BACTERIAL MORPHOLOGY AND TYPES

• Logos


  The Study of
• Two domains of prokaryotic organisms

  • Bacteria
  • Archaea
• Three phenotypic categories of Bacteria

  • Gram negative and have a cell wall
  • Gram positive and have a cell wall
  • Those that lack cell wall

  
• Characteristics of Bacteria and Archaea

  • Cell shape & morphological arrangements
  • Staining reactions
  • Motility
  • Colony morphology
  • Atmospheric requirements
  • Nutritional requirements
  • Biochem & Metabolic activities
  • Specific enzymes
  • Pathogenicity
  • Genetic composition

  
• Three basic shapes of bacteria

  • Round/Spherical (cocci)
  • Rectangular/Rod-shaped (bacilli)
  • Curved and spiral-shaped (spirilla)

  
• Cocci


  Spherical shaped
• Morphological types of cocci

  • Diplococci
  • Streptococci
  • Staphylococci
  • Tetrads
  • Sarcina

  
• Diplococci


  Cocci in pairs; coffee-bean shaped; kidney-bean shape
• Streptococci


  Cocci in string; Appear in long chains (chain should be longer than 10 cocci)
• Staphylococci


  Colonies of cocci that are irregular (grape-like); appear in clusters

  
• Tetrads


  Groups of 4 organized in the same plane
• Sarcina


  Eight cocci arranged in cuboidal pattern
• Bacilli


  Rod or sausage shapes that are Gram (-) except for Sporeformers, Mycobacterium, Corynebacterium, etc
• Types of bacilli


  • Sporing bacilli
  • Nonsporing bacilli
  • Coccobacilli

  
• Sporing bacilli


  There is an endospore or a spore inside the bacteria

  
• Nonsporing bacilli


  Diplobacilli (pair)
• Coccobacilli


  Bacilli in short rods or ovals; "plump-shaped"
• Types of nonsporing bacilli

  • Nonsporing snapping diplobacilli
  • Nonsporing slipping diplobacilli
• Nonsporing slipping diplobacilli


  Parallel, side by side
• Spiral


  Gram (-) microorganisms, stain used is usually DILUTE CARBOLFUCHSIN
• Types of spiral bacteria

  • Vibrio
  • Spirochetes
  • Spirillum

  
• Vibrio


  Curve rod-shaped, comma shaped
• Spirochetes


  Spiral/helical. Jump long axis that bends when in motion
• Spirillum


  Long axis remains rigid when in motion; rigid in motion, bird in flight, sometimes in "n" or "r" form
• All cocci are GRAM (+) except Neisseria SP. (N. gonorrheae)

  
• All Bacilli are GRAM (-) EXCEPT Bacillus SP. & Mycobacterium SP.
• Gram positive


  When viewed under the microscope, it appears violet in color
• Gram negative


  When viewed under the microscope, it appears read in color