《微生物学》课件 Microbiology Chapter 7

1、Chapter 7Microbial TaxonomyThe number of recorded organisms:1,500,000; microorganisms :150,000 200,000Taxonomy The science of classification, identification and nomenclature of organismsPhylogeny of microorganismThe study of the evolutionary history of microorganisms7.1 Evolutionary chronometersCert

2、ain cellular macromolecules can serve as evolutionary chronometers-actual measures of evolutionary change7.1.1 Choosing the right evolutionary chronometers1. The molecule should be universally distributed across the group chosen for study.2. The molecule must be functionally homologous in each organ

3、ism3. The sequence of the molecule must be conserved4. The size of the molecule must be consideredRibosomal RNA (rRNA) 40S60S18S28S5.8S5S2300bp4200bp160bp120bp80S rRNA30S50S16S23S5S1500bp2900bp120bp70S rRNA生物核糖体RNA亚基组成The Three-Domain SystemThe Three-Domain System7.1.2 Taxonomic Hierarchy域 domain 门

4、phylum 纲 class 目 order 科 family 属 genus 种 species (1) Species DefinitionSpecies (sp.) In microbiology, a collection of strains which all share the same major properties but which differ in one or more significant properties from other collection of strains.Species DefinitionSpecies(sp.):Similar phen

5、otype, DNA homology 70% Tm5 Type strain :Bradyrhizobium japonicum ATCC 10324T。 Subspecies(ssp. subsp)Form生物型（biovar）化学型（chemovar）形态型（morphovar）致病型（pathovar）噬菌型（phagovar）血清型（serovar）7.1.3 International nomenclatureBacillus subtilis Chon 1872genus sp.Bacillus thuringiensis subsp. Galleriagenus sp. spp

6、.7.2 The methods of classification and identification(1) Traditional classificationMorphologyCulturePhysiologyBiochemistryEcology 从温血动物的肠道分离细菌获得纯培养物革兰氏反应革兰氏阴性革兰氏阳性杆状非杆状兼性专性好氧发酵乳糖，产酸产气不发酵乳糖生化试验：（阳性：吲哚，甲基红，粘质酸盐阴性：柠檬酸，VP，H2S）大肠杆菌(2) Numerical Taxonomy(3) Molecular taxonomyG+C mol%DNA热变性曲线（参照现代微生物学，刘志恒主

7、编，2002） 70 80 Tm 90 1001.5 14131.21.11.0解链温度T 260nm光吸收值DNA-DNA hybridization16S rRNA sequence微生物纯培养物提取DNA获得总DNA，作为PCR扩增模板加热分开两条链加入特殊引物用DNA聚合酶进行引物的延伸+重复上述步骤进行多个PCR循环，以产生多个拷贝的16S rDNA用Sanger法测序电泳检查扩增产物应用计算机程序进行序列分析构建系统发育树DNA fingerprints -RAPDAFLP具体操作流程基因组DNATATAATGATCAATTGCATTATru1IEcoRIATGAAATCTTCGT

8、AACTATGAATTCGTTAAGCATTru1I接头CAATTGEcoRI接头酶切连接扩增CATGATATru1I引物CCAATTCGTEcoRI引物GCTATACGTAACTATGAATTCGTTAAGTCCAG53AFLP作用原理AFLP标记的聚丙烯酰胺电泳图谱AFLP 指纹图谱的UPGMA 相似性分析树状图Polyphasic taxonomy 技术适用的分类单元科属种菌株技术方法限制性酶切片段长度多态性(RFLP)低频酶切片断分析(LFFA, FFOE)核糖体DNA PCR扩增酶切长度多态性血清学方法DNA 扩增 (AFLP, AP-PCR, rep-PCR, ARDRA)噬菌型多

9、位点酶电泳分析全细胞蛋白质电泳图谱DNA杂交 G + C mol %tDNA-PCR化学分类标记细胞脂肪酸组成(FAME)细胞壁结构表型特征分析rRNA 序列分析DNA 探针DNA 序列分析Database and computer softwareDatabaseGenbank（NCBI）：info ncbi. nlm. nih. gov EMBL:fasta embl-heidelberg.de Software for drawing dendrogram or phylogenetic treeGCG(genetic computer Group package )GelcomparC

10、lustralXReferences Bergeys Manual of Determinative BacteriologyProvides identification schemes for identifying bacteria and archaeaMorphology, differential staining, biochemical tests Bergeys Manual of Systematic BacteriologyProvides phylogenetic information on bacteria and archaeaBased on rRNA sequ

11、encing Approved Lists of Bacterial NamesLists species of known prokaryotesBased on published articlesProkaryotes1. List the taxonomic hierarchy of classification.2. What is the three domain classification system ? Draw a simple dendrogram to show their phylogenetic relationship among the organisms.3. There are 50 strains isolated from the root nodules of peanut. These strains are slow-growing