微生物學(xué)英語教學(xué)講義

1、1 / 29Introduction to Microbiology1. What is the unique features of Microorganisms?1.1 Small size, Simple structureAntoni Van Leeuwenhock: The word microorganism is used to describe an organism that is so smallthat, normally, it can not be seen without use of microscopy.The living organisms of micro

2、scopic sizeMost microorganisms are unicellularSome of them are non-cellular structure1.2 High diversityspecies. Bacteria ( actinomyce, algae, cyanobacteria)archaeafungi ( yeast, mold )protozoaviruse1.3 Widely distributed in various environment with large numbers soil. 109CFU/g water airplants, anima

3、ls, human bodyextreme environment, e.g. hot springs1.4 Fast growing, easy cultivation generation time, min.- hr.1.5 Easy mutation2. The place of microorganisms in the living world2.1 whittakers five kingdom concept (1969)Kingdom plantaeKingdom animaliaKingdom fungiKingdom protistaKingdom moneraThis

4、classification system was based on nutrition, photosynthesis, absorption and ingestion.2.2 Woeses three domains ( kingdoms)Domain bacteriaDomain ArchaeaDomain eucarya3. The scope of microbiologyMicrobiology is the study of living organisms of microscopic size, which include bacteria, fungi, algae,pr

5、otozoa and viruses. It is concerned with their morphology, reproduction, physiology, metabolism,genetics and classification. It includes the study of their distribution and function in nature, theirrelationship to each other and to other living organisms, their effects on human beings, animals andpl

6、ants.4. Why do we study microbiology?Microorganisms affect the well-being of people in a great many ways. They occur in large numbersin most natural environments. Some of them are beneficial and others are detrimental.4.1 The beneficial aspects? In Agriculture? Microbial fertilizer? Biological contr

7、ol? SCP? Microbial energy: methane gas for rural consumption? In food production? yogurt, cheese, wine(alcohol fermentation)? food ingredients2 / 29? In environment protection? treatment of waste materials? to decompose materials: pesticides, herbicides? In Biochemical industry? Antibiotics? enzymes

8、? Amino acides? organic acids? in medicine? Vaccine? Antibiotics penicillin? The potential applied areas of Microbiology? GMO Recombinant DNA technology? Microbial plastics? Microbial pesticides? Microbiosensor M傳感器? Microbial fuel cells微生物燃料電池? Microbial DNA chip微生物DNA芯片? Exploitation of microorgan

9、isms in extreme environments4.2 The detrimental aspects? Cause diseases: human beings animals Plants? spoil food? deteriorate materials: iron pipes, wood, clothObjectives:make full use and exploitation of the beneficial aspects; avoid and control the detrimentalaspects3 / 29Chapter 1 The Morphology

10、and Fi ne Structure of Microorga nisms1. Procaryotic Microorga ni sms1.1 Features disti nq uish ing procaryotic from Eucaryotic cellsfeatureProkaryotic cellsBacteria ( archaea)Eucaryotic cells(fu ngi, protozoa,pla nt, ani mal)Cell wallPeptidoglyca n as comp onentAbse nte of peptidoglyca nCell membra

11、 neGen erally do not containSterols prese nt; do not carry outsterol; contain part ofrespiratory and photos yn thesisrespiratory and, in some,photos yn theticmach ineryin vagi nati onnonCytoplasmic structuresMesosomePrese ntabsentRibosome70S80SMitoch on driaAbse ntprese ntChloroplastAbse ntprese ntG

12、olgi structureAbse ntprese ntEn doplosmic reticulumAbse ntprese ntnu cleusNot boun ded by nu clearBoun ded by nu clear membra ne;membra ne; one circularMore tha n one chromosomechromosome,Chromosome does notChromosomes have hist on es;Contain hist on es; no mitoticMitotic nu clear divisio ndivirsio

13、nNucleolus abse ntNucleolus prese nt1.2 Bacteria1.2.1 The size, shape and arran geme nt of bacterial cell? sphiericalcocci, coccus um; diameterA: diplococciB: streptococciC: tetradsD: staphylococciE: Sarcinae? straight rods: widnth x Length um, bacilli , bacillus, Lactobacillus? helically curved rod

14、s: spirilla , spirillumwidth x Len gth um (No. of curve)? filament: hyphae, hypha mycelium diameter of hypha(imActinoinyces: streptomyces speciessome are not con sta nt, but pleomorphic shape1.2.2 Simple stai ning tech niqueThe coloration of bacterial cell by applying a single solution of stain to a

15、 fixed smear is termedsimple stai ning.Steps:? Smear bacterial cells on a slide? dry and fix? The fixed smear is flooded with a dye solution for a specified period of time4 / 29? Wash off with H2O and dry the clide? exame the size. Shape and arrangement of bacterial cells under microscope1.2.3 The s

16、tructures and functions of bacterial cells1.2.3.1 Structures external to the cell wallA. Flagella, FlagellumBacterial flagella are hairlike, helical appendages that protrude through the cell wall and areresponsible for swimming motility.? chemical composition: protein subunits: flagellinLocation: po

17、lar: at one or both ends of the bacteriumLateral: alone the sides of the bacterium? function: swimming motility? gliding motility:some bacteria are motile when they are in contact with a solid surface. As they glide they exhibita sinuous, flexing motion. This kind of movement is comparatively slow,

