麻省理工大学课件：系统微生物学4-微生物生长(PPT)
《微生物的生长》PPT课件 (2)
• 营养物浓度很低时，才会影响生长速度；营养物浓度增高， 生长速度不受影响，而只影响最终的菌体产量；若进一步提 高营养物浓度，则生长速度和菌体产量均不受影响。
• 生长限制因子：凡处于较低浓度范围内可影响生长速率和菌 体产量的某营养物。
– 培养温度
• 温度接近最适生长温度，则指数期短。
微生物的代谢调节 代谢调节在发酵生产中的应用
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第六章 微生物的生长
•一、教学目的与要求
– 了解微生物的生长规律，掌握测定微生物生长繁殖 方法，熟悉环境因素对微生物生长的影响
•二、教学内容：
– 1、测定生长繁殖的方法 – 2、微生物的生长规律(★) – 3、影响微生物生长的主要因素(★) – 4、微生物的培养法概论 – 5、有害微生物的控制(☆)
• 特点
– ①生长速率常数为零;②细胞形态变大或增长;③细胞 内的RNA尤其是 rRNA含量增高，原生质呈嗜碱性;④ 合成代谢十分活跃，核糖体、酶类和ATP的合成加速， 易产生各种诱导酶;⑤对外界不良条件如NaCl溶液浓 度、温度和抗生素等理、化因素反应敏感 。
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一)延滞期
• 影响延滞期长短的因素
上次教学回顾
• 第三节 微生物独特合成代谢途径举例
– 自养微生物的CO2固定
– – –
生肽微聚生物糖物固的次氮生生（物代★合谢）固 固 好成物氮 氮 氧的（微 的 菌合★生 生 固成）物 化 氮在 在 在机 酶细 细 细制 避胞 胞 胞氧质 膜 膜害外中 中机的 的的制合 合合成成成
• 第四节 微生物的代谢调节与发酵生产
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麻省理工大学课件：系统微生物学4-微生物生长(笔记)
20.106J – Systems MicrobiologyLecture 4Prof. Schauer¾Reading for today: Chapter 6 – On Growth¾Problem set due today¾Today: Growth – in microorganisms it’s different from in metazoans – increase in number of organisms instead of sizeo Binary fissiono Other methods:Organisms that replicate their DNA many times over, than splitinto many parts at once¾Next week: metabolic regulationBinary Fissiono Time from bacterium to bacteria is a generationo Generation time is how long it takeso20 minutes is a rather fast generation time. 8 minutes is the world record.o We look for bacteria that can replicate fast, or that can replicate in extreme conditions.o Cell content replicates before division.Fts proteins and the “divisome”o FtsZ aligns before divisiono The most intense signal occurs at the center edges due to the 3-dimensional shapePeptidoglycan synthesiso Peptidoglycan needs to be extgended for the cell to growo The balance needs to be right, so cell integrity isn’t compromisedo Antibiotics bind to DNA binding proteins like FtsI, so that those enzymes aren’t available for the peptidoglycan synthesis, and the bacterium lyses.(Autolysins without autolysis)o The FtsZ ring leaves a scar in the cell wall, which you can see later Peptidoglycan structureo Two planes with cross-links in between. These cross-links give it its integrityo MreB allows a variety of shapes -- not just spheresExponential Growtho Because bacteria undergo binary fission, they can replicate into mind-boggling numbers very fast (exponential rate)o After two days of unregulated growth one bacterium’s offspring would weigh more than the earth (assuming a 20 minute generation time) o Make a logarithmic plot of change in numbers as a function of timeGrowth Parameterso Write out equationso There will be homework problems relating to this growtho Related growth parametersThe growth cycleo Why aren’t bacteria always doubling? What limits their growth?They exhaust their nutrients, causing the growth curve to level offBuild up of toxic waste productso The cell has to replicate everything before it dividesTherefore if you move a cell from a bad medium to a good one,there’s a lag before it begins to grow.o Stationary phase – in a batch culture, for the most part things stay the same.o Death – in bacteria, this is exponential, like growth (very important)It’s not clear what’s going on here – people have speculated.Total cell counto Demonstration: Prof. Schauer shows the class a counting chamberGrid etched on with a laserTwo raised ridges – glass coverslip fits directly over, allowing you to measure the space between the platform and the coverslip –count through a microscopeThe same concept and method is used for bacterial, blood cells,environmental samples, etc.o Problems with this method:Not very preciseHard to seeDoesn’t