第三章原核微生物细菌和古生菌

1、第3章 原核(yun h)生物：细菌和古生菌Procaryotes: The Bacteria and ArchaeaA Microbiology Course by Bo CHEN (e-mail: qqchen36)共四十五页CONTENTSSurvey of Procaryotic Cell StructureBacterial External StructureBacterial Internal StructureBacterial Shapes, Arrangements, and SizesBacterial Identification and Classification

2、SystemsUnusual Procaryotic Groups共四十五页SECTION 1 Survey of Procaryotic Cell Structure(原核细胞的结构(jigu)概览)共四十五页Survey of procaryotic cell structure (a typical rod-shaped bacterium). General structure; Special structure10986754123中间体：1.增加(zngji)表面积；2.类似细胞器功能糖被储藏(chcng)颗粒菌毛性毛鞭毛类核共四十五页Survey of Procaryotic

3、Cell StructureProcaryotic cell (原核细胞)Appendages (附体)Cytoplasm (细胞质) Cell envelope (细胞(xbo)包被)Flagella (鞭毛(binmo) Pili (性毛) Fimbriae (菌毛)Glycocalyx (糖被) Cell wall Cell membraneCell pool Granules (贮藏颗粒) Ribosomes Nucleoid (类核)/chromosomeCapsules (荚膜) Slime layers (粘液层)External structureInternal struct

4、ure共四十五页SECTION 2 Bacterial External Structure (细菌的外部(wib)结构)共四十五页2.1 APPENDAGES: CELL EXTENSIONS (附体：细胞(xbo)的延伸)Appendages (附体)Flagella (鞭毛(binmo) motility (运动性)Pili (性毛) DNA transfer (DNA转移)Fimbriae (菌毛) adhesion (粘附)共四十五页Flagella Bacterial Propellers(鞭毛(binmo) 细菌的螺旋桨)Flagellum: Latin, whip20 nm i

5、n diameter, 1-70 nm in lengthFunction: motility, or self-propulsion, to swim in aqueous habitatAll spirilla (螺旋菌), about half of the bacilli (杆菌(gnjn), and a small number of cocci (球菌) are flagellated共四十五页Fig.4.2 Structure of flagella. (a) Electron micrograph of basal bodies and filaments (at arrows

6、) of bacterial flagella (66,000). (b) Details of the basal body in a gram-negative cell.Form of flagella鞭毛(binmo)丝鞭毛(binmo)鞘 (sheath)基体!共四十五页Filament, a helical structure composed of proteins flagellin (鞭毛(binmo)丝, 由鞭毛蛋白构成), 20 nm in diameter, 1-70 nm in length共四十五页Fig.4.3 Electron micrographs depic

7、ting types of flagellar arrangementsTypes of flagella (三种(sn zhn)类型)1. Monotrichous (a. 单生)2. Lophotrichous (b. 单端丛生) Amphitrichous (c. 两端丛生)3. Peritrichous (d. 周生)Note: 端生=极生 (polar flagella)Gr. hairy共四十五页Motility (运动性)运动方式(fngsh)不同于鞭子的抽动，而是360旋转 (rotation)Velocity: Pseudomonas aeruginosa (铜绿假单胞菌):

8、 polar, can swim 4.4 mm/min (2,000-fold the length of the bacterium) E. coli: peritrichous (周生), 1 mm/minFunction of flagella共四十五页Fig.4.5 The operation of flagella and the mode of locomotion in bacetria with polar and peritrichous flagella. Direction of rotation:Counterclockwise: swim forward (run)

9、Clockwise: stop (tumble 翻滚(fngn)共四十五页Motility Detectiona. Stab inoculation into a semisolid medium (半固体穿刺培养)(a)(b)b. Hanging drop slide (悬滴法)Motile: the cell swims and progresses from one point to another; Nonmotile: the cell oscillates (振荡) in the same space (Brownian movement).共四十五页鞭毛(binmo)与趋向性Th

10、ey can detect and move in response to chemical and light signalsChemotaxis (趋化性) Positive: favorable chemical stimulus (nutrients, move forward) Negative: harmful chemical stimulus (move away)Phototaxis (趋光性) some photosynthetic bacteria共四十五页Fig.4.9 Three bacteria in the process of conjugation (bact

11、erial mating 细菌接合(jih)作用).Pili (性毛)Sex pilusFound only on G-bacteriaFunction: DNA Transfer共四十五页共四十五页Fig.4.8 Form and function of bacetrial fimbriaeFunction: adhesion (粘附(zhn f) attachment)Relationship between Fimbriae and pathogenicity Gonococcus (淋球菌)侵染(qn rn)泌尿道 E. coli侵染肠道 Mutation and pathogenic

