6 微生物的生长及其控制(英文教案简版)

3、Isolation
• Make a pure culture that contains only a single species of microbe. • Separate colonies（菌落） on solid media; • Further isolation --- subculturing（移种、接种）.
over the depression creating a precise volume
between 0.02-0.1uL.
血球计数板
• 1个大方格分为25个中方格，每个中方格分为16个小方格
• 1个大方格分为16个中方格，每个中方格分为25个小方格
• 计数室容积 = 1×1×0.1mm3
• 1mL菌液中的总菌数 =
• Small cells are difficult to count;
• Need high cell concentration, 106cells/mL.
3、Viable counts（活菌计数法）
• Using the spread-plate technique（涂布法）or
pour-plate method（倾注法）;
1、Turbidity Count（比浊法）
• Using a nephelometer or a spectrophotometer to
estimate cell numbers in liquid culture ; • In general, the greater the turbidity, the larger the population size; • The absorbance （吸光度）or optical density ( OD ) （光密度）is influenced by the size, shape and nature of the cells.
2、Incubation
• A temperature—controlled chamber or incubator; • Setting the optimum temperature and gas content; • Incubation produces a culture---the visible growth of the microbe in the medium.
Chapter 8
Microbial Growth and Growth Control
Chapter Outline
• Methods of Culturing Microorganisms
• Measurement of Growth
• Population Growth • Continuous Culture: the Chemostat • Effect of Environment on Growth • Physical and Chemical Control of Microbes
• The length of this time depends on the history of the culture and growth conditions.
If this comes from a fresh culture in the same medium, the lag phase will be short; If the inoculum is old or the medium has been changed ( especially moving bacteria from a rich medium to a poor one )，the lag phase will be longer.
A ×25×104×稀释倍数 5 A 5
1mL菌液中的总菌数 =
×16×104×稀释倍数
Peteroff-Hauser counting chamber Hawksley counting chamber
计 菌 器
Limitations of microscopic count
• Dead cells and living cells are not distinguished;
• To make a 10-fold (10−1) dilution;
• Count colonies only on plates that have between 30
and 300 colonies;
• cfu/mL ：colony-forming unit/mL.
Sources of Error in Plate Counting
分区划线（适用于浓度较大的样品） 连续划线（适用于浓度较小的样品）
（2）Spread Plate
（涂布法）
• To make a 10-fold (10−1) dilution;
（3）Pour plate
（倾注法）
• To make a 10-fold (10−1) dilution; • One difference between this and the spread plate method is that in this technique some of the colonies will develop in the medium itself and not
• Lag phase（延滞期、调整期、适应期） • Exponential phase（指数期、对数期） • Stationary phase（稳定期、平衡期） • Death phase（衰亡期）
1、Lag Phase
• Bacteria are first introduced into a new enviroment or fresh media;
Other methods for monitoring growth
• Wet and dry weight of cells;
• Biochemical analysis of cellular components such
as protein, nucleic acids or ATP;
• Change of conductivity and changes in electrical
• Inoculum size（接种量）; • Suitability of medium;
• Incubation conditions (medium, temperature, time);
• Length of incubation; • Size of colonies; • Single colony may arise from more than one cell clump.
（1）Streak Plate
（平板划线分离法）
• Gradually thins out the sample; • Separates the cells spatially over several sections of the plate. • Because of its effectiveness and economy of materials, the streak plate is the method of choice for most application.
impedance.
三、Population Growth
• Batch culture（分批培养） Inoculating 接种
Incubating
Sampling
培养
取样
Counting
计数
• Population growth curve
A graph of the log10 viable cell numbers against
under specific growth conditions if an accurate
estimation of cell numbers is required.
2、Total Counts （全菌计数法）
• Direct microsopic counting method
• Using specialist counting chambers（血球计数板、 计菌器） under the microscope; • Counting chambers: consisting of a grid of known area in a glass slide. A rigid coverslip is placed
5cal tests;
• Immunologic tests; • Genetic analysis.
二、Measurement of Growth
• Microbial growth
Increase in cellular constituents; Increase in a microorganism’s size, population number, or both. • Measurement Total cell number; Population of viable microorganisms; Cell mass.
Application of turbidity count
• For monitoring microbial growth it is often
sufficient to measure the changes in turbidity or absorbance of the culture with time of incubation; • A standard curve relating turbidity to cell numbers is required for each individual species
just on the surface.
4、Inspection
• Growth characteristics ：color, texture, size，etc ;
• Microscopic details ： cell shape, size, motility, etc;
• Staining techniques ：microscopic morphology.
time；
Used to plot bacterial growth owing to the large
numbers of cells produced；
To reveal the exponential nature of bacterial
growth.
Stages in the Normal Growth Curve
• No growth occurs;
• Cells are very active metabolically;
• Cells changes very little; • Microbes are sensitive to adverse conditions antibiotics anti-microbial agents
Limitations of turbidity count
• Indirect counting
Dead cells and living cells are not distinguished
Particles in culture disturb measurement
• Not good at high concentrations
一、Methods of Culturing Microorganisms
• Five I’s
Inoculation（接种） Incubation（培养） Isolation（分离） Inspection（观察） Identification（鉴定）
1、Inoculation
血球计数板?1个大方格分为25个中方格每个中方格分为16个小方格?1个大方格分为16个中方格每个中方格分为25个小方格?计数室容积1101mm3?1ml菌液中的总菌数25104稀释倍数1ml菌液中的总菌数16104稀释倍数5a5apeteroffhausercountingchamberhawksleycountingchamber计菌器limitationsofmicroscopiccount?deadcellsandlivingcellsarenotdistinguished
• Placed into a container of sterile medium; • Using a sterile tool to spread the sample on the surface of a solid medium or to introduce the sample into a flask or tube.