复旦大学：《医学微生物学 Medical Microbiology（MBBS）》课程讲义_理论课_Lecture2-bacterial growth and culture

Growth Culture of bacteria Chapter 4, 5

Growth & Culture of Bacteria Chapter 4, 5

Key Words Obligate aerobe Obligate anaerobe Generation time Facultative anaerobe Microaerophilic Growth curve Mesophile Thermophile Psychrophile

Key Words Obligate aerobe Obligate anaerobe Facultative anaerobe Microaerophilic Mesophile Thermophile Psychrophile Generation time Growth curve 2

Growth of bacteria Bacterial Multiplication- Binary Division 1 to 2 to 4 to 8 to n Cell wal Cell membrane Log Growth Elongated nucleoid Nucleoid divides: cell wall and membrane Number begin to form transverse septum 20 Transverse septum becomes complete Daughter cells Chapter 4 Generations separate

Growth of bacteria Bacterial Multiplication - Binary Division 1 to 2 to 4 to 8 to N Log Growth ? Chapter 4

Stationary phase Death or Log or logarithmic exponential decline phase a growth phase Lag hase Chapter 4 Fig. 4-2 Time Source: Brooks GF, Carroll KC, Butel. Phase Medical Microbiology, 26th Edition: w Growth rate Lag Zero Copyright o The McGraw-Hill Compal Exponential Constant Maximum stationary zero Decline Negative(death)

Phase Growth Rate Lag Zero Exponential Constant Maximum stationary Zero Decline Negative (death) Chapter 4 Fig. 4-2

Phases of bacteria growth(in vitro) Growth curve Lag Adapt to nutrients Log Active growth Stationary Death Growth rate Death Nutrients consumed pH too low(why? Optimize curves in production

Phases of bacteria growth (in vitro) Growth curve • Lag – Adapt to nutrients • Log – Active growth • Stationary – Death = Growth rate • Death – Nutrients consumed – pH too low (why?) • Optimize curves in production

Note the drop-off as you get closer to the Optimum! Enzymes and reactions occurring at maximal possible rate Enzymes and reactions Optimum occurring at increasingly rapid rates Minimum Maximum Temperature Membrane gelling; transport Protein denaturation; collapse processes so slow that of the cytoplasmic membrane; growth cannot occur thermal lysis

Note the drop-off as you get closer to the Optimum!

Bacterial Growth Curve Growth phases E0E Lag Exponential s Stationary Death 9.0 110 Turbidity 10.75 8.0 Viable count (optical density) 050 7.0 8 025 ⊙6.0 50 0.1 Time Is it the same as in human body Why?

Is it the same as in human body ? Why? Bacterial Growth Curve

Nutritional Factors Carbon Source Hetero- or auto- Organic compounds or cO2 Nitrogen Source NO3==> NO2==>NH3 to Amino Acids==> Proteins Sulfur ° Phosphorus Trace Elements Fe, some required for growth or virulent Host sideophores bind Fe

Nutritional Factors • Carbon Source – Hetero- or Auto- – Organic compounds or CO2 • Nitrogen Source – NO3- ==> NO2 ==> NH3 to Amino Acids ==> Proteins • Sulfur • Phosphorus • Trace Elements – Fe, some required for growth or virulent – Host sideophores bind Fe

Cultivation of bacteria All pathogenic bacteria are heterotrophic -obtain energy by oxidizing organic molecules (Carbohydrates, lipids and protein) Metabolism-yield aTP as an energy source Aerobic respiration, 1 glucose produce 38 ATP enzymes Anaerobic respiration, 1 glucose produce 2 ATP (fermentation)-enzymes Requirement for oxygen in respiration - obligate Chapter 5 -facultative p657

All pathogenic bacteria are heterotrophic -obtain energy by oxidizing organic molecules (Carbohydrates, lipids and protein) Metabolism- yield ATP as an energy source -Aerobic respiration, 1 glucose produce 38 ATP - enzymes -Anaerobic respiration, 1 glucose produce 2 ATP (fermentation) -enzymes Requirement for oxygen in respiration -obligate -facultative Chapter 5 p.657 Cultivation of bacteria

Requirements for bacterial growth ◆ Nutrients H2O, C-source(organic), N-source(organic) Inorganic salts Growth factors ◆ Temperature Pathogenic bacteria pl culture condition? ◆Gas Incubator->Temperature, gas Culture medium ->Nutrients, pH

Requirements for bacterial growth  Nutrients H2O, C-source(organic), N-source (organic) Inorganic salts Growth factors Temperature  pH  Gas Incubator → Temperature, gas Culture medium → Nutrients, pH Pathogenic bacteria culture condition?