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1、Microorganisms and Microbiology,Chapter 1,Chapter outline,1.1 What is a microbe?1.2 The importance of Microbiology1.3 Microbes in our lives1.4 The history of microbiology1.5 Important events in the development of microbiology,Concepts,Microorganisms are responsible for many of the changes observed i
2、n organic and inorganic matter (e.g., fermentation and the carbon, nitrogen and sulfur cycles that occurred in nature.The development of microbiology as a scientific discipline has depended on the availability of the microscope and the ability to isolate and grow pure cultures of microorganisms.Micr
3、obiology is a large discipline, which has a great impact on other areas of biology and general human welfare,The word microbe (microorganism) is used to describe an organism that is so small that can not be seen without the use of a microscope. Viruses, bacteria, fungi, protozoa and some algae are a
4、ll 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.,Microbial world,Organisms (living),Infectious
5、agents (non-living),Prokaryotes (unicellular),eukaryotes,viruses,viroids,prions,Eubacteria,Archaea,Algae (unicellular or multicellular),Fungi (unicellular or multicellular),Protozoa (unicellular),Other (multicellular organisms),Most of the bacteria, protozoa, and fungi are single-celled microorganis
6、ms, and even the multicelled microbes do not have a great range of cell types. Viruses are not even cells, just genetic material surrounded by a protein coat and incapable of independent existence.,The size and cell type of microbes,The size and cell type of microbes,Microbes impinge on all aspects
7、of life, just a few of these are listed below:,The environment,Medicine,Food,Biotechnology,Research,1.2 The importance of microbiology,The environmentMedicineFoodBiotechnologyResearch,Press here to continue,Microbes are responsible for the geochemical cycles. They are found in association with plant
8、s in symbiotic relationships. Some microbes are devastating plant pathogens, but others may act as biological control agents against diseases.,The disease-causing ability of some microbes is well known. However, microorganisms have also provided us with the means of their control in the form of anti
9、biotics and other medically important drugs.,Microbes have been used to produce food, from brewing and wine making, through cheese production and bread making, to the manufacture of soy sauce. But microbes are also responsible for food spoilage.,Traditionally microbes have been used to synthesize im
10、portant chemicals. The advent of genetic engineering techniques has led to the cloning of polypeptides into microbes.,Microbes have been used as model organisms for the investigation of biochemical and genetical processes. Millions of copies of the same single cell can be produced very quickly and g
11、ive plenty of homogeneous experimental material. Most people have no ethical objections to experiments with these microorganisms.,1.3 Microbes in our lives,Microorganisms as Disease Agents Microorganisms and Agriculture Microorganisms and the Food Industry Microorganisms, Energy, and the Environment
12、 Microorganisms and the Future,Branches of Microbiology,Bacteriology,Protozoology,Parasitology,Microbial Morphology,Mycology,Virology,Phycology or Algology,Microbial physiology,Microbial taxonomy,Microbial genetics,Molecular biology,Microbial ecology,The future of microbiology is bright,Microbiology
13、 is one of the most rewarding of professions, because it gives its practitioners the opportunity to be in contact with all the other natural science and thus to contribute in many different ways to the betterment of human life.,1.4 The history of microbiology,In the field of observation, chance favo
14、rs only prepared minds. - Louis Pasteur,The discovery of microorganisms,The spontaneous generation conflict,The recognition of microbial role in disease,The discovery of microbial effects on organic and inorganic matter,The development of microbiology in this century,The discovery of microorganisms,
15、The first person to accurately observe and describe microorganisms,Antony van Leeuwenhock (1632-1723),The first person to observe and describe microorganisms was the amateur microscopist Antony van leeuwenhoek of Delft, Holland.,Leeuwenhock made his simple, single-lens microscope which could amplify
16、 the object being viewed 50 300 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 drawings of bacteria from the human mouth.,A drawing of one of the microscopes showin
17、g the lens a; mounting pin b; and focusing screws c and d.,lens,Object being viewed,adjusting,screws,Pasteurs contributions:,Louis Pasteur working in his laboratory,Louis Pasteur (1822 1895),Pasteur (1857) demonstrated that lactic acid fermentation is due to the activity of micro-organisms Pasteur (
