Transcript Chapter2 Bacterial Physiology

Chapter2
Bacterial Physiology
Xin Gang
Department of microbiology and immunology
Shantou University medical college
outline
I. Physical and Chemical Properties
II. Growth and Proliferation
III.Metabolism
IV. Cultivation Method
V. Classification and Nomenclature
I Physical and Chemical Properties
i. Chemical composition
Water, inorganic salts, proteins, carbohydrates,
lipids, nucleic acids
Macronutrients(macroelements)
Carbon, oxygen, hydrogen, nitrogen, sulfur,
phosphorus and other metal ions (potassium,
calcium, magnesium and iron)
The first six(C, O, H, N, S, and P) are
components of carbohydrates, lipids,
proteins, and nucleic acids.
Micronutrients(trace elements)
ii. Physical properties
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Optical property
Surface area
Charged phenomena
Semi-permeability
Osmotic pressure
II Growth and Proliferation
i. Bacterial requirements for growth
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Nutrients
pH
Temperature
Oxygen
Osmotic pressure
(Optimal environmental condition)
Nutrients
Nutrient Requirements
– Carbon sources
– Nitrogen sources
– Inorganic salts and trace elements
– Growth factors
– Water
Nutritional types of bacteria
• Autotroph
reduced inorganic molecules
• Heterotroph
organic molecules
– saprophyte
– parasite
Uptake of nutrients by bacteria
o Passive diffusion
simple diffusion
Facilitated diffusion
o Active transport
pH
• Many bacteria grow best at neutral pH.
(pH 7.2-7.6)
• Some specialized bacteria can survive
and even grow in acid or alkaline
conditions.
– T.B.
– V. cholerae
pH 6.5-6.8
pH 8.4-9.2
Temperature
Temperature and Growth
Optimal T
Psychrophiles
10-20 C
Mesophiles
20-40 C
Thermophiles
56-60 C
Heat-shock proteins, Hsp
Temperature ranges for microbial growth
Oxygen Requirements
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Obligate aerobes
Must grow in the presence of air
They can not carry out fermentation
Microaerophilic bacterium
Grow well in low concentrations of oxygen
Killed by higher concentrations of oxygen
Facultative anaerobe
Perform both fermentation and aerobic
respiration
Can survive in the presence of oxygen
Obligate anaerobe
• Obligate anaerobes
– Do not carry out oxidative phosphorylation
– Killed by air
– Lack certain enzymes
cytochrome and cytochrome oxidace
superoxide dismutase (SOD)
O2- + 2H+ to H2O2
catalase
2H2O2 to 2H2O + O2
peroxidase
H2O2 to H2O using NAD to NADH
ii. Growth and multiplication
mode: Binary fission
Generation time:
the time required for bacterial mass to double.
20-30min, T.B. 18-20h
The growth curve
Phases of Microbial Death Curve
Section
of
curve
A
Lag
Phase
Growth rate
Zero
B
Log
Constant
C
stationary
Decreasing
D
Death
Negative(death)
CO2
Osmotic pressure
III Metabolism
i. Energy metabolism of bacteria
– Catabolism
– anabolism
– Respiration
– Fermentation
ii. Metabolic products of bacteria
1. Catabolism and biochemical reaction
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Sugar fermentation
• IMViC
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Indole
Methyl red
VP
Citrate utilization
H2S
Urease
2. Anabolic products of bacteria
– Pyrogen
– Toxin and invasive enzyme
(endotoxin, exotoxin)
– Pigment
– Antibiotics
– Bacteriocin
– Vitamins
IV Cultivation Method
i. Environmental factors affecting growth
Nutrients; pH; Temperature; Aeration ; Ionic
strength; Osmotic pressure
Basic medium
0.3% 牛肉膏
1% 蛋白胨
0.5% NaCl
Liquid medium
Solid medium
(0.3-0.5% agar) Semi-solid medium
(1-2% agar)
ii. Growth of bacteria in culture
medium
i. Liquid medium or Broth
1) Homogeneous turbidity
2) Surface
3) Bottom
ii. Solid agar medium
Colony and mossy
1) Smooth colony
2) Rough colony
3) Mucoid colony
iii. Semi-solid agar medium
iii. Types of Culture medium
basic medium
nutrient medium
selective medium
differential medium
anaerobic medium
iv. Usage of bacterial culture
i. Diagnosis, prevention and treatment
of infection diseases
ii. Characterization of bacteria
iii. Preparation of vaccines, toxoids and
other biologic prducts
iv. Application in industry and
agriculture
v. Uses for genetic engineering
V Classification and nomenclature
Taxonomic ranks
Formal rank
Kingdom
Division
Class
Order
Family
Genus
Species
Example
Prokaryotae
Gracillicutes
Scotobacteria
Eubacteriales
Enterobacteriaceae
Escherichia
Coli
Family：a group of related genera.
Genus：group of related species.
Species: a group of related strains.
Type: sets of strain within a species
– serotype
– Phage-type
– biotype
– genotype
Strain: one line or a single isolate of a
particular species.
Bionomial Nomenclature:
genus+species
Genus Species
种名
S.
aureus
金黄色 葡萄球菌
N.
meningitides
脑膜炎
奈瑟菌
E.
coli
大肠
埃希菌
属名
Chapter3
Disinfection and sterilization
outline
Definition
Physical methods
Chemical methods
I Definition
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Disinfection
Sterilization
Antisepsis
Asepsis, asepsis technique
i. Disinfection
– killing, or removal of
microorganisms that may cause
disease.
– primary goal is to destroy
potential pathogens.
ii. Sterilization
– all living cells, viable spores,
viruses, and viroids are either
destroyed or removed from an
object or habitat.
– totally free of viable
microorganisms, spores, and
other infectious agents.
iii.Antisepsis
– prevention of sepsis and is
accomplished with antiseptics.
iv. Asepsis
– without living microorganisms
Methods for control of
microorganisms
Physical methods
Heat
Hot-air sterilizer
Autoclaving
Radiation
Filtration
Ultrasound
Dryness
Low temperature
Chemical agents
II physical methods
i. Heat
1. Dry heat
Incineration
Direct flames
Hot-air sterilizer
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160-170C for 2 hours----spores
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Glass petri dishes and pipettes
Infrared
microwave
2. Moist heat
Pasteuriztion
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63C for 30min
Flash pasteuriztion - 72C for 15s
Ultrahigh-temperature(UHT)
sterilization-140 to 150C for 1 to 3s
Boiling
Free-flowing steam disinfection
Autoclaving
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15 pounds(1.05kg/cm2), 121C for 1520min
ii. Radiation
Ultraviolet, UV
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250-260nm
Quite lethal but does not penetrate glass, dirt
films, water, and other substances very
effectively.
To sterilize the air and any exposed surfaces
Can burn the skin and damage eyes
Ionizing radiation
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An excellent sterilizing agent and penetrates
deep into objects
Cobalt 60 source
iii. Filtration
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Rather than directly destroying
contaminating microorganisms, the filter
simply removes them.
Membrane filter
iv. Ultrasound
v. Dryness
vi. Low temperatures
III The Use of Chemical
Agents in Control
• Chemical agents
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Phenolics 酚
Alcohols 醇
Heavy metals 重金属
Halogens 卤素
Detergents 去污剂
Aldehydes 醛
• Factors affecting the results
– Nature, concentration and acting time
of the disinfectant
– Type and amount of the microbe
– Temperature
– pH
– Organic matter