Lecture 1 Microorganisms & Microbiology

Transcription

1 Lecture 1 Microorganisms & Microbiology Chapter 1 in BROCK BIOLOGY OF MICROORGANISMS Zhao Liping and Chen Feng School of Life Science and Technology Shanghai Jiao Tong University

2 1.1 Microbiology As a basic biological science, microbiology provides tools for probing the processes of life. As an applied biological science, microbiology deals with many important practical problems in medicine, agriculture, and industry.

3 1.2 Microorganisms as Cells Characteristics of living systems Hallmarks / characteristics 1. Metabolism 代谢 2. Growth 生长 3. Differentiation 分化 4. Communication 交流 5. Movement 运动 6. Evolution 进化 heredity and mutation-information flow

4 1.2.2 Cells as chemical machines and as coding devices Cells are self-replicating entities 可自我复制的主体, they can be viewed in two ways: As chemical machines 作为化学机器的细胞 carrying out chemical transformations of non-living materials to living materials to provide energy and precursors for cell reproduction As coding devices 作为编码装置的细胞 serving as storehouses and processors of genetic information (DNA) to give the cell instructions to make new copies of itself

5 Cells are both machines and coding devices The link between these two cellular attributes is growth. Machine and coding functions work together to reproduce cells. 生长将这两项功能合二为一, 共同繁殖新细胞 Coordination and regulation are highly needed between these two functions. 需要协调 ( 与调节 )

6 The machine and coding functions of the cell

7 1.3 Microorganisms A large and diverse group of microscopic organisms that exist as single cells or cell clusters, it also include non-cellular life forms such as viruses and prions. 微生物 : 微小的细胞或非细胞生物

8 Compared with plant and animal cells, microorganisms are: Very small-bacteria 0.5-5μm, 微小 Highly diverse-all kinds of morphology, 形态多样 leading an independent living 独立生活

9 1.4 The Impact of Microorganisms on Humans 微生物对人类的影响 Disease agents 病原物 Human, animal, plants Agriculture 农业 Nitrogen fixation-root nodule 根瘤 Animal digestion-rumen 瘤胃 Food industry 食品工业 Spoilage Fermented food Energy 能源 Biomass Biofuels Environment 环境 Bioremediation 生物修复

10 Pathogens-harmful microorganisms Time: 1350 A.D. Place: the European continent. In less than two years' time, the Bubonic Plague wiped out half the population of Europe. Fleas bit rats and then bit man, but no one knew it. An estimated 25 million people died in 14 months. Some individual cities had a mortality as high as 90%. Bodies were piled into carts and dragged away to be burned in common graves. It was a most grotesque way to die: bleeding and screaming and having one's organs literally liquefy. From infection to death took perhaps one week 年黑死病流行于欧洲,2500 万人在 14 个月内死亡 Bubonic Plague 黑死病, 淋巴腺鼠疫

11 The leading causes of death in the 1900 was influenzae, pneumonia, tuberculosis, and gastroenteritis 流感 肺炎 肺结核 肠胃炎在 1900 年是主要的致死原因

12 In the 1990 s, infectious diseases only ranked 5th as a major cause of death. 上世纪 90 年代, 感染性疾病重要性降低, 在致死因素中排第五位.

13 II. Pathways of Discovery in Microbiology Technological developments have been closely related with birth and growth of microbiology. 技术发展对微生物学发展的重大意义 Microscopy Culture technique DNA manipulation technology

14 1.5 Historical Roots of Microbiology: Microscopy 显微技术 Fruiting bodies observed first with microscope by Robert Hook in 1664 Discovery of microorganisms (wee animalcules) by Antoni van Leeuwenhoek in rain-, sea- and snow-water (1677) 虎克与吕文虎克

15 A Modern Bright-Field Microscope

16 1.6 Pasteur, Koch and Pure Cultures Birth of Microbiology in the mid and late 1800s Does spontaneous generation occur? 自然发生说 What is the nature of contagious disease? 传染病的本质

17 Pasteur and the Downfall of Spontaneous Generation French chemist Louis Pasteur ( ), defeated the theory of spontaneous generation 巴斯德 Downfall of Spontaneous generation Theory of spontaneous generation Ancient Egypt- frog from mud Food spoilage- microbes could be directly transformed from non-living matters

18 Pasteur and the Downfall of Spontaneous Generation Downfall 1 st experiment of Spontaneous generation (1) Methods Collection of microbes from the air Guncotton filters to stop particles Guncotton filters dissolved in alcohol and ether Examined particles under microscope Results Microbial cells found in the air and those in spoiled food were not distinguishable Conclusion Organisms found in spoiled materials came from microorganisms in the air Criticism: Can not exclude the possibility of spontaneous generation

19 Pasteur and the Downfall of Spontaneous Generation 2 nd Downfall experiment of Spontaneous generation (2) Method Broth in sealed flask Heating Results Heated broth separated from the air never spoils Conclusion Spontaneous does not occur, microbial cells can only come from the air/ environment. Criticism: Fresh air is needed for spontaneous generation, heating destroyed the power for spontaneous generation in the air sealed in the flask.