18、only a few um per second.? Bacterial chemotaxismany, perhaps most, bacteria are capable of directed swimming toward or away from variouschemical compoundsa phemomenon called bacterial chemotaxis? Bacterial phototaxisphototrophic bacteria move towards increasing light intensities.? Pili, pilus( fimbr

19、iae)Pili are nonhelical, filamentous appendages that are thinner, shorter, and more numerous thanflagella. The well known is the F pilus ( or sex pilus), it serves as the port of entry of genetic materialduring bacterial mating.B. Capsules? Some bacterial cells are surrounded by a viscous substance

20、forming a covering layer or envelopearound the cell wall. If this layer can be visualized by light microscopy using special staining method, it ittermed a capsule . If it is too thin to be seen by light microscopy, it is termed microcapsule. If is soabundant that many cells are embedded in a common

21、matrix, the material is called slime .The conditions that some bacteria produce capsule ? High carbon content in media, low nitrogenThe chemical composition of capsule ? polysaccharides? polypeptides? The functions of capsule? They may provide protection against temporary drying by binding water mol

22、ecules? They may block attachment of bacterophages? They may promote attachment of bacteria to surfaces, e.g. Streptococcus mutans, a bacteriumassociated with producing dental caries, firmly adheres to the smooth surfaces of teeth because of itssecretion of a water-insoluble capsular polysaccharide.

23、C. spore and cyst? defination: under the undesirable growth conditions,e.g. Lack of nutrients, too acid, temperiture istoo high, Some species of bacteria produce thick-walled structure which is metabolically dormant andcan undergo germination and outgrowth to form a vegetative cell. This special str

24、ucture is termed sporewhich is either within the cell ( endospore ) or external to the cell (exospore).? shapes:? function: spores are extremely resistant to desiccation, staining, disinfecting chemicals, radiation, andheat. Some of sproes can resist boiling for several hours, most of spores can res

25、ist heat treatment at 80Cfor at least 10 minutes. Dormant structure.? Cyst: cyst resembles endospore, especially desiccation-resistant. But it does not resist to heattreatment. Genus Azotobacter cyst1.2.3.2 The cell wall? defination: A very rigid layer external to the cytoplasmic membrane. The main

26、function is to giveshape to the cell and prevent the cell from expanding and eventually bursting because of uptake of water.? peptidoglycan: an insoluble, porous, cross-linked polymer of enormous strength and rigidity.? Differential staining: staining procedures that make visible the differences bet

27、ween bacterial cells orparts of a bacterial cell are termed differential staining technique. The cells may be exposed to more than5 / 29one dye solution or staining reagent.? Gram staining: one of the most important and widely used differential staining techniques inmicrobiology is Gram staining . T

28、his technique was introduced by Christian Gram in 1884. In this processthe fixed bacterial smear is subjected to the following reagents in the order listed: crystal violet, iodinesolution, 95% alcohol (decolorizing agent), and safranin or some other suitable counterstain. Bacteriastained by the gram

29、 method fall into two groups:Gram positive bacteria(G+), which retain the crystal violet and hence appear deep violet in color; and Gram negative bacteria(G-), which lose the crystal violet, are counterstained by safranin, and hence appear red in color.? Why does this proceduce stain some bacteria p

30、urple-violet and others red?The wall of Gram positive bacteriathe structure and chamical compositionThe wall of Gram negative bacteriaThe structure and chemical composition1.2.3.3 The cytoplasmic MembraneImmediately beneath the cell wall is the cytoplasmic membrane. This structure is approximately7.

31、5nm thick and is composed mainly of phospholipids (2030%) and proteins (6070%).Mesosomemany bacteria, especially G+bacteria, possess membrane invaginations in the form of convolutedand vesicals termed mesosome.Functions of mesosome: DNA replicationcell divisionexport of exocellular enzymeThe functio

32、ns of cytoplasmic membranethe CM is a barrier to penetration by most molecules;specific proteins in the memtrane allow and facilitate the passage of small molecules (e.g. nutrients,waste products);The CM contains various enzymes involved in respiratory metabolism and phtosynthesis.CM is the site of

33、ATP generation, synthesis of capsular and cell wall components.1.2.3.4 The cytoplasmRibosomeIn the cytoplasmic area, granular in appearance and rich in the macromolecular RNA-proteinbodies known as Ribosomes, on which proteins are synthesized. In the prokaryotic cells, thesedimentation coefficient o

34、f ribosome is 70S.PHB: poly 3hydroxybutyrate1.2.3.5 The genetic materials6 / 29The nu cleusnot boun ded by n uclear membra neone circular chromosomechromosome does not contain hist onesnu cleolus abse ntPlasmidIn additi on to the no rmal DNA chromosome, extrachromosomal gen etic eleme nts are offen

35、foundin bacteria. These elements are called plasmids, and are capable of autonomous replication in thecytoplasm in the bacterial cell. Plasmids are circular pieces of DNA that are extra gen es.1.2.2 Bacterial Reproduct ion and colony1.2.2.1 Reproductio nTran sverse Binary Fissi onThe most com mon mode of bacterial cell divisio n in the usual growth cycle of bacterialpopulations is transverse binary fission, in which a single cell divides into two cells after develop ing a transverse septum. Tran sverse binary fissi on is an asexua