distinguish live cells from dead onesRequires phase contrast microscope to count unstained cellsDilute samples must be concentratedViable counto This is the more common method – dilute sample many times overo Demonstration: Prof. Schauer displays samples of test tubes with successive dilutions – each test tube is progressively less cloudy.o Then you plate the resulting tubes and wait for colonies to appearo You want to count a plate with between 30 and 300 cellsOtherwise the error becomes too higho Demonstration: Prof. Schauer displays agar plates resulting from each successive dilutiono This kind of evaluation is difficult for slow-growing bacteria – you have to leave the plate to grow for up to a month.o This method doesn’t work for bacteria that can’t make coloniesThese bacteria might be viable, but clump (you can use detergents to try to fix this problem)Some organisms don’t separate, but come in chainso Plating methodsSometimes putting the agar on top is useful, because it stops thebacteria from moving aroundTurbidity as an indirect measureo Light scattering off of organismso Depends on morphology of organisms – larger organisms scatter more lighto You can quantify organisms by measuring the light scatteringPhotometersThis is advantageous because you can still keep using the sample Chemostat cultureo Instrument called a chemostat – bioreactor of sorts – you grow bacteria in ito Open systemo Number of bacteria and rate of growth are kept constanto It enables you to control both the bacterial concentration and the doubling time.Cardinal temperatures: extremophileso Temperature as an environmental condition – controls rate and yieldo For every organism, you can determine maximum, optimum, and minimum temperatures for growtho The optimum is always closer to the maximum than it is to the minimumo Classes of organismsSome organisms can grow in up to 113o COrganisms can grow anywhere that there’s watero PsychrophilesIt’s very clear why organisms can’t grow at very hightemperatures: proteins denature, etc.However, it’s less clear why they can’t grow in low temperatures: you lose hydrogen bonding, but that’s about all that changesTrue psychrophiles, that prefer very cold temperatures, are rareThose organisms can’t handle warmer temperatures – thereforethey live only in areas where it’s cold all year round: the North andSouth Poles, glaciers.o HyperthermophilesMost of these are archaeaArchaea probably originated at very high temperatures: thermalvents, magmaThey grow in superheated, high pressure water, over 100o CThey have positive supercoiling of DNA – everything else on earth has negative-coiled DNAProblems with membrane stability – remember, archaea havedifferent membranes from us (eukaryotes can never grow above50o CThermophileso Important source of enzymes for biotechnologyDifferently colored band at Yellowstone: each colored band is adifferent thermophileExtremophiles of pH and osmolarityo They maintain their internal cell environmentThey don’t, for example, have such low pH or such high saltconcentration inside the cell as they do outsideo Accumulate inorganic ions or make organic soluteso Compatible soluteso Note: freezing is similar to dehydration: what kills cells as they freeze is the loss of H2O as it forms into crystalso Demonstration: Prof. Schauer shows the class a device for creating an anaerobic atmosphere for growtho Toxic forms of oxygen。
微生物学(PPT格式课件)第六章微生物的生长及控制
一、 温度(temperature)
微生物学(PPT格式课件)第六章微 生物的生长及控制
根据温度对微生物的影响分类
嗜冷菌 (<20oC) 嗜温菌 (20-45oC) 嗜热菌 (50-60oC) 嗜高温菌 (80-95oC) 极端高温菌(105-150oC)
应用范围
生产为主
实验室为主
分批培养与连续培养的比较
微生物学(PPT格式课件)第六章微 生物的生长及控制
连续培养的优缺点
优点
高效 自控 产品质量稳定 节约动力、人力、水和蒸汽等
缺点
