一．细菌的形态
1．细菌的个体十分微小；
2．细菌从形态上可分为三类：球菌、杆菌和螺旋菌； 3．所有的细菌都是单细胞个体。
球菌、杆菌和螺旋菌
参看视频演示：
细菌的形态 二．细菌的结构
1．细菌的细胞由细胞壁、细胞质和细胞膜等部分构成，但没有成形的细胞核。
细菌的细胞结构
参看视频演示：
细菌的结构
2．有些细菌生有能够摆动的鞭毛，可以在水中游动；有些细菌的细胞壁外面有一层荚膜，荚膜对细菌有一定的保护作用；有些细菌的细胞内形成一个叫做芽孢的椭圆形休眠体。芽孢的壁很厚，对干旱、低温、高温等恶劣的环境有很强的抵抗力。形成芽孢只是细菌形态结构上的变化，在数量上没有增加，所以芽孢不是生殖细胞。
细菌的鞭毛
细菌的芽胞形态
3．植物细胞和细菌细胞结构的异同点
共同点：都有细胞壁、细胞膜和细胞质。
不同点：植物细胞有成形的细胞核和叶绿体；细菌细胞没有叶绿体，没有成形的细胞核。三．细菌的生殖 1．细菌靠简单的横向分裂进行生殖，这种生殖方式叫做裂殖。2．在适宜的环境下，细菌只需20～30分钟就能繁殖一代。
细菌分裂生殖的电镜图
参看视频演示：
细菌的生殖
四．细菌的营养方式
1．细菌吸收现成的有机物维持生活，这种营养方式为异养。2．异养的细菌分为腐生和寄生：
腐生—依靠分解动植物的遗体，从中吸取有机物来生活。例如枯草杆菌。
寄生—从活的动植物内吸取有机物来生活。例如痢疾杆菌。参看视频演示：
细菌的营养方式
五．细菌对自然界的意义—促进自然界的物质循环
六．细菌与人类的关系
1．大多数种类的细菌对人类是有益的。如醋酸杆菌、乳酸杆菌、棒状杆菌、甲烷细菌和根瘤菌等。
2．少数种类的细菌能够引起人、动物、植物传染病，这样的细菌叫做病原菌。如结核杆菌、肺炎双球菌和软腐病细菌等。
生产奶酪的乳酸菌
根瘤和根瘤菌
肺炎双球菌
菌
参看视频演示1；
结核杆
细菌与人类的关系
参看视频演示2：
病原菌及其预防
返回 第二节
放线菌
一．放线菌的形态和结构特点 1．放线菌的个体十分微小。
2．放线菌由许多菌丝组成一个菌丝体，呈放射状。3．放线菌都是单细胞的个体。
4．放线菌的细胞体内，既没有叶绿素，也没有成形的细胞核。二．放线菌的营养方式和生殖方式
1．营养方式—放线菌的菌丝分为营养菌丝和气生菌丝。它靠营养菌丝吸收营养物质，营腐生生活。2．生殖方式—当生长发育到一定时期时，气生菌丝顶端长出孢子丝，形成孢子。孢子散落出去，在适宜的条件下，萌发成新的菌丝体。三．放线菌与人类的关系
1．有益的方面—有些种类的放线菌，体内能够产生一些抑制或杀死细菌等微小生物的物质，这类物质叫抗生素，可以用来制造许多重要的药品。
2．有害的方面—少数种类的放线菌对人体有害，如有的放线菌能使马铃薯患疮痂病，有的放线菌能使人患脑膜炎。
放线菌图一
放线菌图二
图2-3 2001-1197气生菌丝（1000×）Fig.2-3 Aerial mycelium of 2001-1197（1000×）
A
B
C
图2-4 2001-1197孢子丝及孢子 A：1000×；B：2000×；C：5000×
Fig.2-4 Aerial mycelium with spores of 2001-1197
A: 1000×；B: 2000×；C: 5000×
高氏一号琼脂培养基，20天
葡萄糖天冬素琼脂培养基，20天
苹果酸钙琼脂培养基，20天
燕麦粉琼脂培养基，20天
葡萄糖酵母膏琼脂培养基，20天
酪氨酸琼脂培养基，20天
柴斯纳琼脂培养基，20天
马铃薯块培养基，20天
图2-5 菌株2001-1197的培养特征
Fig.2-5 Culture characteristics of Strain 2001-1197
放线菌手册汇编
放线菌科概述Actinomycetaceae
描述：放线菌科是由Buchanan在1918年创立的该科的一般特征是：革兰氏染色阳性，分支，偏直条状，大多数成员是属于球杆状或者类球形。细胞长度一般小于0.5μm,平均长度在1.7μm到2,9μm之间。群落可能形成丝状体形成类似菌丝体的外形，但是大多数菌落不分枝，而且主要是白色或者灰色，有一些特殊的菌
落会形成深红色、淡红色、棕色、粉色、淡粉或淡黄色。
现在该科根据16s RNA的核酸序列划分出包括五个不同的属：Actinomyces,Actionobaculum,ArcaFigure 1Scanning electron micrograph of Actinomyces israelii
nobacterium,Aobiluncus,Aaribaculum.放线霉菌属Actinomyces 该属包括的种有
A.bovis A.bowdenii A.canis A.cardiffensis A.catuli A.coleocanis A.dentalis A.denticolens A.europaeus A.funkei A.georgiae A.gerencseriae A.graevenitzii A.hongkongensis A.hordeovulneris A.howellii A.humiferus A.hyovaginalis A.israelii A.marimammalium A.meyeri A.naeslundii A.nasicola A.neuii A.odontolyticus A.oricola A.radicidentis A.radingae A.slackii A.streptomycini A.suimastitidis A.suis A.turicensis A.urogenitalis A.vaccimaxillae A.viscosus
一、Actinomyces bovis Actinomyces bovis is a gram-positive, rod-shaped bacterium of the genus Actinomyces.It is the causative agent of Lumpy jaw in cattle, and occasionally causes infections in humans History Actinomyces bovis was first described in 1877 by C.O.Harz, as a microbe within the jaw tissue of cows with lumpy jaw.It was thought to be identical to Actinomyces israelii until 1940, when D.Erikson showed these to be two separate organisms. Figure 2Bovine (sulfa granules)， consisting of colonies of bacteria(Actinomyces bovis)and club-shaped（球棒状的）reaction product, are within a purulent exudate.（脓性渗出物）
二、Actinomyces georgiae
Actinomyces georgiae is a species in the genus of Actinomyces.It is a part of the human periodontal flora（牙周菌群）。三、Actinomyces gerencseriae
Actinomyces gerencseriae(Johnson et al.1990)used to be known as Actinomyces israelii serovar II.Actinomyces gerencseriae was named for the bacteriologist, Mary Ann Gerencser.Figure 3蜘蛛状高度分支的微菌落，26h在36°下培养（1500倍放大）
Figure 4培养于BHIA上的微菌落，显示了一条带有分支的长丝（24h在36°条件下）
四、Actinomyces israelii
