细菌的生物学性状

1、第二章第二章 微生物的生物学性状微生物的生物学性状 (thethe biological biological of microbiology)of microbiology)微生物（微生物（microorganism）包括）包括 细菌、支原体、立克次体、衣原体、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、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。染色特性与结构、生长繁殖与培养、理化性状与分类。第一节第一节 细细 菌菌(bacterium)细菌细菌(bacterium)的定义的定义

2、: 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、亦无核仁和核膜膜,仅有核蛋白体的原核单细胞微生物仅有核蛋白体的原核单细胞微生物(prokaryote single-cell microorganism)。 细菌的基本特点细菌的基本特点(bacterias basic character)：具有细胞壁具有细胞壁(cell wall)、原始的核质、原始的核质(original karyoplasm)，以二分裂方，以二分裂方式繁殖和对抗生素等药物敏感式繁殖和对抗生素等药物敏感(sensitive to antibiotic) 。一、一、 细菌的

3、大小与形态细菌的大小与形态 (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.lcocci: sphere, 1m lbacilli: rods , 0.5-1 m in width -3 m in length lspiral bacteria: 13

4、m in length and 0.3-0.6 m in width.细菌的大小细菌的大小(size of bacteria) 光学显微镜光学显微镜(light microscope); 测量单位测量单位:微米微米(m) 细菌的观察细菌的观察(optical methods)：细菌本身为无色半透明，：细菌本身为无色半透明，需经过染色需经过染色(staining)才能观察到细菌的形态才能观察到细菌的形态(morphology)（轮廓（轮廓figure）和其结构）和其结构(structure). 细菌的形态细菌的形态(morphology) :三大类形态三大类形态球菌球菌(coccus)、 杆菌杆

5、菌(bacillus)和螺形菌和螺形菌(spirala bacterium)三大类三大类1、球菌、球菌(coccus):0.81.2m,外观呈圆球性或近似球性外观呈圆球性或近似球性(肾形、肾形、豆形等豆形等)(often occur in characteristic aggregates (pairs, often occur in characteristic aggregates (pairs, chains, tetrads, clusters, etc.).chains, tetrads, clusters, etc.). 双球菌双球菌(diplococcus):一个平面上分裂一个平

6、面上分裂,如脑膜炎球菌、肺炎球菌。如脑膜炎球菌、肺炎球菌。.链球菌链球菌(streptococcus):一个平面上分裂一个平面上分裂,分裂后多个菌体粘连分裂后多个菌体粘连成链状。如溶血性链球菌成链状。如溶血性链球菌(hemolytic streptococcus) 。四联球菌四联球菌八叠球菌八叠球菌. 四联球菌四联球菌(retrad)、 八叠球菌八叠球菌(sarcina).葡萄球菌葡萄球菌(staphylococcus):多个不规则的平面上分裂多个不规则的平面上分裂,粘连粘连成葡萄串状。如金黄色葡萄球菌成葡萄串状。如金黄色葡萄球菌(staphyloccus aurea)。杆菌杆菌(bacill

7、us) (bacilli, or cylindrical or rod-bacilli, or cylindrical or rod-shapes cell)sshapes cell)s 外形呈杆形，其大小、长短及粗细不一致，（最大的如炭疽外形呈杆形，其大小、长短及粗细不一致，（最大的如炭疽杆菌）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）。（如结核分支杆菌）。 球杆菌球杆菌棒状杆菌（如白喉杆菌棒状杆菌（如白喉杆菌 diphtheria bacillus）分支杆菌（如结核分支杆菌分支杆菌（如结核分支杆菌

8、tubercle bacillus）螺形菌螺形菌(spirala bacterium)(spiral or curved formsspiral or curved forms )弧菌弧菌(vibrio)：只有一个弯曲（菌体长：只有一个弯曲（菌体长23m），呈弧），呈弧状或逗点状状或逗点状（图（图1）螺菌螺菌(spirillum)：有数个弯曲（菌体较长：有数个弯曲（菌体较长36m）（图（图2）（图（图1）（图（图2）.总结总结(summarize) 细菌的形态受温度细菌的形态受温度(temperature)、ph、离子、离子和培养时间等因素的影响。（选择生长繁殖的和培养时间等因素的影响。（选择

