微生物英語作文

⑹ 誰能幫我找一篇與微生物有關的英文文章``````

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，因而需要藉助顯微鏡觀察的微小生物。微生物包括原核微生物（如細菌）、真核微生物（如真菌、藻類和原蟲）和無細胞生物（如病毒）三類。

主要特性
微生物最大的特點，不但在於體積微小，而且在結構上亦相當簡單。由於微生物體積極之微小，故相對面積較大，物質吸收快，轉化快。微生物在生長與繁殖上亦是很迅速的，而且適應性強。從寒冷的冰川到極酷熱的溫泉，從極高的山頂到極深的海底，微生物都能夠生存。

由於微生物適應性強，又容易在較短時間內積聚非常多的個體（例如10^10個/毫升的數量級），因此容易篩選並分離到突變株。容易得到微生物突變株的性質，給人類利用與開發微生物帶來廣闊契機，但也是導致抗葯性的內在原因。

微生物的代謝
微生物的代謝指微生物（細胞）內發生的全部化學反應。 微生物的代謝異常旺盛，這是由於微生物的表面積與體積比很大（約是同等重量的成年人的30萬倍），使它們能夠迅速與外界環境進行物質交換。

代謝產物 微生物在代謝過程中，會產生多種代謝產物。根據代謝產物與微生物生長繁殖的關系，可以分為初級代謝產物和次級代謝產物兩類。 初級代謝產物是指微生物通過代謝活動產生的、自身生長和繁殖所必須的物質，如氨基酸、核苷酸、多糖、脂質、維生素等。在不同種類的微生物細胞中，初級代謝產物的種類基本相同。 次級代謝產物是指微生物生長到一定階段才產生的化學結構十分復雜，對該微生物無明顯生理功能，或並非是微生物生長和繁殖所必須的物質，如抗生素、毒素、激素、色素等。不同種類的微生物所產生的次級代謝產物不相同，它們可能積累在細胞內，也可能排到外環境中。

代謝的調節 微生物在長期的進化過程中，形成了一整套完善的代謝調節系統，以保證證代謝活動經濟而高效地進行。微生物的代謝調節主要有兩種方式：酶合成的調節和酶活性的調節。 另外人工控制微生物代謝的措施包括改變微生物遺傳特徵，控制生產過程中的各種條件等。

主要分類
微生物主要分為以下幾類：（參見生物分類總表）

原核微生物
細菌(Bacteria)
古菌(Archaea)
真核微生物
真菌(Fungi)
原生生物(protozoan)
藻類(algae)
無細胞生物
病毒(virus)
類病毒(virusoid)
擬病毒(viroid)
朊毒體（亦稱朊病毒、蛋白質質感染性顆粒）(prion)

微生物在自然界的存在
微生物在自然界中廣泛存在，數目巨大。下表為一些生態環境中微生物細胞數目的估計：

密度 全球總數
海水 108~109 L-1 約1029
海洋沉積物 109 g-1 約3×1029
動物消化道 1011 g-1 約1025
地表或海底下深處 102~108 約1030

原核生物共構成全球生物量的25~50%。

微生物的作用
微生物與人類的生產、生活和生存息息相關。有很多食品（如醬油、醋、味精、酒、酸奶、乳酪、蘑菇）、工業品（如皮革、紡織、石化）、葯品（如抗生素、疫苗、維生素、生態農葯）是依賴於微生物製造的；微生物在礦產探測與開采、廢物處理（如水凈化、沼氣發酵）等各種領域中也發揮重要作用。微生物是自然界唯一認知的固氮者（如大豆根瘤菌）與動植物殘體降解者（如纖維素的降解），同時位於常見生物鏈的首末兩端，從而完成碳、氮、硫、磷等生物質在大循環中的銜接。若沒有微生物，眾多生物就失去必需的營養來源、植物的纖維質殘體就無法分解而無限堆積，就沒有自然界當前的繁榮與秩序或人類的產生與維續。

此外，微生物對地球上氣候的變化也起著重要作用。許多微生物直接參與了溫室氣體的排放或者吸收，而也有很多微生物可以成為未來的生物燃料[1]。

微生物與人類健康
微生物與人類健康密切相關。多數微生物對人體是無害的。實際上，人體的外表面（如皮膚）和內表面（如腸道）生活著很多正常、有益的菌群。它們占據這些表面並產生天然的抗生素，抑制有害菌的著落與生長；它們也協助吸收或親自製造一些人體必需的營養物質，如維生素和氨基酸。這些菌群的失調（如抗生素濫用）可以導致感染發生或營養缺失。然而另一方面，人類與動植物的疾病也有很多是由微生物引起，這些微生物叫做病原微生物(pathogenic microorganism)或病原(pathogen)。重要的人類致病微生物列於下表中。

主要的人類致病微生物 疾病名稱 致病原 全球感染（攜帶者）人數 每年新發病例數 每年死亡人數
結核 結核分枝桿菌 ~20億人（全球三分之一人口） 881萬例 (2003 [1]) 175萬人 (2003 [2])
艾滋病 人類免疫缺陷病毒 4200萬人 550萬例 310萬人
痢疾 志賀氏菌、痢疾桿菌、大腸埃希氏桿菌等 27億例 190萬人
瘧疾 瘧原蟲 3-5億例 100萬人
乙型肝炎 乙型肝炎病毒 1000-3000萬例 100萬人
麻疹 麻疹病毒 3000萬例 90萬人
登革熱 登革病毒 2000萬例 2萬4千人
流感 流感病毒 幾乎全部人口 300-500萬例 25萬人
黃熱病 黃熱病毒 20萬例 3萬人

其他經常聽說的致病微生物還有：流行已經完全得到控制或消滅的天花病毒（引起天花）和脊髓灰質炎病毒（導致小兒麻痹症）；引起炭疽病的炭疽桿菌；以及近年來顯現的薩斯冠狀病毒（引起嚴重急性呼吸道綜合症，又名薩斯、也俗稱非典型肺炎）和可能將在人類流行的禽流感。

對現代生物學研究與醫學技術的貢獻
現代生物學的若干基礎性的重大發現與理論，是在研究微生物的過程中或以微生物為實驗材料與工具取得的。這些理論包括：

證明DNA（脫氧核糖核酸）是遺傳信息的載體（三大經典實驗：肺炎球菌的轉化實驗、噬菌體實驗、植物病毒的重組實驗）
DNA的半保留復制方式（雙螺旋的每一條子鏈分別、都是復制模板）
遺傳密碼子的解讀（64個密碼子各對應20種氨基酸及終止信號的哪一種）
基因的轉錄調節（operon, promoter, operator, repressor, activator的概念與調節方式）
信使RNA的翻譯調節（terminator）
等等……（請添加）
現在，很多常用、通用的生物學研究技術依賴於微生物，比如：

分子克隆
重組蛋白在細菌或酵母中的表達
很多醫學技術也依賴於微生物。比如：

以病毒為載體的基因治療

⑺ 求一篇關於微生物馴化或相關的英文文獻外加中文翻譯，3000字以上

額。。。樓上的各位實在都太不靠譜了。。看來拿分的只能是我了。。。。跪謝樓上各位大大的不精彩答案啊

⑻ 求有關微生物的英文綜述論文（review），譯成中文5000字左右，急！！！

這種打工作量的 東西誰會幫你做 除非你出錢

⑼ 跪求一片SCI上發表的微生物方向英文版完整論文~~急用

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

網頁地址：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圖書館進行查詢。 或者到哪裡提問和問我。

⑽ 求微生物方面英文論文

推薦你去淘寶的：翰林書店，店主應該能下載到這類論文。我去下過，很及時的