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Basic Characters of Bacteria
Hope Tan
Size and ShapesSize and Shapes
Size:Size:
Unit for measurementUnit for measurement ::
Micron orMicron or micrometer, μm: 1...
coccus bacillus
Spiral
bacterium
Basic shapes of batcteriaBasic shapes of batcteria
Cocci: sphere, 1μm
Bacilli: rods , 0.5 ~ 1 μm in width, 1~3 μm
  in length
Spiral bacteria: 1~3 μm in length and 0.3~
0.6 ...
CoccusCoccus
S. Pneumoniae N. gonorrhoeae Streptococci
Tetrads Sarcina Staphylococcus
Bacillus
S. typhi B. abortus C. diphtheriae
C. Botulinum M. tuberculosis B. anthracis
Spirillum
Vibrio
Spiral bacterium
V. cholerae
H. pylori
Basic structures
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structures
Capsule
Spore
Flagella
Pili
Structu...
Basic structure of bacteriaBasic structure of bacteria
1. Chemical composition :
A. Common component—— peptidoglycan
Also called mucopeptide or glycopeptide or
murein
Cell wallC...
• A backbone of N-acetyl glucosamine and N-A backbone of N-acetyl glucosamine and N-
acetyl muramic acid: Both discovered ...
N – acetyl-gulcosamine
N – acetyl-muramic acid
β-1,4 glucosidic bond
① Polysaccharide backbone
PeptidoglycanPeptidoglycan
...
② Tetrapeptide side chain
③ Peptide cross-bridges
Bond to N – acetyl-muramic acid
Bond to Tetrapeptide side chain and
only...
peptidoglycan forpeptidoglycan for GG++
bacteriabacteria
peptidoglycan forpeptidoglycan for GG--
bacteriabacteria
Diaminopimelic
acid
Function and medical significance of peptidoglycanFunction and medical significance of peptidoglycan ::
①① Constructure of...
Penicilin
Lysozyme
Reactive site of some antibiotics in peptidoglycan
Cell wallCell wall
1.1. Chemical composition ::
A.A. Common component—— peptidoglycan
B. Special componentB. Special compo...
Teichoic acidTeichoic acid
Structure:
Chemical composition
phosphodiester bond
Ribitol residue
Glycerine residue
Ribitol t...
Classfication
According to bonding site on the bacteria,
teichoic acid can be classified into two types
Membrane teichoic ...
teichoic acidteichoic acid
Membrane teichoic acid
Wall teichoic acid
Peptidoglycan
Teichoic
acid
Cell
wall
Phospholipid
Pr...
Function and medical significance of teichoicFunction and medical significance of teichoic
acidacid ::
① Bearing a strong ...
cell wall forcell wall for GG++
bacteriabacteria
Cell wallCell wall
1.1. Chemical composition ::
A.A. Common component—— peptidoglycan
B. Special componentB. Special compo...
Outer membraneOuter membrane
Structure
Lipopolysaccharide
lipid bilayer
Lipoprotein
Outer
membrane
Cell membrane
Periplasm...
Lipid A
Core
polysaccharide
Specific polysaccharide
(O- polysaccharide)
LPS
endotoxin
①① Adsorption and excretionAdsorption and excretion
②② Barrier function
③③ Pathogenicity
④④ AntigenicityAntigenicity
⑤⑤ Re...
Cell wall forCell wall for GG--
bacteriabacteria
Comparison of cell wall between Gram negativeComparison of cell wall between Gram negative
and Gram positive bacteriaand G...
Structures and compositions of cell wall
G + bacterium
Peptidoglycan-rich
cell wall
G+
bacterium cell wall
--Peptidoglycan...
Structures and compositions of cell wall
G-
bacterium cell wall
--Peptidoglycan
--Outer membrane
Lipoprotein
Lipid bilayer...
• Countering the effects of high intracellular osmoticCountering the effects of high intracellular osmotic
pressure and ma...
