lazzaro Spallanzani and Louis Pasteur, ended the long-held belief that life spontaneously appeared from non-living substances ring the process of spoilage.

Lazzarro Spallanzani found that microorganisms could only settle in a broth if the broth was exposed to the air. He also found that boiling the broth would sterilise it and kill the microorganisms. Louis Pasteur expanded upon Spallanzani's findings by exposing boiled broths to the air, in vessels that contained a filter to prevent all particles from passing through to the growth medium, and also in vessels with no filter at all, with air being admitted via a curved tube that would not allow st particles to come in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within the broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur's experiment. This meant that the living organisms that grew in such broths came from outside, as spores on st, rather than spontaneously generated within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and supported germ theory.

In 1876, Robert Koch established that microbes can cause disease. He did this by finding that the blood of cattle who were infected with anthrax always had large numbers of Bacillus anthracis. Koch also found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, causing the healthy animal to become sick. He also found that he could grow the bacteria in a nutrient broth, inject it into a healthy animal, and cause illness. Based upon these experiments, he devised criteria for establishing a causal link between a microbe and a disease in what are now known as Koch's postulates.Though these postulates cannot be applied in all cases, they do retain historical importance in the development of scientific thought and can still be used today.

Classification and structure
Microorganisms can be found almost anywhere in the taxonomic organization of life on the planet. Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic, including most protists, some fungi, as well as some animals and plants. Viruses are generally regarded as not living and therefore are not microbes, although the field of microbiology also encompasses the study of viruses.

[edit] Prokaryotes
Prokaryotes are organisms that lack a cell nucleus and the other organelles found in eukaryotes. Prokaryotes are almost always unicellular, although some species such as myxobacteria can aggregate into complex structures as part of their life cycle. These organisms are divided into two groups, the archaea and the bacteria.

Bacteria
Bacteria are the most diverse and abundant group of organisms on Earth. Bacteria inhabit practically all environments where some liquid water is available and the temperature is below +140 °C. They are found in sea water, soil, air, animals' gastrointestinal tracts, hot springs and even deep beneath the Earth's crust in rocks.[20] Practically all surfaces which have not been specially sterilized are covered in bacteria. The number of bacteria in the world is estimated to be around five million trillion trillion, or 5 × 1030.

Bacteria are practically all invisible to the naked eye, with a few extremely rare exceptions, such as Thiomargarita namibiensis.They are unicellular organisms and lack membrane-bound organelles. Their genome is usually a single loop of DNA, although they can also harbor small pieces of DNA called plasmids. These plasmids can be transferred between cells through bacterial conjugation. Bacteria are surrounded by a cell wall, which provides strength and rigidity to their cells. They reproce by binary fission or sometimes by budding, but do not undergo sexual reproction. Some species form extraordinarily resilient spores, but for bacteria this is a mechanism for survival, not reproction. Under optimal conditions bacteria can grow extremely rapidly and can double as quickly as every 10 minutes......

微生物是指一切肉眼看不到或看不清楚，因而需要借助显微镜观察的微小生物。微生物包括原核微生物（如细菌）、真核微生物（如真菌、藻类和原虫）和无细胞生物（如病毒）三类。

主要特性
微生物最大的特点，不但在於体积微小，而且在结构上亦相当简单。由於微生物体积极之微小，故相对面积较大，物质吸收快，转化快。微生物在生长与繁殖上亦是很迅速的，而且适应性强。从寒冷的冰川到极酷热的温泉，从极高的山顶到极深的海底，微生物都能够生存。

由於微生物适应性强，又容易在较短时间内积聚非常多的个体（例如10^10个/毫升的数量级），因此容易筛选并分离到突变株。容易得到微生物突变株的性质，给人类利用与开发微生物带来广阔契机，但也是导致抗药性的内在原因。

微生物的代谢
微生物的代谢指微生物（细胞）内发生的全部化学反应。 微生物的代谢异常旺盛，这是由於微生物的表面积与体积比很大（约是同等重量的成年人的30万倍），使它们能够迅速与外界环境进行物质交换。

代谢产物 微生物在代谢过程中，会产生多种代谢产物。根据代谢产物与微生物生长繁殖的关系，可以分为初级代谢产物和次级代谢产物两类。 初级代谢产物是指微生物通过代谢活动产生的、自身生长和繁殖所必须的物质，如氨基酸、核苷酸、多糖、脂质、维生素等。在不同种类的微生物细胞中，初级代谢产物的种类基本相同。 次级代谢产物是指微生物生长到一定阶段才产生的化学结构十分复杂，对该微生物无明显生理功能，或并非是微生物生长和繁殖所必须的物质，如抗生素、毒素、激素、色素等。不同种类的微生物所产生的次级代谢产物不相同，它们可能积累在细胞内，也可能排到外环境中。

代谢的调节 微生物在长期的进化过程中，形成了一整套完善的代谢调节系统，以保证证代谢活动经济而高效地进行。微生物的代谢调节主要有两种方式：酶合成的调节和酶活性的调节。 另外人工控制微生物代谢的措施包括改变微生物遗传特徵，控制生产过程中的各种条件等。