9、生长繁殖的对对数期数期观察其大小及形态为宜）观察其大小及形态为宜）structure of bacteriaparticular structures capsule 荚膜荚膜flagella 鞭毛鞭毛pili 菌毛菌毛spore 芽胞芽胞细细 菌菌 的的 结结 构构(bacterias structure) 细菌的基本结构细菌的基本结构( structure)（细细胞壁、细胞膜、细胞质、核质、核蛋白体和质粒）胞壁、细胞膜、细胞质、核质、核蛋白体和质粒） 细菌的特殊结构细菌的特殊结构(particular structure)（荚（荚膜、鞭毛、菌毛、芽孢）膜、鞭毛、菌毛、芽孢） 二、细菌的基本

10、结构二、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）。白体和质粒）和特殊结构（荚膜、鞭毛、菌毛、芽孢）。(cell wall、cell membranecell membrane、cytoplasm cytoplasm 、nucleics acidsnucleics acids、plasmidplasmid) ) (一一)细胞壁细胞壁(cell wall):一种膜状结构一种膜状结构;主要组分是主要组分是肽聚糖肽聚糖(peptido

11、glycan)(又称粘肽又称粘肽mucopeptide、糖肽或、糖肽或胞壁质胞壁质),为细菌细胞壁（原核生物细胞）所特有的物质。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：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膜壁分离法、特殊染色法以及电子显微镜观察等方法察等方法1.g+菌菌( g r a m - p o s i t i v e c e l l w a l l )g r a m - p o s i t i v e c e l l w a l l )的肽聚糖的肽聚糖(peptidoglycan):三部分组成三部分组成(1) 聚糖骨架：聚糖骨架：由由n-乙酰葡糖胺

12、和乙酰葡糖胺和n-乙酰胞壁两种氨基糖乙酰胞壁两种氨基糖交替间隔排列组成（经交替间隔排列组成（经-1,4糖苷键糖苷键联结而成）联结而成）(2) 四肽侧链四肽侧链:由由l-丙氨酸、丙氨酸、d-谷氨酸、谷氨酸、l-赖氨酸、赖氨酸、d-丙氨丙氨酸组成。酸组成。(3) 五肽交链桥：五肽交链桥：五个苷氨酸组成五个苷氨酸组成五肽交链桥将相临的两条聚糖骨架连接起来成三维立体结构。五肽交链桥将相临的两条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

13、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, and peptidoglycolipids) are covalently attached to the peptidoglycan.mmmmmmmmmmmmggggggggggggabc

14、dabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdg+ 菌的肽聚糖结构： g：n-乙酰葡萄糖胺乙酰葡萄糖胺 m：n-乙酰胞壁酸乙酰胞壁酸2.g的肽聚糖的肽聚糖(peptidoglycan):二部分组成二部分组成(1) 聚糖骨架聚糖骨架:同同g+菌菌(2)四肽侧链四肽侧链:第三位氨基酸第三位氨基酸(l-赖氨酸赖氨酸)被二氨基庚被二氨基庚二酸二酸(dap)取代取代g菌没有五肽交链桥菌没有五肽交链桥,故只形成二维结构故只形成二维结构gram-negative cell wall in contrast, the peptidoglycan layer in g

15、ram-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 is

16、 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.丙mgggdapmg丙丙丙谷谷dapg-菌的肽聚糖结构dap：二氨基庚二酸：二氨基庚二酸3.g

17、+菌细胞壁的特殊组分菌细胞壁的特殊组分():磷壁酸磷壁酸(teichoic acid)及表面特殊蛋白及表面特殊蛋白组分组分(1)壁磷壁酸壁磷壁酸:通过磷脂与肽聚糖的通过磷脂与肽聚糖的m共价连结共价连结膜磷壁酸膜磷壁酸(又称脂磷壁酸又称脂磷壁酸lta):末端糖脂与细胞膜外层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。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，是磷壁酸的抗原性很强，是g+菌的重要表面抗原，与菌的重要表面抗原，与血清学分型有关。血清学分型有关。g+ 菌的特殊

18、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磷脂蛋白质细胞壁脂质双层细胞膜肽聚糖微孔蛋白 脂多糖脂蛋白营养结合蛋白外膜周浆间隙4.g菌细胞壁的特殊组分（菌细胞壁的特殊组分（ ）:外膜外膜(outer membrane)，是，是g-菌菌细胞壁的主要结构。由三部分组成细胞壁的主要结构。由三部分组成脂质双层：脂质双层：中间嵌有蛋白质，称为外膜蛋白中间嵌有蛋白质，称为外膜蛋白（lipoproteinlipoprotein） ，其，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