2. Wall-less forms of BacteriaWall-less forms of Bacteria
(bacteria L form)
Causes : lysozyme, penicilin, antibody, comple...
Characteristics :
• Appearance : polymorph
• Chromaticity : Gram negative
• Characteristic of cultivate : hyperosmotic
pre...
Causes :
•Lysozyme, penicillin, antibody, complements,
macropages, neutropile granulocyte, bile, UV,
etc.
Colony
Fried egg type colony
Granular type colony
Filamentous type colony
Fried egg (L) type
Granular (G) type
Filamentous (F) type
• Reversion: L-form bacteria can revert to its
normal bacteria when the cause was removed at the
early time of formation, ...
Basic structure
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structure
Capsule
Spore
Flagella
Pili
Structure...
No cholesterol
Important sturctures :
Cell membraneCell membrane
MesosomesMesosomes
Mesosomes are specialized structures f...
MesosomesMesosomes
Penecillin-binding proteins, (PBP )
Function
•Material transportation
•Respiration
• Biosynthesis :
Penicillin-binding protein
• Participate in cell division ...
Basic structures
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structures
Capsule
Spore
Flagella
Pili
Structu...
Ribosomes: numerous,
15 - 20nm in diameter with
70S; distributed throughout
the cytoplasm; site of protein
synthesis ;sens...
Plasmids: extrachromosomal genetic elements
Plasmids are small, circular , extra-
chromosomal , double-stranded DNA
molecu...
Inclusions: sources of stored energy, e,g volutin
Inclusions are aggregates of various compounds
that are normally involve...
Basic structures
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structures
Capsule
Spore
Flagella
Pili
Structu...
Lacking nuclear membrane, absence of
nucleoli, hence known as nucleic material
or nucleoid, one to several per bacterium.
...
Special structure of bacteria
Basic structures
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structures
Capsule
Spore
Flagella
Pili
Structu...
CapsulesCapsules
These are structures surrounding the
outside of the cell wall.
They are not essential to cell
viability a...
•  Antigenicity 
– Composition: polysaccharide 
•  Pathogenicity 
– Protection from phagocyte
– Resistance to drying 
– Ad...
Basic structures
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structures
Capsule
Spore
Flagella
Pili
Structu...
FlagellaFlagella
• Some bacterial species are mobile and possess
locomotory organelles - flagella. Flagella consist of
a n...
Classification
According to the number and distribution of Flagella,Flagella,
Flagella bacteria canFlagella bacteria can b...
•  Motility 
•  Pathogenicity 
– e.g., Vibrio cholerae 
•  Antigenicity 
– protein 
– also called as H Ag
Function and sig...
Basic structures
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structures
Capsule
Spore
Flagella
Pilus
Struct...
Pili are hair-like
projections of the cell ,
They are known to be
receptors for certain
bacterial viruses.
Chemical nature...
Classification:
Ordinary pili or fimbriae: fine, rigid
numerous, related to bacterial adhesion
Sex pili: longer and coarse...
Function:
Basic structures
Cell wall
Cell membrane
Cytoplasm
Nuclear material
Special structures
Capsule
Spore
Flagella
Pili
Structu...
a thick­walled form produced in a 
bacterial cell. It is very resistant to being 
killed by heat and various other chemica...
Formation and germination 
In vitro or malnutrition
In vivo or eutrophic
Bacteria (vegetative form)
spore ( only one )
Bac...
Multiple layers of resistant coats
Dipicolinic acid or calcium dipicolinate 
Low content of water
• Contains a complete nu...
Coats of sporeCoats of spore
Spore coat
Exosporium
Spore
wallCore Cortex
Endomembrane
Exomembrane
Medical significance
• Identification of a bacteria: size, appearance
and site
• Standard of sterilization
•Important sour...
Bacterial Metabolism and MultiplicationBacterial Metabolism and Multiplication
Bacterial MetabolismBacterial Metabolism
Energy MetabolismEnergy Metabolism
Important Metabolic ProductsImportant Metaboli...