18、1861) conflict over spontaneous generation birth of microbiology as a science Pasteur (1881) developed anthrax vaccine Pasteurization,Spontaneous generation that living organisms could develop from nonliving or decomposing matter.,The spontaneous generation conflict,Pasteurs swan neck flasks used in
19、 his experiments on the spontaneous generation of microorganisms,Conclusion:Microorganisms are not spontaneously generated from inanimate matter, but are produced by other microorganisms,Robert Koch in his laboratory,The recognition of microbial role in disease,Robert Koch (1843 1910),Kochs demonstr
20、ation of special organisms cause special diseases,Kochs postulates,The microorganisms must be present in every case of the disease but absent from healthy organisms.,The suspected microorganisms must be isolated and grown in a pure culture.,The disease must result when the isolated microorganisms is
21、 inoculated into a healthy host.,The same microorganisms must be isolated again from the diseased host,The Golden age of microbiology,Koch and pure cultures,Fermentation and Pasteurization,Germ theory of disease,Vaccination,The discovery of microbial effects on organic and inorganic matter,The Russi
22、an microbiologist Winograsky discovered that soil bacteria could oxidize iron, sulfur and ammonia to obtain energy, and also isolated nitrogenfixing bacteria. Beijerinck made fundamental contributions to microbial ecology. He isolated Azotobacter and Rhizobium.,Alexander Fleming (1881-1955),Sir Alex
23、ander 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.,Date Microbiological History1676 Leeuwenhoek discovers animalcules Pasteur shows that lactic acid fermentation is due to
24、 a microorganism Pasteur shows that microorganisms do not arise by spontaneous generation1867 Lister publishes his work on antiseptic surgery1869 Miescher discovers nucleic acids1876-1877 Koch demonstrates that anthrax is caused by Bacillus anthracis Laveran discovers Plasmodium, the cause of malari
25、a1881 Koch cultures bacteria on gelatin Pasteur develops anthrax vaccine,1.5 Important events in the development of microbiology,1884 Kochs postulates first published Metchnikoff describes phagocytosis Gram stain developed1887 Petri dish (plate) developed by Richard Petri Beijerinck isolates root no
26、dule bacteria Beijerinck proves that a virus particle causes the tobacco mosaic disease1921 Fleming discovers lysozyme1923 First edition of Bergeys Manual1928 Griffith discovers bacterial transformation1929 Fleming discovers penicillin Ruska develops first transmission electron microscope1935 Stanle
27、y crystallizes the tobacco mosaic virus,Avery shows that DNA carries information during transformation Waksman discovers streptomycin Watson and Crick propose the double helix structure for DNA1961-1966 Cohen et al use plasmid vectors to clone genes in bacteria1980 Development of the scanning tunnel
28、ing microscope1983-1984 The polymerase chain reaction developed by Mullis1990 First human gene-therapy testing begun Discovery of Thiomargarita namibiensis, the largest known bacterium Escherichia coli genome sequenced Discovery that Vibrio cholerae has two separate chromosomes,1.How did Pasteurs fa
29、mous experiment defeat the theory of spontaneous generation? 2.How can Kochs postulates prove cause and effect in a disease? 3.Who was the first person to use solid culture media in microbiology? What advantages do solid media offer for the culture of microorganisms?,REVIEW QUESTIONS:,4.What is the
30、enrichment culture technique and why was it a useful new method in microbiology? 5.When and how Alexander Fleming discovered antibiotics?,1. Pasteurs experiments on spontaneous generation were of enormous importance for the advance of microbiology, having an impact on the methodology of microbiology
31、, ideas on (he origin of life, and the preservation of food,to name just a few. Explain briefly how the impact of his experiments was felt on each of the topics listed.,APPLICATION QUESTIONS:,2. Describe the various lines of proof Robert Koch used to definitively associate the bacterium Mycobacteriu
32、m tuberculosis with the disease tuberculosis. How would his proof have been flawed if any of the tools he developed for studying bacterial diseases had not been available for his study of tuberculosis?,Ronald M.Atlas Clifford Renk Principles of Microbiology.,沈萍 1999. 微生物学 高等教育出版社。,J。尼克林著 林雅兰等译。 科学出版
33、社。,周德庆 2002. 微生物学教程 第二版。高等教育出版社。,李阜棣 胡正嘉 . 2000 微生物学。 第五版。中国农业出版社 。,赵斌 何绍江. 2002 微生物学实验。科学出版社。,Johnson.case. Laboratory Experiments in Microbiology.,John P.Harley Lansing M.Prescott Microbiology 3th Edition.,Lansing, M. Prescott ;John, P. Harley; and Donald, A. Klein . 2002. Microbiology, 5th ed. Mc
34、Graw-Hill .,Gerard J. Tortora ; Bardell R. Funke ; Christine L. 1998. Case. Microbiology An Introduction , 6th . Benjamin/Cummings.,Michael, T. Madigan; John, M. Martinko; and Jack, Parker. 2003. Brock Biology of Microorganisms , 10th . Prentice-Hall.,References:,Chapter 2 Cell Biology,2.1 Overview