菌种容易退化 容易污染杂菌 营养物的利用率低于单批培养
微生物学(PPT格式课件)第六章微 生物的生长及控制
Thermophile and Biotechnology
来自嗜热菌的酶可在高温下稳定的催化生物化学反应；
其中由Thermus aquaticus 中分离出来的 DNA 聚合酶， Taq polymerase， 已广泛应用于PCR反应；
分离自Pyrocuccus furiosus 的 pfu polymerase应用于
嗜碱微生物（basophile） 多数放线菌、硝化细菌、根瘤菌等
耐碱微生物（basotolerant microorganism） 若干链霉菌
• 嗜酸微生物（acidophile） • 多数真菌
• 耐酸微生物(acidotolerant microorganism) 乳酸杆菌、醋酸杆菌，许多肠杆菌等
微生物学(PPT格式课件)第六章微 生物的生长及控制
Ⅲ 稳定期(stationary phase)
①生长速率常数R=0，即新繁殖的细胞数与衰亡的细 胞数相等；
微生物的生长 PPT
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第一节 微生物的生长及其特性
（4）测细胞含碳量POC（particulate organic carbon） POC＝1 X mg/l 特点：快、低浓度也可测 TOC（2total organic carbon）：总有机碳 DOC（dissolved organic carbon）：溶解性有机碳
H2N C
N
+NH2 H
2Cl-
C NH2 H2N -
DNA
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第一节 微生物的生长及其特性
DTAF染色法
5-DTAF : 5-(4,6-dichlorotriazinyl) aminofluorescein
O OH
OO
Cl
N
O
NH N
N
H
Cl
OH
DNA
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第一节 微生物的生长及其特性
③计数器法: 如血球计数板法 ④比例计数法:
将已知颗粒浓度得液体与待测菌液按一定比例混合后 在显微镜下,测各自得数目。(特点:不需测量体积)
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第一节 微生物的生长及其特性
• 活细胞染色法
美蓝染色法 （酵母活细 胞计数）
活细胞：无色 死细胞：蓝色
口丫啶橙染色法 活细胞：橙色荧光 （在紫外显微镜下 观察细胞的荧光） 死细胞：绿色荧光
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第一节 微生物的生长及其特性
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第一节 微生物的生长及其特性
二、微生物生长得测定方法
直接计数法（显微镜）
计数法
间接计数法 （关注：活细胞染色法、特定细胞计
数法） 定
量
体积法
测
重量法（湿重法、干重法）
《微生物生长》PPT课件
选择培养基分离法
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1.平板 划线法
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2.稀释倒平皿法
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在不补充营养物质或移去培养物， 保持整个培养液体积不变条件下， 以时间为横坐标，以菌数为纵坐 标，根据不同培养时间时细菌数 量的变化，可以作出一条反映细 菌在整个培养期间菌数变化规律 的曲线。
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生长曲线可 分：
延滞期 lag phase
对数期 log phase
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３．薄膜过滤计数法
常用微孔薄膜过滤法测定空气和水中的 微生物数量。
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此法适用于测定量大、含菌浓度很低的流体
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4．比浊法
为测定菌悬液中细胞数的快速方法。原 理是悬液中细胞浓度与混浊度成正比， 与透光度成反比，可用分光光度计测定 光密度，对照标准曲线求出菌液浓度。
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3. 单细胞分离法
采取显微分离法从混杂群体中直接分离单个细胞进行 培养以获得纯培养 。
在显微镜下使用单孢子分离器进行机械操作，挑取单 孢子或单细胞进行培养。也可以采用极细的毛细管在 载玻片的琼脂涂层上选取单孢子并切割下来，然后移 到合适的培养基进行培养。
微生物的生长PPT课件
基 不但要调节pH值，还要选择适合pH值的缓冲。 如磷酸盐缓冲液、碳酸盐缓冲液等。
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（3）通气条件对微生物生长的影响
好氧性微生物，在培养时必须保证通 气条件良好。实验室中通常采用震荡培养 或摇瓶培养，发酵生产中多采用通入无菌 空气和搅拌等方法供氧。
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（5）水分和渗透压对微生物的影响
水是微生物必需的营养物质，但水能不能被 利用，还需看溶液中水的可给性。 水活度：指相同温度下，密闭容器中，溶液的蒸 气压比上纯水的蒸气压。
Ps Aw=
Pw 自然界中，微生物能生长的水活度范围在 0.7～0.99之间, 一般来说细菌在0.9～1.0 , 酵母 菌和霉菌在0.9～0.95之间。
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（6）辐射对微生物生长的影响
辐射是能量以电磁波的方式通过空间传递 的一种形式，它包括无线电波、红外线、可 见光、紫外线、X射线、r射线、α 射线和β 射线等。 红外线：是光合细菌的能源。 可见光：是蓝细菌、藻类的能源。 紫外线：有杀菌和诱变作用。
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紫外杀菌
杀菌能力最强的波段在265-266nm之间， 这 是核酸的最大吸收峰波段。紫外线可作用于 DNA，导致相邻的胸腺嘧啶形成二聚体，引起微 生物变异或死亡；它也可激发空气中的氧变为臭 氧，放出氧化能力很强的新生态氧产生杀菌作 用。但紫外线的穿透力差，因此只能用于空气及 物质表面的消毒。 光复活作用：经紫外线杀死的微生物在可见光作 用下，可以激活DNA修复酶，修复损伤，从而使 微生物复活的作用。有些酶也有暗修复能力。 38
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（2）氢离子浓度
即pH值。同样pH值可影响微生物的生长和 改
变微生物的代谢产物。 pH值对微生物的影响主要作用于： 影响细胞膜电荷和养料吸收 影响代谢过程中酶的活性 改变环境中养料的可给性和有害物质的毒性
麻省理工大学课件：系统微生物学（笔记）