Products of anabolic processes and itsProducts of anabolic processes and its
medical significancemedical significance
Pyro...
Pigments
Classification—lipo solubility, water solubility
Observation the pigments is helpful to the
identification of a b...
Bactericin
Substances produced by some strains of
bacteria and bearing the antibacterial activity to
the bacteria that rel...
The medical significance of 
these products? 
Medical significance 
Pathogenicity of 
bacteria 
Treatment of 
infectious d...
      Requirments for Bacteria GrowthRequirments for Bacteria Growth
  
1. Nutrients: 
2. Temperature 
3. Hydrogen ion con...
1.NutritionNutrition
       Factors affecting bacterial growth and division
              Nutritive material::  Water
Carb...
  2. Temperature2. Temperature
The temperature suitable for most bacteria growth is 
from 20 to 40 centigrade, but the mos...
3. hydrogen ion concentrationhydrogen ion concentration ( pH )
            The pH value that fit for most bacteria growth ...
•obligate aerobeobligate aerobe
•microaerophilic bacteriummicroaerophilic bacterium
•facultative anaerobefacultative anaer...
        The possible reasons that obligate 
anaerobe can not grow aerobically:
        1. Deficiency  of respiratory enzym...
Proliferative way: Binary fission
Bacterial Growth Curve Bacterial Growth Curve 
        The reproductive speed of most 
bacteria is very fast, while some bacteria 
such as Mycobacterium tuberculosis  
g...
Generation time : The time takes for a 
population of bacteria to double in number 
• many common bacteria  : 20 ~ 60 min
...
Bacterial population dynamics—the growth curveBacterial population dynamics—the growth curve
time
Log Bacteria
Lag Logarit...
Lag phase 
•  No growth 
•  Active metabolism
Log phase 
•  Fast growth 
•  Typical biological properties 
– Staining 
– Shapes 
– Chemical reactions 
– Sensitivity to ...
Stationary phase 
•  Constant number of live 
cells 
•  Atypical morphological 
properties 
•  Spores, exotoxins and 
anti...
Decline phase 
•  Decreased number 
of live cells 
•  Collapse or atypical 
cells
Based on the function and the chemical components: 
  Basic Medium 
­­contains the basic nutrients for the most bacterial...
  Selective Medium 
The medium that can prevent the certain bacterial 
growth while permitting others. 
e.g. SS agar 
  ...
Double sugar iron slant 
Citrate slant
  Anaerobic Medium 
A medium for the cultivation of certain anae
robes. The medium contains reducing agent,
 such as non­...
Based on the physical state 
•   Liquid medium: 
–  Without agar. 
–  for the proliferation of bacteria. 
•   Solid medium...
Bacterial growth patterns 
•    In liquid medium: 
Superficial growth; 
Turbidity/diffuse; 
Precipitate growing; 
(sedimen...
•   In semi-solid medium: 
–  Only grow along the line of inoculation 
–  Grow diffusely
Bacterial classification
Please self-study
Summary 
2.The definitions of plasmid, capsule, flagellum, 
   pilus, spore, pyrogen, bactericin. 
1.The difference betwee...