19、以，止多种大分子物质和青霉素、溶菌酶等进入细胞。所以， g菌对菌对青霉素、溶菌酶以及去污剂和碱性染料等比青霉素、溶菌酶以及去污剂和碱性染料等比g+菌有较大的抵抗力。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有的外膜蛋白还是噬菌体、细菌素和性菌毛的受体 脂质双层脂多糖（脂多糖（lipopolysacchridelipopolysacchride，lpslps） : :由脂质由脂质a,a,核心多核心多糖和特异性多糖组成糖和特异性多糖组成脂质a:内毒素生物活性主要组分,无种属 特异性核心多糖:有属特异性特异多糖: g-菌的菌体抗原(o抗原), 有种特异性 gram negativ

20、e bacterialmajor permeability barrier(通透性屏障）通透性屏障） lspace between inner and outer membraneperiplasmic space（周浆间隙）（周浆间隙）vstore degradative enzymes（降解酶）（降解酶）lgram positive bacteria lno periplasmic spaceouter membrane5.细胞壁细胞壁(cell wall)的功能的功能(function):(1) 维持菌体的固有形态及抵抗低渗环境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

21、换；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（如有关（如 磷壁酸、磷壁酸、m蛋白）。蛋白）。(4) 参与细菌的致病：参与细菌的致病：lta具有粘附致病作用具有粘附致病作用; m蛋白具有蛋白具有抗吞噬作用，并对抗吞噬作用，并对tcel及及bcel等免疫细胞有生物活性作用。等免疫细胞有生物活性作用。functions of cell wall maintaining the cells characteristic shape- the rigid wall compensates for the flexibil

22、ity of the phospholipid membrane and keeps the cell from assuming a spherical shape countering the effects of osmotic pressure providing attachment sites for bacteriophages providing a rigid platform for surface appendages- flagella, fimbriae, and pili all emanate from the wall and extend beyond it

23、play an essential role in cell division be the sites of major antigenic determinants of the cell surface。 resistance of antibiotics 6细胞壁缺陷型细菌（细胞壁缺陷型细菌（l型细菌型细菌l-formed bacteria） ：(1)形成原因形成原因:肽聚糖结构受理化或生物因素肽聚糖结构受理化或生物因素(例青霉例青霉素素(penicillin)和溶菌酶和溶菌酶(lysozyme) )的破坏及合成被的破坏及合成被抑制抑制wall-less forms of bacter

24、ia. 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 bacteria that can not replicate a

25、re 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) 形态形态:多型性多型性;均为均为g阴性；去除诱导因素后，阴性；去除诱导因素后，l型可型可回复为原菌回复为原菌l型葡萄球菌葡萄球菌(3)培养特性培养特性(prop

26、erties of culturing):需提高培养基的渗透压需提高培养基的渗透压(补充补充3-5%nacl,10-20%的蔗的蔗糖糖;另加另加10-20%的人或马血清的人或马血清);菌落特点菌落特点:荷包蛋样菌落或在液体培养基中呈疏松的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。絮状颗粒、沉于管底而培养基澄清。原菌菌落原菌菌落荷包蛋样荷包蛋样l型菌落型菌落(4)致病性致病性(pathogenesis): 通常引起通常引起慢性感染慢性感染，如尿路感染，如尿路感染（多见）（多见）、骨、骨髓炎、心内膜炎髓炎、心内膜炎(一般培养往往阴性一般培养往往阴性) ；常在；常在使用使用

27、了作用于细胞壁的抗菌药物后发生了作用于细胞壁的抗菌药物后发生（二）细胞膜（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分裂有关等作用 （三）细胞质（三）细胞质 (cytoplasm)1.核蛋白体核蛋白体(ribosome):细菌合成蛋白质的场所细菌合成蛋白质的场所;70%rna+30%蛋白质蛋白质;70s(50s+30s): ribosomal are 70s with subunits 30s ribosomal are 70s with subunits 30s (16s rrna) and 5

28、0s (5s & 23s rrna(16s rrna) and 50s (5s & 23s rrna) )链霉素和红霉素作用于链霉素和红霉素作用于50s及及30s亚基亚基,干扰蛋白质的合干扰蛋白质的合成成2.质粒质粒(plasmid): 染色体外的遗传物质；染色体外的遗传物质； 闭合环状双股闭合环状双股dna,控制细菌的某些特定遗传性状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。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

