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Chapter 1 Morphology and properties of bacteria

Chapter 1 Morphology and properties of bacteria. Belong to the prokaryote kingdom,the absence of a nuclear membrane and mitotic apparatus and the absence of other organelle besides the ribosome. Section 1 Size and shapes of bacteria. Sizes. The unit of measurement is micrometer (μm).

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Chapter 1 Morphology and properties of bacteria

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  1. Chapter 1 Morphology and properties of bacteria Belong to the prokaryote kingdom,the absence of a nuclear membrane and mitotic apparatus and the absence of other organelle besides the ribosome.

  2. Section 1 Size and shapes of bacteria Sizes The unit of measurement is micrometer (μm)

  3. basic shapes • Spherical: coccus • Straight rod: bacillus • Curved or spiral: vibrio or spirillum • Uncharacteristic (e.g., filamentous, pleomorphic, etc.)

  4. Arrangements • cocci In one plane: Diplococcus Streptococcus In two planes: Tetrad In three planes: Sarcina In random planes:Staphylococcus

  5. Coccus Division in plane （Diplococcl） Neisseria Streptococcus Division in two planes （Chain） （Tetrad） Division in three planes Tetrad （Sarcina） Sarcina Division in Multi- planes Staphylococcus （Clustor） Cell Arrangement

  6. （1）diplococcus S. pneumoniae gonococcus

  7. （2）streptococcus α-hemolytic streptococcus

  8. （3）staphylococcus S. aureus

  9. Arrangements • Bacilli Only in one plane Bacillus Streptobacillus Coccobacillus

  10. bacillus dysenteriae (gram staining)

  11. Bacillus tuberculosis(acid fast stain)

  12. Arrangements • Spiral bacteria in single cells

  13. Section 2 Structures of Bacterial cells • Basic Cell wall Cellular membrane Cytoplasm nucleoid • Special Capsule Flagellum Pilus Spore

  14. Bacterial structure

  15. Cell wall-Components

  16. Cell wall-Components • Peptidoglycan Backbone: alternating N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) A set of identical tetrapeptide side chains A set of identical pentapeptide cross bridges(G+)

  17. peptidoglycan N-acetylglucosamine N-acetylmuramic acid Lysozyme breaks this bond L-ala D-glu L-lys D-ala D-ala L-ala D-glu m-DAP D-ala D-ala penicillin pentaglycine bridge Staphylococcus aureus 金黄色葡萄球菌 E.coli 大肠杆菌

  18. Cell wall-Components • Teichoic acid: Organisms: G+bacteria Types: the wall teichoic acid the membrane teichoic acid Function: acts as a specific antigenic determinant Relation to pathogenicity

  19. Wall teichoic acid (LTA)

  20. Cell wall-Components • Outer membrane Organisms: G-bacteria Composition: Lipoprotein Lipid bilayer Lipopolysaccharide (LPS): lipid A core polysaccharide O-polysaccharide

  21. Outer membrane Functions: prevents toxic materials from entering functions as a harmful endotoxin possesses the property of antigenic specificity

  22. GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur Gln-Mur Gln-Mur Gln-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GlN-Mur GRAM POSITIVE Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Cytoplasm GRAM NEGATIVE Lipopolysaccharide Porin Outer Membrane Braun lipoprotein Periplasmic space Inner (cytoplasmic) membrane Cytoplasm

  23. Properties of the cell walls of Gram-positive and Gram-negative bacteria

  24. Cell wall Functions • gives the bacterium its shape • Protecting the cell • Constituting major surface antigens • Permitting the free diffusion of low-molecular-weight hydrophilic compounds • Having pathogenic material Gram-positive Gram-negative

  25. The mechanism of some antibiotics and enzymes killing bacteria • penicillin: Binds to transpeptidase and blocks the formation of whole cell wall of Gram-positive bacteria • Lysozyme: Destroys the peptidoglycan by cleaving the β-1,4 glycosidic bonds between NAM and NAG G+ G-

  26. G+ and G- N-acetylglucosamine N-acetylmuramic acid Lysozyme breaks this bond L-ala D-glu L-lys D-ala D-ala L-ala D-glu m-DAP D-ala D-ala penicillin pentaglycine bridge Staphylococcus aureus E.coli

  27. Penicillin and cephalosporin • Results of enzyme digestion:Protoplast Spheroplast

  28. L forms • Definition: bacteria that their peptidoglycan is destroyed or lost by various factors but they can survive under highly osmotic environment. • Types: Protoplasts(G+) and spheroplasts (G-) • Shape: polymorphism • Staining property: gram-negative • Grow environment:high osmotic • Pathogenicity: chronic

  29. A.Colony of normal bacteria B.fried egg colony of L-form bacteria C.Granular colony of L-form bacteria D.filamentous colony of L-form bacteria

  30. L forms are able to grow and divide • Caused by antibiotic • Some L forms can revert to the normal form upon removal of the inducing stimulus

  31. producing chronic infections,being resistant to antibiotic treatment.

  32. B.Cell membrane(Cytoplasmic membrane) • Composition: composed primarily of proteins and lipids. • It is a thin,elastic cytoplasmic membrane,which is 5～10nm thick • Visible in some ultrathin sections • Examined with the electron microscope

  33. Function active transport respiratory chain component biosynthesis excretion

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