1 basic characters of bacteria
1 basic characters of bacteria
1 basic characters of bacteria
1 basic characters of bacteria
1 basic characters of bacteria
1 basic characters of bacteria
1 basic characters of bacteria
1 basic characters of bacteria
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basic characters of bacteria

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1 basic characters of bacteria

  1. 1. Basic Characters of Bacteria Hope Tan
  2. 2. Size and ShapesSize and Shapes Size:Size: Unit for measurementUnit for measurement :: Micron orMicron or micrometer, μm: 1μm=10micrometer, μm: 1μm=10-3-3 mmmm
  3. 3. coccus bacillus Spiral bacterium Basic shapes of batcteriaBasic shapes of batcteria
  4. 4. Cocci: sphere, 1μm Bacilli: rods , 0.5 ~ 1 μm in width, 1~3 μm   in length Spiral bacteria: 1~3 μm in length and 0.3~ 0.6 μm in width
  5. 5. CoccusCoccus S. Pneumoniae N. gonorrhoeae Streptococci Tetrads Sarcina Staphylococcus
  6. 6. Bacillus S. typhi B. abortus C. diphtheriae C. Botulinum M. tuberculosis B. anthracis
  7. 7. Spirillum Vibrio Spiral bacterium V. cholerae H. pylori
  8. 8. Basic structures Cell wall Cell membrane Cytoplasm Nuclear material Special structures Capsule Spore Flagella Pili Structure of bacteriaStructure of bacteria
  9. 9. Basic structure of bacteriaBasic structure of bacteria
  10. 10. 1. Chemical composition : A. Common component—— peptidoglycan Also called mucopeptide or glycopeptide or murein Cell wallCell wall
  11. 11. • A backbone of N-acetyl glucosamine and N-A backbone of N-acetyl glucosamine and N- acetyl muramic acid: Both discovered inacetyl muramic acid: Both discovered in GG++ and Gand G-- bacteria.bacteria. • A set of identical tetrapeptide side chainA set of identical tetrapeptide side chain attached to N-acetyl-muramic acid: differentattached to N-acetyl-muramic acid: different components and binding modes in Gcomponents and binding modes in G++ and Gand G-- bacteria.bacteria. • A set of identical peptide cross bridges: onlyA set of identical peptide cross bridges: only in Gin G++ bacteriabacteria peptidoglycan
  12. 12. N – acetyl-gulcosamine N – acetyl-muramic acid β-1,4 glucosidic bond ① Polysaccharide backbone PeptidoglycanPeptidoglycan STRUCTURESTRUCTURE ::
  13. 13. ② Tetrapeptide side chain ③ Peptide cross-bridges Bond to N – acetyl-muramic acid Bond to Tetrapeptide side chain and only found in GG++ bacteria
  14. 14. peptidoglycan forpeptidoglycan for GG++ bacteriabacteria
  15. 15. peptidoglycan forpeptidoglycan for GG-- bacteriabacteria
  16. 16. Diaminopimelic acid
  17. 17. Function and medical significance of peptidoglycanFunction and medical significance of peptidoglycan :: ①① Constructure of tenacious cell wall architectureConstructure of tenacious cell wall architecture Gram positive bacteria—Gram positive bacteria—threethree-dimensional structure-dimensional structure Gram negative bacteria—Gram negative bacteria— twotwo-dimensional structure-dimensional structure ②② Target of some antibioticsTarget of some antibiotics :: For exampleFor example :: Penicilin can inhibit the binding between tetrapeptide side chain and peptide cross-bridges, while lysozyme can hydrolyze the β-1,4 glucosidic bond
  18. 18. Penicilin Lysozyme Reactive site of some antibiotics in peptidoglycan
  19. 19. Cell wallCell wall 1.1. Chemical composition :: A.A. Common component—— peptidoglycan B. Special componentB. Special component Gram positive bacteria——teichoic acidGram positive bacteria——teichoic acid Special surface proteinsSpecial surface proteins
  20. 20. Teichoic acidTeichoic acid Structure: Chemical composition phosphodiester bond Ribitol residue Glycerine residue Ribitol type Polymerizer Glycerine type
  21. 21. Classfication According to bonding site on the bacteria, teichoic acid can be classified into two types Membrane teichoic acid, also called lipoteichoic acid (LTA) Wall teichoic acid
  22. 22. teichoic acidteichoic acid Membrane teichoic acid Wall teichoic acid Peptidoglycan Teichoic acid Cell wall Phospholipid Protein Cell membrane
  23. 23. Function and medical significance of teichoicFunction and medical significance of teichoic acidacid :: ① Bearing a strong negative charge. ② Adhesive attraction, relating to pathogenicity ③ They are strongly antigenic, helpful to identify and type a bacterium
