1、 Section 2 Bacterial Multiplication and Metabolism Nutrient Requirements carbonnitrogeninorganic saltwatergrowth factorBacterial requirements for growth nutrients optimal pH optimal temperature oxygen (or absence) osmotic pressure pH grow best at neutral pH: 7.07.6 Some can survive/grow - acid pH 3

2、- alkali pH 9Growth temperature psychrophile: -530 mesophile: 1045 human body temperature: 37 pathogens opportunists thermophile: 2595 Growth atmosphere strict (obligate) aerobe microaerophilic bacterium 56% facultative anaerobe strict (obligate) anaerobe Reason that obligate anaerobes cant grow in

3、oxygen condition: (1) Lack of cytochrome and cytochromase Eh 300mv/120mv (2) Lack of superoxide dismutase (SOD) , catalase , peroxidase superoxide dismutase O2-+2H+ H2O2 catalase H2O2 H2O peroxidase H2O2 H2O osmotic pressure halophilic bacterium: 3% Nacl bacterial L-form: 3% -5% NaclMode and speed o

4、f Bacterial reproduction binary fission generation time: time for bacterial mass to double 2030min Growth in a broth culture -The Growth curve (1)lag phase ： adaptation (2) logarithmic phase： most rapid reproduction (3) stationary phase： rate of reproduction=rate of dead (4) decline phase： rate of d

5、ead rate of reproduction.declineBacterial Metabolism Metabolic products 1. Catabolic products and biochemical reaction VP test methyl red test citrate utilization test indole test 2. Anabolic products and clinical significance 1) pyrogen polysaccharide of G- cell wall(LPS) anti-high temperature 121 , 30min Fluid infusion reaction 2) toxin and invasive enzymes exotoxin endotoxin enzyme 3) pigment water-soluble P. aerogenosa -green fat -soluble S. aureus golden 4) antibiotics killing or inhibiting substances produced by some kinds of microorganisms Actinomycete 5) bacteriocin prot