主要分类
微生物主要分为以下几类：（参见生物分类总表）

原核微生物
细菌(Bacteria)
古菌(Archaea)
真核微生物
真菌(Fungi)
原生生物(protozoan)
藻类(algae)
无细胞生物
病毒(virus)
类病毒(virusoid)
拟病毒(viroid)
朊毒体（亦称朊病毒、蛋白质质感染性颗粒）(prion)

微生物在自然界的存在
微生物在自然界中广泛存在，数目巨大。下表为一些生态环境中微生物细胞数目的估计：

密度 全球总数
海水 108~109 L-1 约1029
海洋沉积物 109 g-1 约3×1029
动物消化道 1011 g-1 约1025
地表或海底下深处 102~108 约1030

原核生物共构成全球生物量的25~50%。

微生物的作用
微生物与人类的生产、生活和生存息息相关。有很多食品（如酱油、醋、味精、酒、酸奶、奶酪、蘑菇）、工业品（如皮革、纺织、石化）、药品（如抗生素、疫苗、维生素、生态农药）是依赖于微生物制造的；微生物在矿产探测与开采、废物处理（如水净化、沼气发酵）等各种领域中也发挥重要作用。微生物是自然界唯一认知的固氮者（如大豆根瘤菌）与动植物残体降解者（如纤维素的降解），同时位于常见生物链的首末两端，从而完成碳、氮、硫、磷等生物质在大循环中的衔接。若没有微生物，众多生物就失去必需的营养来源、植物的纤维质残体就无法分解而无限堆积，就没有自然界当前的繁荣与秩序或人类的产生与维续。

此外，微生物对地球上气候的变化也起着重要作用。许多微生物直接参与了温室气体的排放或者吸收，而也有很多微生物可以成为未来的生物燃料[1]。

微生物与人类健康
微生物与人类健康密切相关。多数微生物对人体是无害的。实际上，人体的外表面（如皮肤）和内表面（如肠道）生活着很多正常、有益的菌群。它们占据这些表面并产生天然的抗生素，抑制有害菌的着落与生长；它们也协助吸收或亲自制造一些人体必需的营养物质，如维生素和氨基酸。这些菌群的失调（如抗生素滥用）可以导致感染发生或营养缺失。然而另一方面，人类与动植物的疾病也有很多是由微生物引起，这些微生物叫做病原微生物(pathogenic microorganism)或病原(pathogen)。重要的人类致病微生物列于下表中。

主要的人类致病微生物 疾病名称 致病原 全球感染（携带者）人数 每年新发病例数 每年死亡人数
结核 结核分枝杆菌 ~20亿人（全球三分之一人口） 881万例 (2003 [1]) 175万人 (2003 [2])
艾滋病 人类免疫缺陷病毒 4200万人 550万例 310万人
痢疾 志贺氏菌、痢疾杆菌、大肠埃希氏杆菌等 27亿例 190万人
疟疾 疟原虫 3-5亿例 100万人
乙型肝炎 乙型肝炎病毒 1000-3000万例 100万人
麻疹 麻疹病毒 3000万例 90万人
登革热 登革病毒 2000万例 2万4千人
流感 流感病毒 几乎全部人口 300-500万例 25万人
黄热病 黄热病毒 20万例 3万人

其他经常听说的致病微生物还有：流行已经完全得到控制或消灭的天花病毒（引起天花）和脊髓灰质炎病毒（导致小儿麻痹症）；引起炭疽病的炭疽杆菌；以及近年来显现的萨斯冠状病毒（引起严重急性呼吸道综合症，又名萨斯、也俗称非典型肺炎）和可能将在人类流行的禽流感。

对现代生物学研究与医学技术的贡献
现代生物学的若干基础性的重大发现与理论，是在研究微生物的过程中或以微生物为实验材料与工具取得的。这些理论包括：

证明DNA（脱氧核糖核酸）是遗传信息的载体（三大经典实验：肺炎球菌的转化实验、噬菌体实验、植物病毒的重组实验）
DNA的半保留复制方式（双螺旋的每一条子链分别、都是复制模板）
遗传密码子的解读（64个密码子各对应20种氨基酸及终止信号的哪一种）
基因的转录调节（operon, promoter, operator, repressor, activator的概念与调节方式）
信使RNA的翻译调节（terminator）
等等……（请添加）
现在，很多常用、通用的生物学研究技术依赖于微生物，比如：

分子克隆
重组蛋白在细菌或酵母中的表达
很多医学技术也依赖于微生物。比如：

以病毒为载体的基因治疗

⑺ 求一篇关于微生物驯化或相关的英文文献外加中文翻译，3000字以上

额。。。楼上的各位实在都太不靠谱了。。看来拿分的只能是我了。。。。跪谢楼上各位大大的不精彩答案啊

⑻ 求有关微生物的英文综述论文（review），译成中文5000字左右，急！！！

这种打工作量的 东西谁会帮你做 除非你出钱

⑼ 跪求一片SCI上发表的微生物方向英文版完整论文~~急用

1、Microbiological Implications of Periurban Agriculture and Water Reuse in Mexico City
Plos One 影响因子：4.351

网页地址：http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002305
pdf格式：http://www.plosone.org/article/fetchObjectAttachment.action;jsessionid=.ambra01?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0002305&representation=PDF

更多的呢可以到OA图书馆进行查询。 或者到哪里提问和问我。

⑽ 求微生物方面英文论文

推荐你去淘宝的：翰林书店，店主应该能下载到这类论文。我去下过，很及时的