  24. 24. cell wall forcell wall for GG++ bacteriabacteria
  25. 25. Cell wallCell wall 1.1. Chemical composition :: A.A. Common component—— peptidoglycan B. Special componentB. Special component Gram positive bacteria——teichoic acidGram positive bacteria——teichoic acid Special surface proteinsSpecial surface proteins Gram negative bacteria——outer membraneGram negative bacteria——outer membrane
  26. 26. Outer membraneOuter membrane Structure Lipopolysaccharide lipid bilayer Lipoprotein Outer membrane Cell membrane Periplasmic space
  27. 27. Lipid A Core polysaccharide Specific polysaccharide (O- polysaccharide) LPS endotoxin
  28. 28. ①① Adsorption and excretionAdsorption and excretion ②② Barrier function ③③ Pathogenicity ④④ AntigenicityAntigenicity ⑤⑤ Receptor: F pilusReceptor: F pilus, phage, bacteriocin Function and medical significance ofFunction and medical significance of outer membraneouter membrane ::
  29. 29. Cell wall forCell wall for GG-- bacteriabacteria
  30. 30. Comparison of cell wall between Gram negativeComparison of cell wall between Gram negative and Gram positive bacteriaand Gram positive bacteria Characters G+ G- Strength Tenacious Curmbly Thickness Thick , 20 ~ 80nm Thin , 5 ~ 10nm Layers of peptidoglycan More , about 50 layers Few , 1 ~ 3 layers Content of peptidoglycan High , 50 ~ 80% of cell wall dry weight Little , 10 ~ 20% of cell wall dry weight Structure of peptidoglycan Three-dimensional Two-dimensional Content of carbohydrate About 45% 15-20% Teichoic acid + - Outer membrane - +
  31. 31. Structures and compositions of cell wall G + bacterium Peptidoglycan-rich cell wall G+ bacterium cell wall --Peptidoglycan -- Teichoic acid
  32. 32. Structures and compositions of cell wall G- bacterium cell wall --Peptidoglycan --Outer membrane Lipoprotein Lipid bilayer LPS Lipid-rich cell wall
  33. 33. • Countering the effects of high intracellular osmoticCountering the effects of high intracellular osmotic pressure and maintaining the cell’s characteristicpressure and maintaining the cell’s characteristic shapeshape • Barrier and protection • Participate in substance exchange of bacterial cellParticipate in substance exchange of bacterial cell Function and medical significance of cell wall • Determinate some important characters of bacteriaDeterminate some important characters of bacteria pathogenicitypathogenicity immunogenicityimmunogenicity antibiotics sensitivity chromaticity : Differentiate bacteria: G +  / G ­  
  34. 34. 2. Wall-less forms of BacteriaWall-less forms of Bacteria (bacteria L form) Causes : lysozyme, penicilin, antibody, complements, macrophage, neutrophile granulocyte, bile, UV, etc. Definition : bacteria that the cell wall was impaired but maintain the competence of growth and cell division L form of Gram positive bacteria —— protoplast L form of Gram negative bacteria —— spheroplast
  35. 35. Characteristics : • Appearance : polymorph • Chromaticity : Gram negative • Characteristic of cultivate : hyperosmotic pressure, low concentrated agar with serum, and it grows very slow
  36. 36. Causes : •Lysozyme, penicillin, antibody, complements, macropages, neutropile granulocyte, bile, UV, etc.
  37. 37. Colony Fried egg type colony Granular type colony Filamentous type colony
  38. 38. Fried egg (L) type Granular (G) type Filamentous (F) type
  39. 39. • Reversion: L-form bacteria can revert to its normal bacteria when the cause was removed at the early time of formation, the determinant condition is whether there is peptidoglycan remaining in the cell wall. And if it is subcultivated for many times in vitro, it can never be reverted. •Pathogenicity : L-form bacteria bearing virulence ( diagnosis ) • Antibiotic sensitivity : changed ( cure )
  40. 40. Basic structure Cell wall Cell membrane Cytoplasm Nuclear material Special structure Capsule Spore Flagella Pili Structure of bacteriaStructure of bacteria
  41. 41. No cholesterol Important sturctures : Cell membraneCell membrane MesosomesMesosomes Mesosomes are specialized structures formed by retractable, folded and curled cytoplasmic membrane, and divided into septal and lateral mesosome. also called chondroid.