20 Pasteur and the Downfoall of Spontaneous Generation Downfall of Spontaneous generation (3) 3 rd experiment Method Broth in flask with swan neck, fresh air could get inside but not particles from the air Heating the broth. Results Heated broth in the open flask did not spoil Conclusion Spontaneous does not occur, cells can only come from cells

21 Pasteur and the Downfoall of Spontaneous Generation Downfall of Spontaneous generation (3) 3 rd experiment Method Broth in flask with swan neck, fresh air could get inside but not particles from the air Heating the broth. Results Heated broth in the open flask did not spoil Contact with particles stopped in the neck led to quick spoilage Conclusion Spontaneous does not occur, cells can only come from cells Criticism: No criticism

22 sterilizing the contents of the flask. FLASH

23 if the flask remains upright, no microbial growth will occur

24 if microbes trapped in the neck reach the sterile liquid, growth will occur

25 Koch and the Germ Theory of Disease Robert Koch ( ), physician, developed the Germ theory of disease Koch s Work with anthrax 炭疽热 Koch s postulates 柯赫法则

26 Koch s Work with anthrax (1) Method Microscopic observation Results Bacterial cells were observed in the blood of animals with the disease Conclusion The disease might be caused by this bacterium Criticism: The bacterium might as well be a result of the disease

27 Koch s Work with anthrax (2) Method Transfer of disease with blood among animals Observe with microscope of the artificially infected animals Results Blood containing the bacterium could cause disease in healthy animals and newly infected animal s blood contained the bacterial cells Highly repeatable Conclusion The bacteria in the blood of infected animals can cause disease in healthy animals Criticism: How do you know it is the bacteria not something else resistant to microscopic observation in the blood caused the infection?

28 Koch s Work with anthrax (3) Method Culture of the bacterium in nutrient broth Transfer of disease by the isolated bacteria Microscopic observation Results Isolated bacteria caused disease in healthy animals The same bacteria were isolated from dead animals Conclusion The bacterial cells in the blood of infected animals are indeed the reason for the disease Germ theory of disease established

29 Koch s postulates 柯赫法则 On the basis of Germ Theory of Disease and other experiments, Koch formulated Koch s postulates for proving that a specific type of microorganism causes a specific disease. FLASH

30 Koch s postulates Postulate #1 the suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals.

31 Postulate #2 the suspected organism should be grown in pure culture.

32 Postulate #3 the cells from a pure culture of the suspected organism should cause disease in a healthy animal.

33 Postulate #4 the organism should be reisolated and shown to be the same as the original.

34 Koch s other contributions (1) Development of pure culture technique 纯培养技术 Potato slice Solid medium with gelatin(broth) 明胶培养基 Solid medium with agar 琼脂培养基

35 Koch s other contributions (2) Demonstration of causal agent of tuberculosis 肺结核 Koch s methods (developed by himself) 1. Microscopy 2. Differential staining 鉴别染色法 of bacteria and human tissues 3. Pure culture isolation of bacteria 4. Animal inoculation 动物接种 Received Nobel Prize for Physiology or Medicine in 1905

36 Differential staining of bacteria and human tissues 对人体组织和细菌的鉴别染色法 Cells of M. tuberculosis stain blue in a lung tissue sample Chen whereas Feng, Shanghai the tissue Jiao stains Tong brown. University

37 Cells of M. tuberculosis stain blue in a sputum sample from a TB patient TB 病人痰中的结核分枝杆菌

38 M. tuberculosis growing on a glass plate of coagulated blood serum inside a glass box 在玻璃盒中用凝固血清培养基培养结核分枝杆菌

39 A colony of M. tuberculosis appears as long "cordlike" forms when taken from a glass plate 结核杆菌的绳索状细菌菌落

40 Some landmarks in microbiology in the past. The icons or photos above the dates are symbolic of the discoveries; each has been covered here or will be revisited in later chapters.

41 Thank you for your listening!