微生物学英文教学课件：chapter1 The Main Themes of Microbiology

1、Microbiology(version 1.6)Part I Introduction to MicrobiologyHow to use your textbook?Whats the arrangement for the teaching?Why should we study microbiology IntroductionnLecture (64 hours)nLaboratory practice (32 hours)nHomework (about 30 times)nOpen-laboratory practiceArrangementWhy should we study

2、 microbiology? Two major reasonsmicrobiology deals with many important practical problems in medicine, agriculture, environment and industry. Biochemical and genetic study As a basic biological science As an applied biological science Provides research tools the experimental basis of microbiology th

3、e general principles of cell structure and function the classification and diversity of microorganisms biochemical processes in cells the genetic basis of microbial growth and evolution the ecological activities of microorganisms in nature the application of microorganisms in industry We will discus

4、s: How to use your textbook ?The OUTLINE provides an overview of the chapters main concepts.The INDEX has been designed to make text material more accessible.The CONCEPT and GLOSSARY provides definitions of important terms within each chapter.(Microbiology, Fifth Edition)Outstanding MICROGRAPHS are

5、included throughout. TABLES have been redesigned to make key information even more accessible to students.BOLDFACED TERMS are defined in the Glossary. BOXES provide additional, relevant information. Some take an historical perspective, some focus on techniques and applications, and others explore a

6、text topic in greater depth. QUESTIONS for Thought and Review challenge the students mastery of chapter concepts. Critical Thinking QUESTIONS allow students to test their analytical and problem-solving skills.Additional Reading provide useful tutorial and reference information.A very effective study

7、 technique to you SurveyQuestion ReadReviseRecord ReviewSQ4R TechniqueChapter OneThe Main Themes of MicrobiologyThe word microbe (microorganism) is used to describe an organism that is so small that, normally, it cannot be seen without the use of a microscope. Viruses, bacteria, fungi, protozoa and

8、some algae are all included in this category. 1.1 What is a microbe? Our world is populated by invisible creatures too small to be seen with the unaided eye. These life forms, the microbes or microorganisms, may be seen only by magnifying their image with a microscope. Yet other members of these gro

9、ups, particularly some of the algae and fungi, are larger and quite visible. For example, bread molds and filamentous algae are studied by microbiologists, yet are visible to the naked eye. Two bacteria that are visible without a microscope,Thiomargarita and Epulopiscium, also have been discovered.

10、A chain of Thiomargarita namibiensis cells as viewed with the light microscope.Note the external mucous sheath and the internal sulfur globules. The difficulty in setting the boundaries of microbiology led Roger Stanier to suggest that the field be defined not only in terms of the size of its subjec

11、ts but also in terms of its techniques. A microbiologist usually first isolates a specific microorganism from a population and then cultures it. Thus microbiology employs techniquessuch as sterilization and the use of culture mediathat are necessary for successful isolation and growth of microorgani

12、sms. The development of microbiology as a science is described in the following sections. Microbial worldOrganisms (living)Infectious agents (non-living)Prokaryotes (unicellular)eukaryotesvirusesviroidsprionsEubacteriaArchaeaAlgae (unicellular or multicellularFungi (unicellular or multicellularProto

13、zoa (unicellular)Other multicellular organismsMicrobes impinge on all aspects of life, just a few of these are listed below:The environmentMedicineFoodBiotechnologyResearch1.2 The Importance of Microbiology1. The environment2. Medicine3. Food4. Biotechnology5. ResearchPress here to continue Microbes

14、 are responsible for the cycling of carbon, nitrogen and phosphors (geochemical cycles), all essential components of living organisms . They are found in association with plants in symbiotic relationships, maintain soil fertilizer and may also be used to clean up the environment of toxic compounds (

15、bio-remediation). Some microbes are devastating plant pathogens , which destroy important food crops, but others may act as biological control agents against these diseases.The disease-causing ability of some microbes such as smallpox. (Variola virus), cholera (Vibrio cholera bacteria) and malaria (

