1、Microorganisms and MicrobiologyChapter 1 Chapter outline1.1 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 microbiologyConceptsConceptsMicroorganisms are responsible for many of the changes observ
2、ed in 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.
3、Microbiology is a large discipline, which has a great impact on other areas of biology and general human welfareThe 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 ar
4、e 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. Microbial worldOrganisms (living)Infectious
5、agents (non-living)Prokaryotes (unicellular)eukaryotesvirusesviroidsprionsEubacteriaArchaeaAlgae (unicellular or multicellular)Fungi (unicellular or multicellular)Protozoa (unicellular)Other (multicellular organisms)Most of the bacteria, protozoa, and fungi are single-celled microorganisms, and even
6、 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 MicrobeApproximate range of sizes Cell type Viruses 0.01-0.25m Acellular Bacteri
7、a 0.1-10m Prokaryote Fungi 2m-1m Eukaryote Protozoa 2-1000m Eukaryote Algae 1m-several meters EukaryoteThe size and cell type of microbesMicrobes impinge on all aspects of life, just a few of these are listed below:The environmentMedicineFoodBiotechnologyResearch1.2 The importance of microbiology Th
8、e environment Medicine Food Biotechnology ResearchPress here to continue Microbes are responsible for the geochemical cycles. They are found in association with plants in symbiotic relationships. Some microbes are devastating plant pathogens, but others may act as biological control agents against d
9、iseases.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 antibiotics and other medically important drugs. Microbes have been used to produce food, from brewing and wine making, through cheese prod
10、uction and bread making, to the manufacture of soy sauce. But microbes are also responsible for food spoilage.Traditionally microbes have been used to synthesize important chemicals. The advent of genetic engineering techniques has led to the cloning of polypeptides into microbes.Microbes have been
11、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 give plenty of homogeneous experimental material. Most people have no ethical objections to experiments with these microorganisms.1.3 Micr
12、obes in our lives Microorganisms as Disease Agents Microorganisms and Agriculture Microorganisms and the Food Industry Microorganisms, Energy, and the Environment Microorganisms and the Future Branches of MicrobiologyBacteriologyProtozoologyParasitologyMicrobial MorphologyMycologyVirologyPhycology o
13、r AlgologyMicrobial physiologyMicrobial taxonomyMicrobial geneticsMolecular biologyMicrobial ecologyThe future of microbiology is brightThe future of microbiology is brightMicrobiology is one of the most rewarding of professions, because it gives its practitioners the opportunity to be in contact wi
14、th all the other natural science and thus to contribute in many different ways to the betterment of human life.1.4 The history of microbiologyIn the field of observation, chance favors only prepared minds. - Louis Pasteur The discovery of microorganismsThe spontaneous generation conflictThe recognit
15、ion of microbial role in diseaseThe discovery of microbial effects on organic and inorganic matterThe development of microbiology in this centuryThe discovery of microorganismsThe first person to accurately observe and describe microorganismsAntony van Leeuwenhock (1632-1723)The first person to obse
16、rve and describe microorganisms The first person to observe and describe microorganisms was the amateur microscopist Antony van leeuwenhoek was the amateur microscopist Antony van leeuwenhoek of Delft, Holland.of Delft, Holland.Leeuwenhock made his simple, single-lens microscope which could amplify
17、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 showing t
18、he lens a; mounting pin b; and focusing screws c and d.lensObject being viewedadjustingscrewsPasteurs contributions:Louis Pasteur working in his laboratoryLouis Pasteur (1822 1895) Pasteur (1857) demonstrated that lactic acid fermentation is due to the activity of micro-organisms Pasteur (1861) conf
19、lict over spontaneous generation birth of microbiology as a science Pasteur (1881) developed anthrax vaccine Pasteurization Spontaneous generationSpontaneous generation that living organisms could develop from nonliving or decomposing matter.The spontaneous generation conflictPasteurs swan neck flas
20、ks used in his experiments on the spontaneous generation of microorganismsConclusion:Microorganisms are not spontaneously generated from inanimate matter, but are produced by other microorganismsRobert Koch in his laboratoryThe recognition of microbial role in diseaseRobert Koch (1843 1910)Kochs dem
21、onstration 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 microorganis
22、ms is inoculated into a healthy host. The same microorganisms must be isolated again from the diseased hostThe Golden age of microbiology Koch and pure cultures Fermentation and Pasteurization Germ theory of disease VaccinationThe discovery of microbial effects on organic and inorganic matter The Ru
23、ssian 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 Ale
24、xander 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 animalcules1857 Pasteur shows that lactic acid fermentation is du
