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1、第二章 微生物的生物学性状(The biological Morphology of microbiology),微生物（microorganism）包括 细菌、支原体、立克次体、衣原体、螺旋体和放线菌、病毒以及真菌。微生物的生物学性状包括其形态、染色特性与结构、生长繁殖与培养、理化性状与分类。,第一节 细 菌(bacterium),细菌(bacterium)的定义:细菌是一种形体微小、结构简单、无成形细胞核、亦无核仁和核膜,仅有核蛋白体的原核单细胞微生物(prokaryote single-cell microorganism)。,细菌的基本特点(bacterias basic charac
2、ter)：具有细胞壁(cell wall)、原始的核质(original karyoplasm)，以二分裂方式繁殖和对抗生素等药物敏感(sensitive to antibiotic)。,一、细菌的大小与形态(Size and shapes of bacterial),SIZE OF BACTERIA,Unit for measurement:Micron or micrometer,m:1m=10-3mm Size:Varies with kinds of bacteria,and also related to their age and external environment.,Coc
3、ci:sphere,1m Bacilli:rods,0.5-1 m in width-3 m in length Spiral bacteria:13 m in length and 0.3-0.6 m in width,.细菌的大小(size of bacteria)光学显微镜(light microscope);测量单位:微米(m),细菌的观察(optical methods)：细菌本身为无色半透明，需经过染色(staining)才能观察到细菌的形态(morphology)（轮廓figure）和其结构(structure),.细菌的形态(morphology):三大类形态球菌(coccus
4、)、杆菌(bacillus)和螺形菌(spirala bacterium)三大类,1、球菌(coccus):0.81.2m,外观呈圆球性或近似球性(肾形、豆形等)(often occur in characteristic aggregates(pairs,chains,tetrads,clusters,etc.).双球菌(diplococcus):一个平面上分裂,如脑膜炎球菌、肺炎球菌。,.链球菌(streptococcus):一个平面上分裂,分裂后多个菌体粘连成链状。如溶血性链球菌(hemolytic streptococcus)。,四联球菌,八叠球菌,.四联球菌(retrad)、八叠球菌
5、(sarcina),.葡萄球菌(staphylococcus):多个不规则的平面上分裂,粘连成葡萄串状。如金黄色葡萄球菌(staphyloccus aurea)。,杆菌(bacillus)(bacilli,or cylindrical or rod-shapes cell)s 外形呈杆形，其大小、长短及粗细不一致，（最大的如炭疽杆菌）球杆菌、链杆菌、梭杆菌、棒状杆菌（如白喉杆菌）及分支杆菌（如结核分支杆菌）。,球杆菌,棒状杆菌（如白喉杆菌 diphtheria bacillus）,分支杆菌（如结核分支杆菌tubercle bacillus）,螺形菌(spirala bacterium)(spi
6、ral or curved forms)弧菌(vibrio)：只有一个弯曲（菌体长23m），呈弧状或逗点状（图1）螺菌(spirillum)：有数个弯曲（菌体较长36m）（图2）,（图1）,（图2）,.总结(summarize)细菌的形态受温度(temperature)、PH、离子和培养时间等因素的影响。（选择生长繁殖的对数期观察其大小及形态为宜）,Structure of Bacteria,Particular structures capsule 荚膜flagella 鞭毛pili 菌毛spore 芽胞,Essential structures cell wall 细胞壁cell memb
7、rane 细胞膜Cytoplasm 细胞质nuclear material 核质,细 菌 的 结 构(bacterias structure),细菌的基本结构(Essential structure)（细胞壁、细胞膜、细胞质、核质、核蛋白体和质粒）细菌的特殊结构(Particular structure)（荚膜、鞭毛、菌毛、芽孢）,二、细菌的基本结构(basic structure)细菌的结构分基本结构（细胞壁、细胞膜、细胞质、核质、核蛋白体和质粒）和特殊结构（荚膜、鞭毛、菌毛、芽孢）。(Cell Wall、Cell Membrane、Cytoplasm、Nucleics acids、plas
8、mid),(一)细胞壁(cell wall):一种膜状结构;主要组分是肽聚糖(peptidoglycan)(又称粘肽mucopeptide、糖肽或胞壁质),为细菌细胞壁（原核生物细胞）所特有的物质。,细胞壁的观察方法：膜壁分离法、特殊染色法以及电子显微镜观察等方法,1.G+菌(Gram-Positive Cell Wall)的肽聚糖(peptidoglycan):三部分组成(1)聚糖骨架：由N-乙酰葡糖胺和N-乙酰胞壁两种氨基糖交替间隔排列组成（经-1,4糖苷键联结而成）(2)四肽侧链:由L-丙氨酸、D-谷氨酸、L-赖氨酸、D-丙氨酸组成。(3)五肽交链桥：五个苷氨酸组成五肽交链桥将相临的两条
9、聚糖骨架连接起来成三维立体结构。,Gram-Positive Cell Wall Most Gram-positive bacteria have a relatively thick(about 20 to 80 nm),continuous cell wall,which is composed largely of peptidoglycan(also known as mucopeptide or murein).In thick cell walls,other cell wall polymers(such as the teichoic acids,polysaccharides
10、,and peptidoglycolipids)are covalently attached to the peptidoglycan.,M,M,M,M,M,M,M,M,M,M,M,M,G,G,G,G,G,G,G,G,G,G,G,G,G+菌的肽聚糖结构：,G：N-乙酰葡萄糖胺 M：N-乙酰胞壁酸,2.G的肽聚糖(peptidoglycan):二部分组成(1)聚糖骨架:同G+菌(2)四肽侧链:第三位氨基酸(L-赖氨酸)被二氨基庚二酸(DAP)取代G菌没有五肽交链桥,故只形成二维结构,Gram-Negative Cell Wall In contrast,the peptidoglycan la
11、yer in Gram-negative bacteria is thin(about 5 to 10 nm thick);in E coli,the peptidoglycan is probably only a monolayer thick.Outside the peptidoglycan layer in the Gram-negative envelope is an outer membrane structure(about 7.5 to 10 nm thick).In most Gram-negative bacteria,this membrane structure i
