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Bacteria ?!!

Sir azrimi. Bacteria ?!!. Bacterial Groups Most widely accepted taxonomic classification for bacteria is Bergey’s Manual of Systematic Bacteriology . 5000 bacterial species identified, 3100 classified.

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Bacteria ?!!

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  1. Sir azrimi Bacteria?!!

  2. Bacterial Groups • Most widely accepted taxonomic classification for bacteria is Bergey’s Manual of Systematic Bacteriology. • 5000 bacterial species identified, 3100 classified. • Bacteria are divided into four divisions (phyla) according to the characteristics of their cell walls. • Each division is divided into sections according to: • Gram stain reaction • Cell shape • Cell arrangements • Oxygen requirements • Motility • Nutritional and metabolic properties • Each section contains several genera.

  3. Classification of Bacteria

  4. Four Divisions of Bacteria

  5. MORPHOLOGY • Bacteria grow tremendously fast when supplied with an abundance of nutrients. • Different types of bacteria will produce different-looking colonies, some colonies may be colored, some colonies are circular in shape, and others are irregular. • The characteristics of a colony (shape, size, pigmentation, etc.) are termed the colony morphology. • Colony morphology is a way scientists can identify bacteria.

  6. Bacteria: Each distinct circular colony should represent an individual bacterial cell or group that has divided repeatedly. Being kept in one place, the resulting cells have accumulated to form a visible patch. Most bacterial colonies appear white, cream, or yellow in color, and fairly circular in shape. For example: WHAT CAN GROW ON AGAR PLATE? BACTERIA Each distinct circular colony should represent an individual bacterial cell or group that has divided repeatedly. Being kept in one place, the resulting cells have accumulated to form a visible patch. Most bacterial colonies appear white, cream, or yellow in color, and fairly circular in shape

  7. Yeasts: Yeast colonies generally look similar to bacterial colonies. Some species, such as Candida, can grow as white patches with a glossy surface

  8. Molds are actually fungi, and they often appear whitish grey, with fuzzy edges. They usually turn into a different color, from the center outwards. Two examples of molds are shown below:

  9. Structure of Bacteria

  10. Size of Bacteria • Average bacteria 0.5 - 2.0 um in diam. • RBC is 7.5 um in diam. • Surface Area ~12 um^2 • Volume is ~4 um • Surface Area to Volume is 3:1 • Typical Eukaryote Cell SA/Vol is 0.3:1 • Food enters through SA, quickly reaches all parts of bacteria • Eukaroytes need structures & organelles Chapter 4

  11. Shapes of Bacteria • Coccus • Chain = • Cluster = • Bacillus • Chain = • Coccobacillus • Vibrio = curved • ? • ? • ? • ? Chapter 4

  12. Chapter 4

  13. Structures • Flagella • Pili • Capsule • Plasma Membrane • Cytoplasm • Cell Wall • Lipopolysaccharides • Teichoic Acids • Inclusions • Spores Chapter 4

  14. Flagella • Motility - movement • Swarming occurs with some bacteria • Spread across Petri Dish • Proteus species most evident • Arrangement basis for classification • Monotrichous; 1 flagella • Lophotrichous; tuft at one end • Amphitrichous; both ends • Peritrichous; all around bacteria • Observe Picture in Micro Lab. Chapter 4

  15. Chapter 4

  16. Mono- or Lophotrichorus Chapter 4

  17. Chapter 4

  18. Pili • Short protein appendages • smaller than flagella • Adhere bacteria to surfaces • E. coli has numerous types • K88, K99, F41, etc. • Antibodies to will block adherance • F-pilus; used in conjugation • Exchange of genetic information • Flotation; increase boyancy • Pellicle (scum on water) • More oxygen on surface Chapter 4

  19. F-Pilus for Conjugation Chapter 4

  20. Capsule or Slime Layer • Glycocalyx - Polysaccharide on external surface • Adhere bacteria to surface • S. mutans and enamel of teeth • Prevents Phagocytosis • Complement can’t penetrate sugars Chapter 4

  21. Cytoplasm • 80% Water {20% Salts-Proteins) • Osmotic Shock important • DNA is circular, Haploid • Advantages of 1N DNA over 2N DNA • More efficient; grows quicker • Mutations allow adaptation to environment quicker • Plasmids; extra circular DNA • Antibiotic Resistance • No organelles (Mitochondria, Golgi, etc.) Chapter 4

  22. Cell Membrane • Bilayer Phospholipid • Water can penetrate • Flexible • Not strong, ruptures easily • Osmotic Pressure created by cytoplasm Chapter 4

  23. Chapter 4

  24. Chapter 4

  25. Chapter 4

  26. Cell Wall Peptido-glycan Polymer (amino acids + sugars) Unique to bacteria Sugars; NAG & NAM N-acetylglucosamine N-acetymuramic acid D form of Amino acids used not L form Hard to break down D form Amino acids cross link NAG & NAM Chapter 4

  27. Chapter 4

  28. Chapter 4

  29. Chapter 4

  30. Chapter 4

  31. Chapter 4

  32. Chapter 4

  33. Cell Wall Summary • Determine shape of bacteria • Strength prevents osmotic rupture • 20-40% of bacteria • Unique to bacteria • Some antibiotics effect directly • Penicillin Chapter 4

  34. Video Clip on Cell Wall Chapter 4

  35. Teichoic Acids Gram + only Glycerol, Phosphates, & Ribitol Attachment for Phages Chapter 4

  36. Chapter 4

  37. Lipopolysaccharide (LPS) Endotoxin or Pyrogen Fever causing Toxin nomenclature Endo- part of bacteria Exo- excreted into environment Structure Lipid A Polysaccharide O Antigen of E. coli, Salmonella G- bacteria only Alcohol/Acetone removes Chapter 4

  38. Chapter 4

  39. Chapter 4

  40. LPS (cont’d) • Functions • Toxic; kills mice, pigs, humans • G- septicemia; death due to LPS • Pyrogen; causes fever • DPT vaccination always causes fevers • Adjuvant; stimulates immunity • Heat Resistant; hard to remove • Detection (all topical & IV products) • Rabbits (measure fever) • Horse shoe crab (Amoebocytes Lyse in presence of LPS) Chapter 4

  41. LPS (cont’d.) • Appearance of Colonies • Mucoid = Smooth (lots of LPS or capsule) • Dry = Rough (little LPS or capsule) • O Antigen of Salmonella and E. coli • 2,000 different O Ags of Salmonella • 100’s different O Ags of E. coli • E. coli O157 • O Ags differ in Sugars, not Lipid A Chapter 4

  42. Endospores • Resistant structure • Heat, irradiation, cold • Boiling >1 hr still viable • Takes time and energy to make spores • Location important in classification • Central, Subterminal, Terminal • Bacillus stearothermophilus -spores • Used for quality control of heat sterilization equipment • Bacillus anthracis - spores • Used in biological warfare Chapter 4

  43. Chapter 4

  44. Chapter 4

  45. G+ vs. G- • G+ • Thicker cell wall • Teichoic Acids • G- • Endotoxin - LPS • Which are more sensitive to Penicllin? • Alcohol/Acetone affects which more? Chapter 4

  46. Prokaryotes vs. Eukaryotes Cell Wall Teichoic Acids LPS Endospores Circular DNA Plasmids Chapter 4

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