16、Plasmodium protozoa) is well known. However, microorganisms have also provided us with the means of their control in the form of antibiotics and other medically important drugs.Microbes have been used for thousands of years, in many processes, to produce food, from brewing and wine making, through c

17、heese production and bread making, to the manufacture of soy sauce . At the other end of the scale, microbes are responsible for food spoilage, and disease-causing microbes are frequently carried on food.Traditionally microbes have been used to synthesize many important chemicals such as acetone and

18、 acetic acid . More recently the advent of genetic engineering techniques has led to the cloning of pharmaceutically important polypeptides into microbes, which may be produced on a large scale.Microbes have been used extensively as model organisms for the investigation of biochemical and genetical

19、processes as they are much easier to work with than more complex animals and plants. Millions of copies of the same single cell can be produced in large numbers very quickly and at low cost to give plenty of homogeneous experimental material. An additional advantage is that most people have no ethic

20、al objections to experiments with these microorganisms.Propionibacterium shermanii Flavor & eye formation Swiss cheese family Lactobacillus bugaricusLactobacillus lactisLactobacillus helveticus Acid and flavor Bulgarian buttermilk, yoghurt, kefir, koumiss, Swiss, Emmental, and Italian cheeses La

21、ctobacillus acidophilus Acid acidophilus buttermilk Streptococcus thermophilus Acid Emmental, Cheddar, and Italian cheeses, and yogurt Streptococcus diacetilactis Acid Sour cream, ripe cream, butter, cheese, buttermilk and starter cultures. Streptococcus lactisStreptococcus cremoris Acid Cultured bu

22、ttermilk, sour cream, cottage cheese, all types of foreign and domestic cheeses, and starter cultures. Streptococcus duransStreptococcus faecalis Acid and flavor Soft Italian, cheddar, and some Swiss cheeses. Leuconostoc citrovorumLeuconostoc dextranicum MicroorganismsMilk productsYeastFood Of cours

23、e microorganisms also have harmed humans and disrupted society over the millennia. e.g:In 1347 plague or black death struck Europe with brutal force. The plague had killed 1/3 of the population (about 25 million people). Today the struggle by us against killers like AIDS and malaria continues. The d

24、iscovery of microorganismsThe spontaneous generation conflictThe recognition of microbial role in diseaseThe discovery of microbial effects on organic and inorganic matterThe development of microbiology in this century1.3 The history of microbiology Even before microorganisms were seen, some investi

25、gators suspected their existence and responsibility for disease. Among others, the Roman philosopher Lucretius (about 9855 B.C.) and the physician Girolamo Fracastoro (14781553) suggested that disease was caused by invisible living creatures. The discovery of microorganisms The first person to accur

26、ately observe and describe microorganismsAntony van Leeuwenhock (1632-1723)The first person to observe and describe microorganisms was the amateur microscopist Antony van leeuwenhoek of Delft, Holland.Leeuwenhoek made his simple, single-lens microscope which could amplify the object being viewed 50

27、300 times. Between 1673 1723, he wrote a series of letters to the Royal Society of London describing the microbes he observed from the samples of rainwater, and humam mouth.Leeuwenhoeks microscope: Leeuwenhoeks microscope: A brass replica of a Leeuwenhoek microscope and how it is held. Beginning in

28、1673 Leeuwenhoek sent detailed letters describing his discoveries to the Royal Society of London. It is clear from his descriptions that he sawboth bacteria and protozoa. Leeuwenhoeks drawings of bacteria from the human mouth.A and B:bacillus; C and D:the track of bacteria movement;E:coccus; F:long

29、bacillus;G:spirochete;H:a cluster of cocci. The Conflict over Spontaneous GenerationThe Conflict over Spontaneous Generation From earliest times, people had believed in spontaneous generationspontaneous generationthat living organisms could develop from nonliving matter. As people observed that meat

30、 left out in the open soon “produced” maggots, that mushrooms appeared on rotting wood, that rats and mice emerged from piles of litter, and other similar phenomena. Even the great Aristotle (384322 B.C.) thought some of the simpler invertebrates could arise by spontaneous generation. This view fina