  42. 42. MesosomesMesosomes Penecillin-binding proteins, (PBP )
  43. 43. Function •Material transportation •Respiration • Biosynthesis : Penicillin-binding protein • Participate in cell division : mesosome
  44. 44. Basic structures Cell wall Cell membrane Cytoplasm Nuclear material Special structures Capsule Spore Flagella Pili Structure of bacteria
  45. 45. Ribosomes: numerous, 15 - 20nm in diameter with 70S; distributed throughout the cytoplasm; site of protein synthesis ;sensitive to streptomycin and erythromycin CytoplasmCytoplasm Composed largely of water, together with proteins, nucleic acid, lipids and small amount of sugars and salts
  46. 46. Plasmids: extrachromosomal genetic elements Plasmids are small, circular , extra- chromosomal , double-stranded DNA molecules. They are capable of self-replication and contain genes that confer some important properties, such as antibiotic resistance , virulence factors. Plasmids are not essential for cellular survival.
  47. 47. Inclusions: sources of stored energy, e,g volutin Inclusions are aggregates of various compounds that are normally involved in storing energy reserves or building blocks for the cell. Inclusions accumilate when a cell is grown in the presence of excess nutrients and they are often observed under laboratory conditions.
  48. 48. Basic structures Cell wall Cell membrane Cytoplasm Nuclear material Special structures Capsule Spore Flagella Pili Structure of bacteria
  49. 49. Lacking nuclear membrane, absence of nucleoli, hence known as nucleic material or nucleoid, one to several per bacterium. Nuclear material
  50. 50. Special structure of bacteria
  51. 51. Basic structures Cell wall Cell membrane Cytoplasm Nuclear material Special structures Capsule Spore Flagella Pili Structure of bacteria
  52. 52. CapsulesCapsules These are structures surrounding the outside of the cell wall. They are not essential to cell viability and some strains within a species will produce a capsule, whilst others do not. Capsules are often produce in vivo or on a eutrophic medium and lost during in vitro culture.
  53. 53. •  Antigenicity  – Composition: polysaccharide  •  Pathogenicity  – Protection from phagocyte – Resistance to drying  – Adherence Function and medical significance Formation condition In vivo or eutrophic
  54. 54. Basic structures Cell wall Cell membrane Cytoplasm Nuclear material Special structures Capsule Spore Flagella Pili Structure of bacteria
  55. 55. FlagellaFlagella • Some bacterial species are mobile and possess locomotory organelles - flagella. Flagella consist of a number of proteins including flagellin •The diameter of a flagellum is thin, 20 nm, and long with some having a length 10 times the diameter of cell. Due to their small diameter, flagella cannot be seen in the light microscope unless a special stain is applied. Bacteria can have one or more flagella arranged in clumps or spread all over the cell.