Actinomyces israelii is a species of Gram-positive, rod-shaped bacteria within the Actinomyces.Known to live commensally on and within humans, A.israelii is an opportunistic pathogen and a cause of actinomycosis.Many physiologically diverse strains of the species are known to exist, though all are strict anaerobes.Actinomycosis is most frequently caused by A.israelii.It is a normal colonizer of the vagina, colon, and mouth.Infection is established first by a breach of the mucosal barrier during various procedures（dental, gastrointestinal)， aspiration, or pathologies such as diverticulitis.The chronic phase of this disease is also known the “classic phase” because the acute, early phase is often missed by health care providers.This is characterized by slow, contiguous growth that ignores tissue planes and forms a sinus（窦）tract that can spontaneously heal and recur, leading to a densely fibrotic lesion(纤维性病变）。This lesion is often characterized as “wooden”。Sulfur granules（瘤状颗粒）form in a central purulence（脓）surrounded by neutrophils（嗜中性粒细胞）。This conglomeration of organisms is virtually diagnostic of A.israelii.来源：
Historically speaking the first written appearance of Actinomyces was made in 1877 when pathologist Otto Bollinger described their presence in cattle.Shortly after that James Israel discovered another specie of actinomyces or actinomycetes that are living in humans and in his honour these actinomyces have name actinomyces israelii.概念性解释：
Anaerobic organism represents any organism that doesn't require oxygen for its growth and in the presence of oxygen it may even die, while facultative anaerobic organism is usually a bacteria that creates adenosine triphosphate(ATP)that is one of the most used enzymes or cabalists or it can turn to the process of fermentation if it is exposed to the positive bacteria are those that according to Gram staining are dark blue or violet in colour.If a bacterium is Gram negative it will not be able to retain the violet strain of crystal.There is one difference between Actinomyces and other bacteria and that is that Actinomyces don't form endospores and they form branched networks of hyphae that looks like fungus while other bacteria are in a shape of rod and they don't make branched networks.In fungi hyphae are the main mode of vegetative growth and their collective name is mycelium.五、Actinomyces naeslundii Actinomyces naeslundii is a Gram-positive, rod-shaped bacterium found in the mouth of humans.The species has been implicated in periodontal disease, as well as various tooth cavities.In other cases, A.naeslundii is associated with good oral health.It is one of the first bacteria to occupy the oral cavity and colonize the tooth's surface.It has also been isolated from women with bacterial vaginosis.Any species of the genus Actinomyces, including A.naeslundii, cause a chronic disease called actinomycosis, which is characterized by swelling and formation of an abscess（脓肿）which may exude pus.This
can
be by
accompanied tissue fibrosis.Figure 5Histopathological changes due to en:Actinomyces naeslundii :Silver stain, brain abscess.Obtained from the CDC Public Health Image Library.六、Actinomyces radicidentis