25、e to a microorganism1861 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 anthracis1880 Laveran discovers Plasmodium, the cau
26、se of malaria1881 Koch cultures bacteria on gelatin Pasteur develops anthrax vaccine1.5 Important events in the development of microbiology1884 Kochs postulates first published Metchnikoff describes phagocytosis Gram stain developed1887 Petri dish (plate) developed by Richard Petri1889 Beijerinck is
27、olates root nodule bacteria1899 Beijerinck proves that a virus particle causes the tobacco mosaic disease1921 Fleming discovers lysozyme1923 First edition of Bergeys Manual19 2 8 G r iffith discovers bacterial transformation1929 Fleming discovers penicillin1933 Ruska develops first transmission elec
28、tron microscope1935 Stanley crystallizes the tobacco mosaic virus1944 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 Deve
29、lopment of the scanning tunneling microscope1983-1984 The polymerase chain reaction developed by Mullis1990 First human gene-therapy testing begun1997 Discovery of Thiomargarita namibiensis, the largest known bacterium Escherichia coli genome sequenced2000 Discovery that Vibrio cholerae has two sepa
30、rate chromosomes 1.How did Pasteurs famous 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 microorgan
31、isms?REVIEW QUESTIONS: 4.What is the 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 impac
32、t on the methodology of microbiology, 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 a
33、ssociate the bacterium Mycobacterium 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.沈萍沈萍 19
34、99. 微生物学微生物学 高等教育出版社。高等教育出版社。J J。尼克林著。尼克林著 林雅兰等译。林雅兰等译。 科学出版社。科学出版社。周德庆周德庆 2002. 微生物学教程微生物学教程 第二版。高等教育出版社。第二版。高等教育出版社。李阜棣李阜棣 胡正嘉胡正嘉 . 2000 微生物学。微生物学。 第五版。中国农业出版社第五版。中国农业出版社 。赵斌赵斌 何绍江何绍江. 2002 微生物学实验。科学出版社。微生物学实验。科学出版社。Johnson.case. Laboratory Experiments in Microbiology.John P.Harley Lansing M.Presc
35、ott Microbiology 3th Edition.Lansing, M. Prescott ;John, P. Harley; and Donald, A. Klein . 2002. Microbiology, 5th ed. McGraw-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,
36、 Parker. 2003. Brock Biology of Microorganisms , 10th . Prentice-Hall. References:Chapter 2Chapter 2 Cell Biology 2.1 Overview 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 Co
37、mponents external to the cell wall 2.7 Bacterial endospores 2.8 Comparison of the prokaryotic and eukaryotic cellChapter outlineA procaryotic cellA eucaryotic cell Overview of cell structure3. Their cell wall almost always contain the complex polysaccharide peptidoglycanThe prokaryotic cell1. Their
38、genetic material (DNA) is not enclosed within a membrane and they lack other membrane bounded organelles2. Their DNA is not associated with histidine4. 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 lengthA rod-shaped prokaryote is ty
39、pically about 1-5 micrometers (m) long and about 1 m wideMicroorganisms in general are very small and are completely invisible to the naked eye. A cyanobacterium 8 x 50 umsize comparison of microorganismsVisibility scale Meters Relative size of MicrobesProkaryotesEukaryotesVirusesNaked eyeLight micr
40、oscopeElectron microscopea cell increases in size, its surface area to volume ratio decreasesSurface area and volume relationships in cellsspirallumShape: Bacteria have a few basic shapesspherical coccusRod-shaped bacillusThe cell wall of the bacterial cell is a complex, semi-rigid structure that is
41、 responsible for the characteristic shape of the cell. The cell wall surrounds the underlying, fragile 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 wallGram+Gra
42、m-Schematic diagram of bacterial cell wallsBacteria can be divided into two major groups, called 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
43、 layer that is relatively thick (ca. 40 nm) and comprises approximately 90% of the cell wall. The cell walls of most Gram-positive eubacteria also have teichoic acids.Gram-positive cell wallStructure of the Repeating Unit in PeptidoglycanThese constituents are connected to form a repeating structure
44、, the glycan tetrapeptide.Peptidoglycan is composed of two sugar derivatives, N-acetylglucosamine (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 c
45、onnected in formation of the peptidoglycan sheetGram-positive Bacteria frequently have acidic 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
46、polyalcohols are connected by phosphate esters and usually have other sugars and D-alanine attached. Teichoic acidsTeichoic acids and lipoteichoic acids are arranged in the overall wall structure of gram-positive Bacteria .Teichoic acidLipoteichoic acidThe Gram-negative cell wall is a thin layer att
47、ached to an outer membrane via lipoproteins. The outer membrane contains phospholipid on 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
48、 bacterial cell walls. O side chainCore polysaccharideLipid AChemical structure of LipopolysaccharideMolecular 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 n
49、ot contain peptidoglycan in their cell walls as occurs in eubacteria. N-acetylmuramic 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 eubacter
50、ia but contains N-acetyltalosaminuronic acid instead of N-acetylmuramic acid and L.-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-acetylgluco