  56. 56. Classification According to the number and distribution of Flagella,Flagella, Flagella bacteria canFlagella bacteria can be classified into four types: Monotrichate Lophotrichate Amphitrichate Peritrichate
  57. 57. •  Motility  •  Pathogenicity  – e.g., Vibrio cholerae  •  Antigenicity  – protein  – also called as H Ag Function and significance
  58. 58. Basic structures Cell wall Cell membrane Cytoplasm Nuclear material Special structures Capsule Spore Flagella Pilus Structure of bacteria
  59. 59. Pili are hair-like projections of the cell , They are known to be receptors for certain bacterial viruses. Chemical nature is pilin Pilus
  60. 60. Classification: Ordinary pili or fimbriae: fine, rigid numerous, related to bacterial adhesion Sex pili: longer and coarser, only 1-4, related to bacterial conjugation
  61. 61. Function:
  62. 62. Basic structures Cell wall Cell membrane Cytoplasm Nuclear material Special structures Capsule Spore Flagella Pili Structure of bacteria
  63. 63. a thick­walled form produced in a  bacterial cell. It is very resistant to being  killed by heat and various other chemical  and physical agents. Spore
  64. 64. Formation and germination  In vitro or malnutrition In vivo or eutrophic Bacteria (vegetative form) spore ( only one ) Bacteria (vegetative form, also only one) Form conditions (Dormant cell)(Dormant cell)
  65. 65. Multiple layers of resistant coats Dipicolinic acid or calcium dipicolinate  Low content of water • Contains a complete nucleus material, ribosomes and energy-generating components • Highly resistant to heat, dessication, and chemicals Reasons High-pressure steam sterilization is the most effective way to kill the spores Characteristics:
  66. 66. Coats of sporeCoats of spore Spore coat Exosporium Spore wallCore Cortex Endomembrane Exomembrane
  67. 67. Medical significance • Identification of a bacteria: size, appearance and site • Standard of sterilization •Important source of infection —— anthrax, tetanus, etc.
  68. 68. Bacterial Metabolism and MultiplicationBacterial Metabolism and Multiplication
  69. 69. Bacterial MetabolismBacterial Metabolism Energy MetabolismEnergy Metabolism Important Metabolic ProductsImportant Metabolic Products 1. Catabolic processes1. Catabolic processes 2. Anabolic processes2. Anabolic processes
  70. 70. Products of anabolic processes and itsProducts of anabolic processes and its medical significancemedical significance Pyrogen : a fever-producing substance mainly synthesized by gram negative bacteria, it is highly resistant to heat and it has the property of pyrogenicity. It is a very important microbial contamination evaluation index of biological products. Toxins and Invasive Enzymes : Toxins: endotoxin, exotoxin Invasive Enzymes: hyaluronidase, streptokinase, streptodornase, and so on.
  71. 71. Pigments Classification—lipo solubility, water solubility Observation the pigments is helpful to the identification of a bacteria. Antibiotics Substance produced by some microbes and bearing the property of inhibition or killing effect to some other microbe or tumor cells.
  72. 72. Bactericin Substances produced by some strains of bacteria and bearing the antibacterial activity to the bacteria that related to bactericin-produce one. Vitamins
  73. 73. The medical significance of  these products?  Medical significance  Pathogenicity of  bacteria  Treatment of  infectious diseases  Identification of  bacteria  Products Pyrogen  Toxin  Invasive enzyme  Antibiotic  Vitamin  Bacteriocin  Pigment 
  74. 74.       Requirments for Bacteria GrowthRequirments for Bacteria Growth    1. Nutrients:  2. Temperature  3. Hydrogen ion concentration ( pH )  4. Oxygen Requirements 5. Osmotic pressure
  75. 75. 1.NutritionNutrition        Factors affecting bacterial growth and division               Nutritive material::  Water Carbon source Nitrogen source Minerals Growth factors etc.etc.       Requirments for Bacteria GrowthRequirments for Bacteria Growth
  76. 76.   2. Temperature2. Temperature The temperature suitable for most bacteria growth is  from 20 to 40 centigrade, but the most appropriate  temperature for cultivation of pathogenic bacteria is 37  centigrade. • Psychrophilic forms ( 15-20℃ ) • Mesophilic forms  ( 30-37℃ ): Include all human       pathogens and opportunists.  • Thermophilic forms  ( 50-60℃ )
  77. 77. 3. hydrogen ion concentrationhydrogen ion concentration ( pH )             The pH value that fit for most bacteria growth is The pH value that fit for most bacteria growth is  from 7.2 to 7.6,  but some bacteria grow well in from 7.2 to 7.6,  but some bacteria grow well in acidity  environment, while some bacteria just at the opposite.environment, while some bacteria just at the opposite.         According to the appropriate pH value, bacteria  can be classified into three groups just as follows: • Neutrophiles ( 5 to 8 ) • Acidophiles ( below 5.5 ) • Alkaliphiles ( above 8.5 )
  78. 78. •obligate aerobeobligate aerobe •microaerophilic bacteriummicroaerophilic bacterium •facultative anaerobefacultative anaerobe •  obligate anaerobeobligate anaerobe         According to the oxygen requirement,  bacteria can be classified into four classes as  follows:  4.Essential gaseous environment :: OO22 and CO and CO22
  79. 79.         The possible reasons that obligate  anaerobe can not grow aerobically:         1. Deficiency  of respiratory enzyme bearing high  redox potential         2. Deficiency of enzymes that degrade toxic oxygen  group, such as superoxide dismutase(SOD), catalase and  peroxidase.