Actinomyces radicidentis is a species in the genus of Actinomyces, first isolated from infected root canals of teeth.ITs type strain is CCUG characterized, it has since been found to be present in failed root canal treatments.Its pathogenicity has been suggested to be due to an ability to form cell aggregates, held together by embedding in an extracellular matrix in host tissues.Like other pathogenic Actinomyces, by collectively finding itself in a protected biofilm（生物膜）environment can evade elimination by host defenses, including phagocytosis.Figure 6 Scanning(a-d)and transmission electron micrographs(e-g)of A radicidentis, strain CCUG grown on Brucella blood agar exhibit coccoid shape(a)， similar to cells grown in serum-supplemented Tryptic soy broth, where fimbriae-like bundles can be seen(b)。When cells were grown in RPMI-1640 broth with serum(c, d)， they were rod-shaped with intertwining bundles of fimbriae-like cell appendices in a netlike arrangement.In thin section(e)， bundle of fimbriae can be observed emerging from cell surface;demarcated area in(e)is magnified in(f)。Further thin section(g)shows radially placed fimbriae emerging from fuzzy-coated cell surface.Bars = 1 µm.七、Actinomyces viscosus
Actinomyces
viscosus
is
a
human
and
animal pathogen/pathobiont which colonizes the mouths of most adult humans.It is Gram-negative，anaerobic，rod-shaped，and filamentous.It causes periodontal disease（牙周病）in animals, and has been isolated from human dental calculus（牙结石）and root surface caries, as well as the oral cavity hamsters and actinomycotic lesions in swine, cats, and dogs.Furthermore, it has been shown to cause endocarditis（心内膜炎）。Actinomyces viscosus is a Gram-positive，anaerobic，filamentous bacterium that is part of the human oral flora.This rod shaped filamentous bacteria occur around the teeth, gums（牙龈）and throat in healthy humans.Species of this bacterium can cause actinomycosis-a granulomatous infection with the formation of abscesses in the mouth, lungs, or the gastrointestinal actinomycosis may occur due to trauma such as a tooth extraction or bleeding gums.Abdominal actinomycosis may follow is with antibiotics.Actinomyces are soil or aquatic fungi feeding off decaying matter(saprophytes，sapro,spoiled)。They resemble fungi and form fungi-like mats(mycelia)
关于gram-staining: 染色效果：
Figure 7A Gram stain of mixed Staphylococcus aureus(S.aureus ATCC 25923, gram-positive cocci, in purple)and Escherichia coli(E.coli ATCC 11775, gram-negative bacilli, in red)， the most common Gram stain reference -positive bacteria have a thick mesh-like cell wall made of peptidoglycan(50–90% of cell envelope)， and as a result are stained Purple by crystal violet, whereas Gram-negative bacteria have a thinner layer(10% of cell envelope)， so do not retain the purple stain
and are counter-stained pink by safranin.八、Actinomyces odontolyticus Actinomyces
odontolyticus
is
an
anaerobic, facultativecapnophilic, gram-positive, nonsporulating, non–acid fast（不耐酸的），non-motile, irregularly staining bacterium.Sometimesshort or medium-sized rods resembling diphtheroids（白喉）areseen.Shorter rods resembling propionibacteria are frequentlyseen with A.odontolyticus and may be arranged inpalisades（栅栏）as well as other diphtheroidal agar, the bacteria develop as small, irregular, whitishcolonies that are smooth to slightly granular and show adark red pigment when mature(2–14 days)。This pigmentationis most obvious when the cultures are left standing inair at room temperature after primary anaerobic isolation.The organism also grows well on A and Brucella agar.Definitive identification is made by negative catalaseand oxidase tests, the reduction of nitrate（硝酸盐）to nitrite（亚硝酸盐）， filamentationof
microcolonies, and absence of growth at pH5.5.Generally, the fermentation（发酵）reactions are variable.
放线菌的插片培养是将放线菌菌种制成孢子悬液后（浓度以10—2—10—3为好），取0.2ml放在适合放线菌生长的平板培养基上，用玻璃刮铲涂布均匀，然后将灭过菌的盖玻片斜插入固体培养基中，置28—32℃下培养，3—5天后取出盖玻片放在载玻片上镜检，可见放线菌的自然生长的个体形态。