单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,第2章 原核生物的主要类群,原核生物简要介绍,1 原核生物的生理多样性,2 原核生物的分类,In Bergeys Manual the groups of prokaryotes are formed based on easily-observed characteristics such as Gram stain,morphology(rods,cocci,etc),and on distinguishing physiological features(e.g.anoxygenic photosynthesis,methanogenesis，etc.).Nowadays,of course,the politically correct way to group organisms,especially prokaryotes,is on a genetic basis,i.e.,by comparison of the nucleotide sequences of the small subunit ribosomal RNA that is contained in all cellular organisms.,一、古细菌,1 ssrRNA 分类：嗜泉古菌界、广域古菌界、初生古菌界,2 生理性状分类：产甲烷菌、极端嗜盐菌、极端嗜热菌,（一）产甲烷菌,1 特殊的代谢方式,2,Methanococcus jannischii,（詹氏产甲烷菌）,（二）极端嗜盐菌,1 细菌紫膜质（一种集光色素）利用其把光能转化为ATP,2,Halobacterium salinarium,（嗜盐盐杆菌）,（三）极端嗜热菌,1 高温低pH环境（一般需要S元素）,2,Sulfolobus,（,硫化叶菌是第一个被发现的极端嗜热菌）,3,Sulfolobus acidocaldarius,(嗜酸热硫化叶菌）,图示L-R：横切面的电子显微照片；细胞黏附在硫晶体上的荧光显微照片,二、Bacteria（真细菌）,Phylogenetic tree of Bacteria,Photosynthetic purple and green bacteria,1 细菌光合作用（不产生氧气、利用叶绿素,a、只有一种光合系统、细菌光合作用的电子受体不是水而是比水氧化还原电位低的物质如氢气等）,2 紫细菌和硫细菌形态多样,Purple sulfer bacteria,Green sulfer bacteria,Cyanobacteria（,蓝细菌,）,1 蓝细菌的形态,蓝细菌大多为球状或丝状，单个营养细胞具有双层细胞壁，壁外有称为鞘的粘质层，细胞膜下有类囊体，藻胆蛋白就附在类囊体上。
蓝细菌细胞内有气泡，,气泡,可以保持细胞浮在上层水上，丝状蓝细菌内产生特殊异形孢来,固定氮气,2 蓝细菌的行动,蓝细菌以滑行或者旋转进行活动3 蓝细菌的生殖,球状蓝细菌以二分分裂生殖，子细胞再分裂形成一个群落，丝状蓝细菌通过裂殖为断殖体进行繁殖4 蓝细菌的生态,蓝细菌是光合自养细菌，在地球上分布广阔，自热带直到两极都有，普遍生长在淡水、海水和土壤内5 固氮蓝细菌,大多蓝细菌都可以固氮，主要的固氮蓝细菌大都属于念珠蓝细菌科和伪歧蓝细菌科常见的蓝细菌,L-R：丝状的颤蓝细菌，念珠蓝细菌，鱼腥蓝细菌（异形孢）,Spirochetes（,螺旋体）,螺旋体的形态和运动,螺旋体 菌体细长螺旋状，以中轴丝或内鞭毛运动,图示L-R：,（,1,）,内膜和外鞘的内生鞭毛,（,2,）,Borrelia,burgdorferi,（,布氏疏螺旋体）,（,3,）,Treponema,pallidum,(,梅毒病菌）,Spirilla,（螺旋菌）,1.螺旋菌的基本介绍,螺,旋,菌是一类革兰氏阴性的好气异养菌，卷曲或螺旋状，代谢方式是发酵而不是呼吸，有坚硬的细胞壁以极生鞭毛运动,2.已发现的两种人类致病菌,Cymylobacter,jejuni,(,引发细菌性腹泻）,Helicobacter,pylorti,(,引发消化性溃疡）,Myxobacteria（,粘细菌）,1.粘细菌的基本介绍,粘菌是一类滑行细菌其原生质聚集在一起形成多细胞的子实体，子实体发育产生孢子进行繁殖。
有的粘菌的粘孢子在子实体顶端还形成称为孢囊的二级结构2.,Stigmatella aurantiaca,（橙色标桩粘细菌）,Lithotrophy（,无机营养菌,）,1.Lithotrophy,a type of metabolism that requires inorganic compounds as sources of energy2.The most important lithotrophic bacteria are the nitrifying bacteria（硝化细菌）.,3.Most lithotrophic bacteria are autotrophs（自养生物）,and,in some cases,they may play an important role in primary production of organic material in nature.,Pseudomonads and their relatives,1.假单胞菌是一类革兰氏阴性细菌有着严格的呼吸代谢模式2.许多假单胞菌和大肠菌在形态与生境上类似，但也有一些区别，假单孢菌以极生鞭毛运动，大肠菌以缘毛运动，假单胞菌不发酵糖，大肠菌发酵葡萄糖等。