12、ityFimbriae (菌毛)(绒毛)共四十五页2.2 THE CELL ENVELOPE (细胞(xbo)包被)123共四十五页Glycocalyx (糖被) 糖被：是包裹在某些细菌(xjn)细胞壁外的一层胶状物质 多种名称：多糖-多肽复合物，糖萼，糖被 两类： 荚膜 (b)：结构比较紧密，有固定形态，固定在壁上 粘液层 (a)：结构比较松散，无固定形态，未固定在壁上共四十五页不动杆菌属根瘤菌属Capsule (荚膜)* the cell proper: the proper cell 严格意义上的(真正的，本身(bnshn)的)细胞共四十五页 光滑(gung hu)型菌落：S型，smoo

13、th type，mucoid (粘液样的) ，有荚膜 粗糙型菌落：R型，rough type，noncoid ，无荚膜根据有无(yu w)荚膜，菌落分为2种类型：共四十五页荚膜的功能(gngnng)保护 (protection)： 极端环境下（e.g.干旱、贫瘠）防止水分和营养丢失；防止噬菌体的吸附和裂解；防止宿主白细胞吞噬：有荚膜的肺炎链球菌有致病性，引起(ynq)肺炎，如发生突变，无荚膜的肺炎链球菌致病性大大下降营养补充 (nutrient supplement)： 荚膜多糖、多肽粘附 (adhesion)： 定位作用，菌胶团（荚膜包裹在细胞群上，e.g.动胶菌属Zoogloea）共四十五

14、页Fig.4.13 Biofilm. Staphylococcus aureus (金葡) cells attached to a catheter (导尿管) by a slime secretion.共四十五页Application of Capsules肠膜状明串株菌 糖被中提取葡聚糖制备“代血浆”野油菜黄单胞菌 粘液(zhn y)层中提取胞外多糖 黄原胶新型粘着剂？共四十五页Cell Wall (细胞壁)壁与墙的区别(qbi)共四十五页Cell Wall (细胞壁)Location: the second layer of cell envelope, between glycocal

15、yx and cell membrane.Composition: mainly composed of peptidoglycan (肽聚糖), the unique component of eubacteria cell wall (注意(zh y)：真细菌特有，古细菌没有).Function: keep the cell shape, provide osmotic (渗透压) protection.共四十五页1. Glycan chain (聚糖链)2. Tetrapeptide side chain (四肽侧链)3. Peptide interbridge (肽间桥)(G)(M)P

16、eptidoglycan (肽聚糖)网络状大分子共四十五页(N-乙酰氨基(nj)葡萄糖)(N-乙酰胞壁酸)Glycan chain (聚糖链)Lactic acid糖苷键共四十五页Glycan chain (聚糖链)G： N-乙酰氨基葡萄糖M：N-乙酰胞壁酸聚糖链：每条链10-65个二糖单位 (-G-M-)金葡：只有(zhyu)9个二糖单位地衣芽胞杆菌：79个二糖单位共四十五页S.aureus (G+)Peptide chain(G+)=O短肽链：包括(boku)四肽侧链和肽间桥penicillin acting site共四十五页Peptide Chain (肽链)四肽侧链：4个aa按L型与

17、D型交替方式连接，在金葡（G+）中为L-Ala-D-Glu-L-Lys-D-Ala，D-型aa在细菌细胞壁之外很少出现肽间桥：金葡中为5个Gly，不同细菌可能(knng)肽聚糖不同（已知超过100种，肽聚糖多样性），主要是肽间桥组成aa不同。青霉素：作用于肽间桥Gly与四肽侧链D-Ala之间（不同抗生素作用效果不同，肽间桥组成多样性造成，见上图）共四十五页Lactic acid糖苷键Tetrapeptide side chain (四肽侧链,G)N-乙酰胞壁酸乙酰氨基(nj)葡萄糖内消旋二氨基(nj)庚二酸, G-独有G四肽侧链与G+组成有所不同共四十五页m-DAP (内消旋二氨基(nj)庚二

18、酸,G)与Lysine (赖氨酸,G+)共四十五页Peptidoglycan (肽聚糖)网络状大分子复合物 由3部分(b fen)组成：1. Glycan chain (聚糖链)2. Tetrapeptide side chain (四肽侧链)3. Peptide interbridge (肽间桥)单层多层: 枯草杆菌20层共四十五页肽聚糖网状结构的特点(tdin)Rigidity 刚性：决定和保持细胞的形状Integrity 完整性：保护细胞不致因渗透压破裂Meshwork 网状结构：物质交换 (营养吸收(xshu)、废物排出)*交联度：决定网孔大小与结构强度 (交联度越大，网孔越小，结构强

19、度越大)共四十五页Mechanisms of Antibiotics and Lysozymes共四十五页(N-乙酰氨基(nj)葡萄糖)(N-乙酰胞壁酸)Lysozyme (溶菌酶)糖苷键Lysozyme- sensitive bond, lysozyme hydrolyzing site共四十五页Penicillin target: binds and blocks peptidaseC=OS.aureus (G+)Penicillin (青霉素)共四十五页The mode of action of penicillins on the bacterial cell wallPenicillins bind and block peptidases catalyzing the cross-link of glycan molecules, thereby interrupting the completion of the cell wall.“散架(sn ji)”共四十五