  80. 80. Proliferative way: Binary fission Bacterial Growth Curve Bacterial Growth Curve 
  81. 81.         The reproductive speed of most  bacteria is very fast, while some bacteria  such as Mycobacterium tuberculosis   grows very slow. Reproductive speed :
  82. 82. Generation time : The time takes for a  population of bacteria to double in number  • many common bacteria  : 20 ~ 60 min •most common pathogens in the body : 5 ~ 10       hours •Mycobacterium tuberculosis  in medium: 18 ~ 20       hours
  83. 83. Bacterial population dynamics—the growth curveBacterial population dynamics—the growth curve time Log Bacteria Lag Logarithmic Stationary Decline Live cell number
  84. 84. Lag phase  •  No growth  •  Active metabolism
  85. 85. Log phase  •  Fast growth  •  Typical biological properties  – Staining  – Shapes  – Chemical reactions  – Sensitivity to antimicrobial agents
  86. 86. Stationary phase  •  Constant number of live  cells  •  Atypical morphological  properties  •  Spores, exotoxins and  antibiotics produced
  87. 87. Decline phase  •  Decreased number  of live cells  •  Collapse or atypical  cells
  88. 88. Based on the function and the chemical components:    Basic Medium  ­­contains the basic nutrients for the most bacterial growth;  ­­the base of other kind of media.  ­­e.g. broth.    Nutrient Medium/Enriched Medium  Additional or special nutrients (e.g., serum, growth  factors, trace elements) are added to support some  fastidious bacterial growth.  e.g. blood agar. Cultivation of Bacteria
  89. 89.   Selective Medium  The medium that can prevent the certain bacterial  growth while permitting others.  e.g. SS agar    Differential Medium  Some special substrates and indicators are added  into the media in order to produce a visual differ entiation  When several bacteria grow on the same kind of  medium. e.g. EMB agar (Eosin­ methylene blue agar).
  90. 90. Double sugar iron slant  Citrate slant
  91. 91.   Anaerobic Medium  A medium for the cultivation of certain anae robes. The medium contains reducing agent,  such as non­saturation fatty acid.
  92. 92. Based on the physical state  •   Liquid medium:  –  Without agar.  –  for the proliferation of bacteria.  •   Solid medium:  –  1.5­2.5% agar.  –  for the isolation and identification of bacteria  –  e.g., slant, Petri dishes/plates.  •   Semisolid medium:  –  0.3­0.5% agar.  – for the observation of bacterial motility and  preservation of bacteria.
  93. 93. Bacterial growth patterns  •    In liquid medium:  Superficial growth;  Turbidity/diffuse;  Precipitate growing;  (sediment)  •   In solid medium:  Confluent growth / Smear : a cluster of microorganisms growing  on a solid medium.  Colony:  It is directly visible  and arises from a single cell.
  94. 94. •   In semi-solid medium:  –  Only grow along the line of inoculation  –  Grow diffusely
  95. 95. Bacterial classification Please self-study
  96. 96. Summary  2.The definitions of plasmid, capsule, flagellum,     pilus, spore, pyrogen, bactericin.  1.The difference between G +   cell wall and G ­   cell wall    3. Medical importance of four special structures 4.The characteristics of growth curve 

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