35、of the structure of microbial cells 2.2 Procaryotic cell wall 2.3 Cytoplasmic membrane 2.4 Cellular genetic information 2.5 Cytoplasmic matrix Ribosome and Inclusions 2.6 Components external to the cell wall 2.7 Bacterial endospores 2.8 Comparison of the prokaryotic and eukaryotic cell,Chapter outli
36、ne,A procaryotic cell,A eucaryotic cell,Overview of cell structure,3. Their cell wall almost always contain the complex polysaccharide peptidoglycan,The prokaryotic cell,1. Their genetic material (DNA) is not enclosed within a membrane and they lack other membrane bounded organelles,2. Their DNA is
37、not associated with histidine,4. They are very small!,Size: Most bacteria fall within a range from 0.2 to 2.0 um in diameter and from 2 to 8 um in length,A rod-shaped prokaryote is typically about 1-5 micrometers (m) long and about 1 m wide,Microorganisms in general are very small and are completely
38、 invisible to the naked eye.,A cyanobacterium 8 x 50 um,size comparison of microorganisms,Visibility scale,Meters,Relative size of Microbes,Prokaryotes,Eukaryotes,Viruses,Naked eye,Light microscope,Electron microscope,a cell increases in size, its surface area to volume ratio decreases,Surface area
39、and volume relationships in cells,spirallum,Shape: Bacteria have a few basic shapes,spherical coccus,Rod-shaped bacillus,The cell wall of the bacterial cell is a complex, semi-rigid structure that is responsible for the characteristic shape of the cell. The cell wall surrounds the underlying, fragil
40、e plasma (cytoplasmic) membrane and protects it and internal parts of the cell from adverse changes in the surrounding environment.Almost all prokaryotes have cell walls.,Prokaryotic cell wall,Gram+,Gram-,Schematic diagram of bacterial cell walls,Bacteria can be divided into two major groups, called
41、 gram-positive and gram-negative. The original distinction between gram-positive and gram-negative was based on a special staining procedure, the Gram stain,The Gram-positive cell wall has a peptidoglycan layer that is relatively thick (ca. 40 nm) and comprises approximately 90% of the cell wall. Th
42、e cell walls of most Gram-positive eubacteria also have teichoic acids.,Gram-positive cell wall,Structure of the Repeating Unit in Peptidoglycan,These constituents are connected to form a repeating structure, the glycan tetrapeptide.,Peptidoglycan is composed of two sugar derivatives, N-acetylglucos
43、amine (NAG) and N-acetylmuramic acid (NAM), and a small group of amino acids consisting of L-alanine, D-alanine, D-glutamic acid, and either lysine or diaminopimelic acid (DAP).,Peptide and glycan units are connected in formation of the peptidoglycan sheet,Gram-positive Bacteria frequently have acid
44、ic polysaccharides called teichoic acids attached to their cell wall. The term teichoic acids includes all wall, membrane, or capsular polymers containing glycerophosphate or ribitol phosphate residues. These polyalcohols are connected by phosphate esters and usually have other sugars and D-alanine
45、attached.,Teichoic acids,Teichoic acids and lipoteichoic acids are arranged in the overall wall structure of gram-positive Bacteria .,Teichoic acid,Lipoteichoic acid,The Gram-negative cell wall is a thin layer attached to an outer membrane via lipoproteins. The outer membrane contains phospholipid o
46、n its inner surface and lipopolysaccharide (LPS) on its outer surface. The space between the outer membrane and the cytoplasmic membrane is called the periplasmic space.Teichoic acids do not occur in Gram-negative bacterial cell walls.,O side chain,Core polysaccharide,Lipid A,Chemical structure of L
47、ipopolysaccharide,Molecular model of E.coli lipopolysaccharide,The bonds between the carbohydrates in pseudopeptidoglycan are 1-3 instead of1-4 as in peptidoglycan.,CELL WALLS OF ARCHAEBACTERIA,The archaebacteria do not contain peptidoglycan in their cell walls as occurs in eubacteria.,N-acetylmuram
48、ic acid and D-amino acids are not found in the cell walls of archaebacteria.,( Differences from eubacteria ),Some archaebacteria have walls composed of pseudopeptidoglycan, which resembles the peptidoglycan of eubacteria but contains N-acetyltalosaminuronic acid instead of N-acetylmuramic acid and L
49、.-amino acids instead of the D-amino acids in eubacterial cell walls.,Protoplast Formation,Peptidoglycancan be destroyed by certain agents for instancelysozyme, that breaks the 1,4-glycosidic bonds between N-acetylglucosamine and N-acetylmuramic acid in the molecule.,The difference between gram-posi
50、tive and gram-negative bacteria is due to the physical nature of their cell walls. If the cell wall is removed from gram-positive bacteria, they become gram negative.,The peptidoglycan seems to act as a permeability barrier preventing loss of crystal violet. Gram-negative peptidoglycan is very thin,