3.L-R 电子显微照片，负染色；扫描电镜照片；革兰氏 染色,4.A few relatives of the pseudomonads are pathogens of animals,i.e.,the agents of whooping cough(百日咳),Bordetella pertussis,Legionaires pneumonia,Legionella pneumophilia,gonorrhea(淋病),Neisseria gonorrhoeae,and bacterial meningitis(脑膜炎),Neisseria meningitidis,.,Entertics（,肠细菌,）,1.Enteric bacteria are Gram-negative rods with facultative anaerobic metabolism（兼性厌氧代谢）that live in the intestinal tracts of animals.,2.,E.coli,is the most studied of all organisms in biology because of its occurrence,and the ease and speed of,growing the bacteria in the laboratory.,Vibrios（,弧菌,）,1.Vibrios(which have a curved rod morphology or comma shape)are very common bacteria in aquatic（水生）environments.,2.The genus,Vibrio,contains an important pathogen of humans,Vibrio cholerae,（霍乱弧菌）,the cause of Asiatic cholera（亚洲霍乱）.,弧菌菌体只有一个弯曲，呈弧状或逗点状。
弧菌属,(,Vibrio,),广泛分布于自然界，尤以水中为多，有,100,多种主要致病菌为霍乱弧菌和副溶血弧菌（致病性嗜盐菌）前者引起霍乱；后者引起食物中毒Nitrogen-fixing organisms,1.Members are unified only on the basis of their metabolic ability to“fix”nitrogen.,2.,典型示例是根瘤菌刺激豆科植物生成根瘤并共生固氮3.Cyanobacteria（蓝细菌，旧称蓝绿藻或蓝藻）are likewise very important in nitrogen fixation.Cyanobacteria provide fixed nitrogen,in addition to fixed carbon,for their symbiotic partners which make up lichens（地衣）.,4.Besides nitrogen fixation,bacteria play other essential roles in the processes of the nitrogen,cycle.,The pyogenic cocci（,脓球菌,）,The pyogenic cocci are spherical bacteria which cause various suppurative(pus-producing)infections in animals.,Included are the Gram-positive cocci,Staphylococcus aureus,Streptococcus pyogenes,and,Streptococcus pneumoniae,and the Gram-negative cocci,Neisseria gonorrhoeae,and,N.meningitidis,.,Lactic acid bacteria（,乳酸菌,）,Lactic acid bacteria are Gram-positive,nonsporeforming rods and cocci which produce lactic acid as a sole or major end product of fermentation.,They are important in the food industry as fermentation organisms in the production of cheese,yogurt（酸奶）,buttermilk（奶油）,sour cream,pickles（泡菜）,sauerkraut（酸菜）,sausage（香肠）and other foods.,Important genera are,Streptococcus,（链球菌属）and,Lactobacillus（,乳杆菌属）,.,Some species are normal flora（菌群）of the human body(found in the oral cavity,GI tract and vagina);some streptococci are pathogens of humans(see pyogenic cocci above).Certain oral lactic acid bacteria are responsible for the formation of dental plaque and the initiation of dental caries(cavities).,Endospore-forming bacteria,1.Endospore-forming bacteria produce a unique resting cell called an endospore.They are Gram-positive and usually rod-shaped.The two important genera are,Bacillus,（芽孢杆菌属）and,Clostri。