12、s anchored noncovalently to lipoprotein molecules(Brauns lipoprotein),which,in turn,are covalently linked to the peptidoglycan.The lipopolysaccharides of the Gram-negative cell envelope form part of the outer leaflet of the outer membrane structure.,G,G,G-菌的肽聚糖结构,DAP：二氨基庚二酸,3.G+菌细胞壁的特殊组分(Special com
13、ponents of Gram positive cell wall):磷壁酸(teichoic acid)及表面特殊蛋白组分(1)壁磷壁酸:通过磷脂与肽聚糖的M共价连结膜磷壁酸(又称脂磷壁酸LTA):末端糖脂与细胞膜外层的糖脂共价连结。另外，与细胞壁其他成分协同，能粘附在人体细胞表面，与细菌的致病性有关。,磷壁酸的抗原性很强，是G+菌的重要表面抗原，与血清学分型有关。,G+菌的特殊组分:磷壁酸及一些表面蛋白,膜磷壁酸,壁磷壁酸,肽聚糖,细胞膜,细胞壁,4.G菌细胞壁的特殊组分（Special components of Gram negative cell wall）:外膜(outer me
14、mbrane)，是G-菌细胞壁的主要结构。由三部分组成,脂质双层：中间嵌有蛋白质，称为外膜蛋白（lipoprotein），其中包括孔蛋白，具有物质交换作用，并具有通透性屏障作用，能阻止多种大分子物质和青霉素、溶菌酶等进入细胞。所以，G菌对青霉素、溶菌酶以及去污剂和碱性染料等比G+菌有较大的抵抗力。有的外膜蛋白还是噬菌体、细菌素和性菌毛的受体,脂多糖（Lipopolysacchride，LPS）:由脂质A,核心多糖和特异性多糖组成,Gram negative bacteriamajor permeability barrier(通透性屏障）space between inner and oute
15、r membraneperiplasmic space（周浆间隙）store degradative enzymes（降解酶）Gram positive bacteria no periplasmic space,Outer Membrane,5.细胞壁(cell wall)的功能(function):(1)维持菌体的固有形态及抵抗低渗环境;(2)参与菌体内外物质交换；(3)带有多种抗原，诱发机体产生免疫应答并与血清分型有关（如磷壁酸、M蛋白）。(4)参与细菌的致病：LTA具有粘附致病作用;M蛋白具有抗吞噬作用，并对Tcel及Bcel等免疫细胞有生物活性作用。,Functions of Cel
16、l Wall,Maintaining the cells characteristic shape-the rigid wall compensates for the flexibility of the phospholipid membrane and keeps the cell from assuming a spherical shape Countering the effects of osmotic pressureProviding attachment sites for bacteriophagesProviding a rigid platform for surfa
17、ce appendages-flagella,fimbriae,and pili all emanate from the wall and extend beyond itPlay an essential role in cell divisionBe the sites of major antigenic determinants of the cell surface。Resistance of Antibiotics,6细胞壁缺陷型细菌（L型细菌L-formed bacteria）：(1)形成原因:肽聚糖结构受理化或生物因素(例青霉素(penicillin)和溶菌酶(lysozym
18、e)的破坏及合成被抑制,Wall-less forms of Bacteria.,When bacteria are treated with 1)enzymes that are lytic for the cell wall e.g.lysozyme or 2)antibiotics that interfere with biosynthesis of peptidoglycan,wall-less bacteria are often produced.Usually these treatments generate non-viable organisms.Wall-less ba
19、cteria that can not replicate are referred to as spheroplasts(when an outer membrane is present)or protoplasts(if an outer membrane is not present).Occasionally wall-less bacteria that can replicate are generated by these treatments(L forms).,(2)形态:多型性;均为G阴性；去除诱导因素后，L型可回复为原菌,L型葡萄球菌,葡萄球菌,(3)培养特性(prop
20、erties of culturing):需提高培养基的渗透压(补充3-5%NaCl,10-20%的蔗糖;另加10-20%的人或马血清);菌落特点:荷包蛋样菌落或在液体培养基中呈疏松的絮状颗粒、沉于管底而培养基澄清。,原菌菌落,荷包蛋样L型菌落,(4)致病性(pathogenesis):通常引起慢性感染，如尿路感染（多见）、骨髓炎、心内膜炎(一般培养往往阴性)；常在使用了作用于细胞壁的抗菌药物后发生,（二）细胞膜(cell envelope)参与物质转运、生物合成和分泌、呼吸并与细胞分裂有关等作用,（三）细胞质(cytoplasm)1.核蛋白体(ribosome):细菌合成蛋白质的场所;70%
21、RNA+30%蛋白质;70S(50S+30S):Ribosomal are 70S with subunits 30S(16S rRNA)and 50S(5S&23S rRNA)链霉素和红霉素作用于50S及30S亚基,干扰蛋白质的合成,2.质粒(plasmid):染色体外的遗传物质；闭合环状双股DNA,控制细菌的某些特定遗传性状;能独立进行复制而分配到子代细胞中去;控制的形状非细菌生命活动所必须;分子生物学研究中重要的载体工具。质粒控制的形状有：性菌毛生成、耐药性、细菌素产生、毒素形成等。,Plasmid,Plasmids are small，circular/line，extrachromo