麻省理工大学课件：系统微生物学（笔记）20.106J – Systems MicrobiologyLecture 24Prof. SchauerFinal Exam next weekThe main focus of the final exam is going to be our last eight lectures: the topics listed belowo The format will be similar to the format of the testso Open-ended questionso You need to know the concepts –you do not need to memorize specific detailso There will also probably be a couple of questions about the lectures from earlier in the course, given by Prof. DeLong Topics:o1: Growth ControlPhysical growth controlHeat and autoclavingThe kind of cell death that occurs with heatChemical growth controlOutside of the bodyStrategies of controlling microbes on surfaces, etc.AntibioticsInhibition of cell wall synthesis, ribosomesBeta-lactam antibioticsKnow why these don’t interfere with protein synthesis inour own cellsAntibiotic design requires targeting a feature that is unique to bacterial cells, and not human ones. Asking you toformulate a hypothetical new antibiotic would a be areasonable question on the test.Antibiotic resistanceKnow that the existence of antimicrobial resistancepredated our own medical use of antibiotics. Why is that?o2: Microbe-host InteractionsHealthcare-associated infections (HAI)Know about the acquisition of drug resistance by some ofthese microbes in peopleVRE, MSRAThe fear of developing a superbug that we have to drug to treatCommensal microbiota (ecology, models)You should be familiar with the concept that there aremicrobes that live in every living thing on earthKnow about the development of a climax community ofmicrobiota in the human gut as people grow up frominfants to adultsGnotobiotic animals: in the lab, people can create rabbits,mice, or pigs grown in a sterile environment so that theyhave no microbiota inside them.You might be able to make some comparisons between our endosymbionts and those of aphidso 3.4: Immunology I and IIImmune cellsBe familiar with the main components of the immunesystemKnow the main components of lymphocytesKnow what B and T cells do once they become activated,what they secreteInflammation, phagocytosisNatural immunityGetting microbes out of the injured siteAdaptive immunity (Ag, MHC, T, B)Know the way that antibodies recognize antigens, ascompared to the way that T cells can recognize themB cells bind to conformational antigensAffinity maturationo Creates a little extra diversity in a B cell responseo However, this does not happen in T cells, because itwould be catastrophic to have T cells that recognizedifferent things –you don’t want them to startattacking your own cells. They need to recognizeyour own MHCVaccines (types)Know about the general types of vaccinesYou won’t have to name specific vaccinesUnderstand the range of successful vaccines that have been usedFor example, there’s the TB vaccine, which only protectsagainst childhood TB. You can’t give a vaccine like that to immuno-suppressed people – it could kill themAnergy (tolerance)HypersensitivityType I: IGEType IV: TB test is an exampleo5: Diagnostic MicrobiologyExotoxins: A-B toxins, SAg (Super antigens)Super antigens bind to the conserved parts of the TCR and the APCo They stimulate large numbers of T cells that sharecommon variable regions of the Beta chaino Whole sale stimulation, release of large quantitiesof cytokinesSelective, differential mediaSelective media to inhibit growth of commensalsYou can also make differential media, such as adding sugars or pH sensitive dyesMAb, serologyo6: Person-to-person TransmissionTB (risk factors, pathogenesis)Many people get exposed, many people develop latent infectionsIf they become immuno-suppressed, they can develop active TBInfluenzaAntigenic shifto Large, sudden changesAntigenic drifto Small changes in the proteins compromise the ability of your system to protect you from the virus Hp Only a small proportion actually develop peptic ulcer diseaseo7: EpidemiologyTermsIncidence, prevalence, control, transmission Emerging infectious diseaseso8: Arthropod-borne and Zoonotic DiseasesPlague (epidemiology, pathogenesis)Wild rodents, transmission through fleas on a sporadic basisBe familiar with how plague affects the flea life cycle, causing it to bite more peopleBubonic, Systemic, and Pneumonic forms of plague。