29、药性、细菌素产生、毒素质粒控制的形状有：性菌毛生成、耐药性、细菌素产生、毒素形成等。形成等。plasmidplasmids are small，circular/line，extrachromosomal，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 cellu

30、lar survival. linclusions are aggregates of various compounds that are normally 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.granulosegranulo

31、se extrachromosomal dna multiple copy number coding pathogenesis and antibiotic resistance factors bacterial replication3.胞质颗粒胞质颗粒(cytoplasmic granules,又称内含物又称内含物) 大多为储藏的营养物质大多为储藏的营养物质;主要成分主要成分:rna和多偏磷酸和多偏磷酸(嗜碱性嗜碱性强强,甲基兰染色成异染颗粒甲基兰染色成异染颗粒,亦称纡回体。亦称纡回体。在白喉杆菌中称极体在白喉杆菌中称极体)(五五) 核核 质质(nuclear material)1.

32、1. size and shapes of bacterialsize and shapes of bacterialthe shapesofthe shapesof medically important bacteria are classified into the medically important bacteria are classified into the following general forms: following general forms: (1)(1)coccicocci, or spherical cells; often occur in charact

33、eristic , or spherical cells; often occur in characteristic aggregates (pairs, chains, tetrads, clusters, etc.).aggregates (pairs, chains, tetrads, clusters, etc.).(2)(2)bacilli, or cylindrical or rod-shapes cells;bacilli, or cylindrical or rod-shapes cells;(3)(3)spiral or curved forms.spiral or cur

34、ved forms.conclusionconclusion2. 2. bacterial cell structurebacterial cell structure2.1 basic structures of bacterial2.1 basic structures of bacterial2.1.1 cell wall2.1.1 cell wall most bacteria of medical importance possess one of most bacteria of medical importance possess one of two basic types o

35、f cell wall architecture, which are two basic types of cell wall architecture, which are referred to as gram-positive or gram-negative. the one referred to as gram-positive or gram-negative. the one component common to both walls is a large polymer, component common to both walls is a large polymer,

36、 commonly referred to as peptidoglycan or mureincommonly referred to as peptidoglycan or murein. .2.1.1.1 2.1.1.1 gram-positive cell wallgram-positive cell wall most gram-positive bacteria have a relatively thick most gram-positive bacteria have a relatively thick (about 20 to 80 nm), continuous cel

37、l wall, which is (about 20 to 80 nm), continuous cell wall, which is composed largely of peptidoglycan (also known as composed largely of peptidoglycan (also known as mucopeptide or murein). in thick cell walls, other cell mucopeptide or murein). in thick cell walls, other cell wall polymers (such a

38、s the teichoic acids, wall polymers (such as the teichoic acids, polysaccharides, and peptidoglycolipids) are covalently polysaccharides, and peptidoglycolipids) are covalently attached to the peptidoglycanattached to the peptidoglycan. .2.1.1.2 gram-negative cell wall2.1.1.2 gram-negative cell wall

39、 in contrast, the peptidoglycan layer in gram-negative bacteria in contrast, the peptidoglycan layer in gram-negative bacteria is thin (about 5 to 10 nm thick); in e coli, the peptidoglycan is is thin (about 5 to 10 nm thick); in e coli, the peptidoglycan is probably only a monolayer thick. outside

40、the peptidoglycan layer probably only a monolayer thick. outside the peptidoglycan layer in the gram-negative envelope is an outer membrane structure in the gram-negative envelope is an outer membrane structure (about 7.5 to 10 nm thick). in most gram-negative bacteria, this (about 7.5 to 10 nm thic

41、k). in most gram-negative bacteria, this membrane structure is anchored noncovalently to lipoprotein membrane structure is anchored noncovalently to lipoprotein molecules (brauns lipoprotein), which, in turn, are covalently molecules (brauns lipoprotein), which, in turn, are covalently linked to the

42、 peptidoglycan. the lipopolysaccharideslinked to the peptidoglycan. the lipopolysaccharides of the gram- of the gram-negative cell envelope form part of the outer leaflet of the outer negative cell envelope form part of the outer leaflet of the outer membrane structure.membrane structure.2.1.2 cell membrane2.1.2 cell membrane oxidative phosphorylation(氧化磷酸化） occurs at cell membrane (since there are no mitochondria). cell membranethe cell wall is outside of cell membrane rigid, protecting cell from osmotic lysis.cell wall2.1.