31、lly was challenged by the Italian physician Francesco Redi (16261697), who carried out a series of experiments on decaying meat and its ability to produce maggots spontaneously. Georg Schroeder and Theodor Van Dusch followed up these studies. They did not treat the air with heat or chemicals but pas

32、sed it through cotton wool to filter out microscopic organisms. Again, no microbes grew in the infusions. Although all these experiments should have finally laid to rest the arguments for spontaneous generation, they did not. Louis Pasteur (18221895) settled the matter once and for all. Pasteur repe

33、ated the experiments using cotton filters to trap dust from air and observed tiny objects (probably spores) in the filters. He also observed that these same filters would initiate growth in previously sterile broths. To further clarify that air and dust were the source of microbes,he filled flasks w

34、ith broth and fashioned their openings into elongate, swan-neckshaped tubes. The flasks openings were freely open to the air but were curved so that gravity would cause any airborne dust particles to deposit in the lower part of the necks. He heated the flasks to sterilize the broth and then incubat

35、ed them. As long as the flask remained intact, the broth remained sterile, but if the neck was broken off so that dust fell directly down into the container, microbial growth immediately commenced.Pasteurs swan neck flasks used in his experiments on the spontaneous generation of microorganismsConclu

36、sion: Microorganisms are not spontaneously generated from inanimate matter, but are produced by other microorganismsnFinal refutation of spontaneous generation birth of microbiology as a sciencenDiscovery of the existence of anaerobic life fermentationnVaccinesnPasteurizationPasteurs contributions:L

37、ouis Pasteur working in his laboratoryLouis Pasteur (1822 1895)1. Pasteur (1857) demonstrated that lactic acid fermentation is due to the activity of microorganisms.2. Pasteur (1861) conflict over spontaneous generation birth of microbiology as a science3. Pasteur (1881) developed anthrax vaccine4.

38、PasteurizationRobert Koch in his laboratoryThe recognition of microbial role in diseaseRobert Koch (1843 1910)1.The microorganisms must be present in every case of the disease but absent from healthy organisms.2.The suspected microorganisms must be isolated and grown in a pure culture.3.The disease

39、must result when the isolated microorganisms is inoculated into a healthy host.4.The same microorganisms must be isolated again from the diseased host . Kochs postulates About 1875,Koch used this experimental system to show that anthrax was caused by a bacterium called Bacillus anthracis. So useful

40、were his postulates that the causative agents of 20 other diseases were discovered between 1875 and 1900, and even today, they are the standard for identifying pathogens. Numerous exciting technologies emerged from Kochs prolific and probing laboratory work. During this golden age of the 1880s, he r

41、ealized that study of the microbial world would require separating microbes from each other and growing them in culture. It is not an overstatement to say that he and his colleagues invented many useful techniques : inoculation,isolation, media, maintenance of pure cultures, and preparation of speci

42、mens for microscopic examination. During Kochs studies on bacterial diseases, it became necessary to isolate suspected bacterial pathogens. At first he cultured bacteria on the sterile surfaces of cut, boiled potatoes. This was unsatisfactory because bacteria would not always grow well on potatoes.

43、He then tried to solidify regular liquid media by adding gelatin. Separate bacterial colonies developed after the surface had been streaked with a bacterial sample. The sample could also be mixed with liquefied gelatin medium. When the gelatin medium hardened, individual bacteria produced separate c

44、olonies. Despite its advantages gelatin was not an ideal solidifying agent because it was digested by many bacteria and melted when the temperature rose above 28C. A better alternative was provided by Fannie, one of Kochs assistants. She suggested the use of agar as a solidifying agentshe had been u

45、sing it successfully to make jellies for some time. Agar was not attacked by most bacteria and did not melt until reaching a temperature of 100C. One of Kochs assistants,Richard Petri, developed the petri dish (plate), a container for solid culture media. These developments made possible the isolati

46、on of pure cultures that contained only one type of bacterium, and directly stimulated progress in all areas of bacteriology. Koch also developed media suitable for growing bacteria isolated from the body. Because of their similarity to body fluids,meat extracts and protein digests were used as nutr

