北京大学：《微生物学》课程PPT教学课件（英文版）Chapter 4 Metabolism, Biosynthesis and Nutrition

Chapter 4 Metabolism, PA Biosynthesis and Nutrition AA Microbial Nutrition Laboratory culture of Microorganisms Sterilization, Aseptic Technique, and Pure Cultures

Chapter 4 Metabolism, Biosynthesis and Nutrition • Microbial Nutrition • Laboratory Culture of Microorganisms • Sterilization, Aseptic Technique, and Pure Cultures

Microbial Nutrition K WISALNHGIANNH CAY Nutrients: substances in the environment used by organisms for cata bolism and anabolism. Macronutrients: required in large amounts including: C, N,P,S,O,H,K,Mg, Ca, Na, Fe. Micronutrients: required in small amounts including: Co, Zn, Mo, Cu, Mn, Ni, W, Se

Microbial Nutrition Nutrients: Substances in the environment used by organisms for catabolism and anabolism. Macronutrients: required in large amounts, including: C, N, P, S, O, H, K, Mg, Ca, Na, Fe. Micronutrients: required in small amounts, including: Co, Zn, Mo, Cu, Mn, Ni, W, Se

Laboratory Culture of Microorganisms 1.5%o Agar C: Organic-Defined media glucose, sucrose, acetate pyruvate, malate, fatty acids, alkanes et al. Complex media yeast extract, beef extract, peptone, many other complex digests Inorganic-CO2, HCO3- "g。 N: Organic-Amino acids nitrogenous base Inorganic-NH4CI, (NH4)2SO4 KNO3 N2 P: KH2PO4 Na2HPO4 S: NaSO4 H2S K: KCL K2HPO4 Mg: MeCl2 MgSo4

Laboratory Culture of Microorganisms • C:Organic-Defined media: glucose, sucrose, acetate, pyruvate, malate, fatty acids, alkanes et al. Complex media: yeast extract, beef extract, peptone, many other complex digests. Inorganic-CO2 , HCO3 - • N: Organic-Amino acids, nitrogenous bases; Inorganic-NH4Cl, (NH4)2SO4, KNO3, N2. • P: KH2PO4, Na2HPO4. • S: NaSO4, H2S. • K: KCl, K2HPO4 • Mg: MgCl2, MgSO4 1.5% Agar

Petri Disk Cultivation of a Pure Strain

Petri Disk Cultivation of a Pure Strain

Microorganisn s grow and Microbial replicate only when all of their nutritional and environmental Growth needs are met. Thus. a micro bial medium must contain all re quisite w Conditions nutrients and be incubated at the appropniate nH, temperature 1. Macronutrients and atmos phere (ie. the presence or absence of oxygen). 2. Micronutrients A medium can be liquid or solid, 3. Growth factors defined or complex, selective or differential Liquid media are 4. Environmental factors usually dear solutions of dissolved nutrients, composed or a temperature either known compounds (n b pH defined media)or mixtures of extracts of beef, yeast, or casein c Oxygen: Aerobes (n complex me dia). solid media Anaerobes are made by adding gelling Facultative aerobes agents, usually agar, to liquid media d osmotic pressure

Microbial Growth Conditions 1. Macronutrients 2. Micronutrients 3. Growth factors 4. Environmental factors: a. temperature b. pH c. Oxygen: Aerobes, Anaerobes, Facultative aerobes d. osmotic pressure

The Streak Plate Techniques to obtain a pure clone Bunsen burner Petri dish Higher concentration of cells Lower concentration of cells Second set of streaks Fourth set of streaks

The Streak Plate Technique: to obtain a pure clone

N Chapter 9 sA2 Growth and Its Controx In Microbiology, growth is defined as an increase in the number of cells Control of microbial growth -Physical ways -Chemical ways

Chapter 9 Growth and Its Control • In Microbiology, growth is defined as an increase in the number of cells. • Control of Microbial Growth: –Physical ways, –Chemical ways

Microbial growth and death can refer to either micro bial populations or individual cells. Cell Growth Unlike changes in individual cells, changes in population size obey mathematical laws that can Growth rate is the change in cell precise y I predict growth rate number or mass per unit time knowing how these laws apply to the time interval for the a particular culture enables us to formation of two cells from one is predict what the size of a called generation time population will be after, say, a The number of cells doubles certain period of exposure to a during each unit time period, is perature usual,no high tel referred to as exponentialgrowth such predictions can be made about individual cell growth Relationship between the number of cells present in a culture initially (no) and the number What becomes abundantly dear present after a period of after studying microbial growth is exponential growth (N) that prokaryotes are the fastest N=N 2 or n=(log(N)-log(No)/og2 growing and most resistant organisms in existence n-the number of generation

Cell Growth Growth rate is the change in cell number or mass per unit time. The time interval for the formation of two cells from one is called generation time. The number of cells doubles during each unit time period, is referred to as exponential growth. Relationship between the number of cells present in a culture initially (N0 ) and the number present after a period of exponential growth (N): N=N02 n or n=(log(N)-log(N0 ))/log2 n=the number of generation

Binary fission is most common, followed by budding. Multiple fission is fairly uncommon. In binary fission, cells enlarge 3 types of evenly and divide in two. Where cell there is a wall layer, each daughter cell inherits half of the division: old wall material and half of the a Binary newly synthesized wall. In budding, cell growth is localized Fission and at division one cell inherits b Budding, mainly old wall material: the other c Multiple inhents mainly new wall material In muliple esSion, the cell Fission enlarges to several times its oniginal size, then divides into multiple daughter cells

3 types of cell division: a.Binary Fission, b. Budding, c. Multiple Fission

Binary Fission(分 Binary Fission r Ney wall old fall

Binary Fission (二分裂)