2024年度《微生物学》PPT课件
命名规则
采用双名法，即属名和种名，用斜体拉丁文表示，属名在前，种名在后。例如：Escherichia coli（大肠埃希氏菌 ）。
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微生物的鉴定方法与步骤
鉴定方法
表型鉴定（形态学、生理生化特征）、遗传学鉴定（基因型、DNA序列分析）、血清学鉴定（抗原抗 体反应）等。
鉴定步骤
采集样品、分离纯化、形态观察、生理生化试验、血清学试验、分子生物学试验等。
呼吸作用类型
分为好氧呼吸、厌氧呼吸和兼性厌氧 呼吸，不同类型的微生物在不同环境 条件下进行不同的呼吸作用。
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微生物的物质代谢与合成作用
01
碳源利用与分解代 谢
微生物利用不同碳源进行分解代 谢，包括单糖、多糖、脂肪和蛋 白质等。
02
氮源利用与合成代 谢
微生物利用不同氮源进行合成代 谢，合成自身所需的氨基酸、核 苷酸等含氮物质。
营养类型
根据微生物对营养需求的不同，可分为自养型、 异养型和兼性营养型。
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微生物的生长曲线与测定方法
生长曲线
描述微生物在适宜条件下 生长繁殖的四个阶段，即 延迟期、对数期、稳定期 和衰亡期。
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测定方法
包括直接计数法（如显微 镜计数法、平板菌落计数 法）和间接测定法（如比 浊法、生理指标法等）。
01
球菌、杆菌、螺旋菌
细菌的结构
02
细胞壁、细胞膜、细胞质、核质
特殊结构
03
荚膜、鞭毛、菌毛、芽孢
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真核微生物的形态与结构
真菌的形态
酵母菌、霉菌、大型真菌
真菌的结构
菌丝、孢子、细胞壁、细胞膜、细胞质、细胞核
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Growth parameters
• Number of cells (N) after n generations beginning with N0 cells
• N = 2n N0
Graph of cell growth over time removed due to copyright restrictions. See Figure 6-7b in Madigan, Michael, and John Martinko. Brock Biology of Microorganisms.11th ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2006. ISBN: 0131443291.
• If you know n and t, you can calculate g, k, and v for organisms growing under different conditions
The growth cycle
• Lag phase • Exponential phase • Stationary phase
Graph showing the lag, exponential, stationary, and death phases of cell growth removed due to copyright restrictions. See Figure 6-8 in Madigan, Michael, and John Martinko. Brock Biology of Microorganisms. 11th ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2006. ISBN: 0131443291.
log N = n log2 + Nhomakorabeaog N0
n = log N - log N0 0.301
Related growth parameters
• Slope = 0.301 n/t = the specific growth rate (k)
• Division rate (v) = 1/g • Slope = v/3.3
Exponential growth
• From semi-log plot of cell density s a function of time can determine generation time (g) from time (t) and number of generations (n)
Diagram showing the process of binary fission removed due to copyright restrictions. See Figure 6-1 in Madigan, Michael, and John Martinko. Brock Biology of Microorganisms. 11th ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2006. ISBN: 0131443291
• g = t/n
Graph of cell growth over time removed due to copyright restrictions. See Figure 6-6b in Madigan, Michael, and John Martinko. Brock Biology of Microorganisms. 11th ed. Upper Saddle River, NJ: PearsonPrentice Hall, 2006. ISBN: 0131443291.
Peptidoglycan
G MG MG MG MG MG MG
G M G M GM G Cytopasmic membrane Outside
M G MG MG
Growing point of cell wall
PP
Inside Pentapeptide
MG PP
Bactoprenol
Figure by MIT OCW.
Binary fission
• In prokaryotes, growth = increase in number of cells
• Generation time is the time required for 1 bacterium to become 2 bacteria
• E. coli generation time is ~ 20 min
Fts proteins and the “divisome”
Image removed due to copyright restrictions. See Figure 6-2b in Madigan, Michael, and John Martinko. Brock Biology of Microorganisms. 11th ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2006. ISBN: 0131443291.
Peptidoglycan synthesis
• New cell wall is synthesized from the FtsZ ring
• Need to extend existing chains without compromising integrity
• Autolysins without autolysis
Images removed due to copyright restriction See Figure 6-3 in Madigan, Michael, and John Martinko. Brock Biology of Microorganisms. 11th ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2006. ISBN: 0131443291.