47、ient sources.The result was the development of nutrient broth and nutrient agar, media that are still in wide use today. By 1882 Koch had used these techniques to isolate the bacillus that caused tuberculosis.The Golden age of microbiology Koch and pure cultures Fermentation and Pasteurization Germ

48、theory of disease VaccinationBeijerinck made fundamental contributions to microbial ecology. He isolated Azotobacter and Rhizobium.The discovery of microbial effects on organic and inorganic matterThe Russian microbiologist Winograsky discovered that soil bacteria could oxidize iron, sulfur and ammo

49、nia to obtain energy, and also isolated nitrogen fixing bacteria.Sir Alexander Fleming discovered the antibiotic penicillin. He had the insight to recognize the significance of the inhibition of bacterial growth in the vicinity of a fungal contaminant when most other scientists probably would have s

50、imply discarded the contaminated plates.Alexander Fleming (1881-1955)1.4 Some Important Events in the Development of MicrobiologyDateMicrobiological Microbiological HistoryHistoryDate Microbiological Microbiological HistoryHistory1676Leeuwenhoek discovers “animalcules”1838-39Schwann,the Cell Theory1

51、857Pasteur shows that lactic acid fermentation is due to a microorganism1861Pasteur shows that microorganisms do not arise by spontaneous generation187677Koch demonstrates that anthrax is caused byBacillus anthracis1881 Koch cultures bacteria on gelatin; Pasteur develops anthrax vaccine1882Koch disc

52、overs tubercle bacillus, Mycobacterium tuberculosis1884Kochs postulates first published;Gram stain developed1928Griffith discovers bacterial transformation1929Fleming discovers penicillin1941Beadle and Tatum, one-gene-one-enzyme hypothesis1944Avery shows that DNA carries information during transform

53、ation;Waksman discovers streptomycin1953Watson and Crick propose the double helix structure for DNA1961Jacob and Monod propose the operon model of gene regulation1961-66Nirenberg, Khorana, and others elucidate the genetic code1973Cohen, Boyer use plasmid vectors to clone genes in bacteria1975Kohler

54、and Milstein develop technique for the production of monoclonal antibodies1977Recognition of archaea as a distinct microbial group by Woese and Fox;Gilbert and Sanger develop techniques for DNA sequencing1979Insulin synthesized using recombinant DNA techniques1983-84The polymerase chain reaction dev

55、eloped by Mullis1983-84The human immunodeficiency virus isolated and identified by Gallo and Montagnier1990First human gene-therapy testing begun1995Haemophilus influenzae genome sequenced1996 Yeast genome sequenced1997 Escherichia coli genome sequenced2000Discovery that Vibrio cholerae has two sepa

56、rate chromosomes Thus modern microbiology is a large discipline with many different specialties; it has a great impact on fields such as medicine, agricultural and food sciences, ecology, genetics, biochemistry, and molecular biology. For example, microbiology has been a major contributor to the ris

57、e of molecular biology. 1.5 The Scope and Relevance of Microbiology Microbiology is one of the largest and most complex of the biological sciences because it deals with many diverse biological disciplines. In addition to studying the natural history of microbes, it also deals with every aspect of mi

58、crobe-human and microbe environmental interactions. These interactions include genetics, metabolism, infection, disease, drug therapy, immunology, genetic engineering, industry, agriculture, and ecology. The subordinate branches that come under the large and expanding umbrella of microbiology are pr

59、esented in table 1.1.MicrobiologyBacteriologyProtozoologyParasitologyMicrobial MorphologyMycologyVirologyPhycology or AlgologyMicrobial physiologyMicrobial taxonomyMicrobial geneticsMolecular biologyMicrobial ecologyBranches of MicrobiologyBe classified on taxonomyBe classified on ecosystemBe classi

60、fied on applicationBe classified on basic biologyVirologyBacteriologyPhycologyMycologyProtozoologyAquatic microbiologySoil MicrobiologyMarine MicrobiologyPetroleum MicrobiologyIndustrial microbiologyMedical microbiologyAgricultural microbiologyFood microbiologyImmunologyGeneral microbiologyMicrobial tax