22、somal，double-stranded DNA molecules。They are capable of self-replication and contain genes that confer some properties，such as antibiotic resistance，virulence factors。Plasmids are not essential for cellular survival.,Inclusions of Bacteria,Inclusions are aggregates of various compounds that are norm
23、ally involved in storing energy reserves or building blocks for the cell.Inclusions accumilate when a cell is grown in the presence of excess nutrients and they are often observed under laboratory conditions.,granulose,Plasmidsextrachromosomal DNAmultiple copy numbercoding pathogenesis and antibioti
24、c resistance factorsbacterial replication,3.胞质颗粒(cytoplasmic granules,又称内含物)大多为储藏的营养物质;主要成分:RNA和多偏磷酸(嗜碱性强,甲基兰染色成异染颗粒,亦称纡回体。在白喉杆菌中称极体),(五)核 质(nuclear material),1.Size and shapes of bacterialThe shapesof medically important bacteria are classified into the following general forms:(1)cocci,or spherical
25、 cells;often occur in characteristic aggregates(pairs,chains,tetrads,clusters,etc.).(2)bacilli,or cylindrical or rod-shapes cells;(3)spiral or curved forms.,conclusion,2.Bacterial Cell Structure2.1 Basic Structures of Bacterial2.1.1 Cell Wall Most bacteria of medical importance possess one of two ba
26、sic types of cell wall architecture,which are referred to as Gram-positive or Gram-negative.The one component common to both walls is a large polymer,commonly referred to as peptidoglycan or murein.,2.1.1.1 Gram-Positive Cell Wall Most Gram-positive bacteria have a relatively thick(about 20 to 80 nm
27、),continuous cell wall,which is composed largely of peptidoglycan(also known as mucopeptide or murein).In thick cell walls,other cell wall polymers(such as the teichoic acids,polysaccharides,and peptidoglycolipids)are covalently attached to the peptidoglycan.,2.1.1.2 Gram-Negative Cell Wall In contr
28、ast,the peptidoglycan layer in Gram-negative bacteria is thin(about 5 to 10 nm thick);in E coli,the peptidoglycan is probably only a monolayer thick.Outside the peptidoglycan layer in the Gram-negative envelope is an outer membrane structure(about 7.5 to 10 nm thick).In most Gram-negative bacteria,t
29、his membrane structure is anchored noncovalently to lipoprotein molecules(Brauns lipoprotein),which,in turn,are covalently linked to the peptidoglycan.The lipopolysaccharides of the Gram-negative cell envelope form part of the outer leaflet of the outer membrane structure.,Cytoplasm,2.1.2 Cell Membr
30、ane Oxidative phosphorylation(氧化磷酸化）occurs at cell membrane(since there are no mitochondria).,Cell membrane,The cell wall is outside of cell membrane rigid,protecting cell from osmotic lysis.,Cell Wall,2.1.3 Cytoplasm(1)Ribosome（核糖体）:The bacterial cytoplasm is densely packed with 70S ribosome.(2)Pla
31、smid（质粒）:(3)inclusion（内含物）:Inclusions are aggregates（聚合）of various compounds that are normally involved in storing energy reserves or building blocks for the cell.Inclusions accumulate when a cell is grown in the presence of excess nutrients and they are often observed under laboratory conditions.,2
32、.1.4 Nucleics acids Nucleics acids,Ribonucleic acid(RNA)and Deoxyribonucleic acid(DNA),serve as storage units for our hereditary information.DNA can be thought of as a large cookbook with recipes for making every protein in the cell.RNA helps the ribosome translate the information in DNA into protein.,
