Topic 4: growing microbes

• Culture based studies


  Consist of: Media, Aseptic conditions, Pure and mixed cultures, Analysis of growth and characteristics
• Steps for culture


  1. Sample collection

  2. Inoculation (agar)

  3. Incubation

  4. Isolation

  5. Inspection

  6. Identification
• Construction for media


  • Carbon source
  • Energy source
  • Basal salts
  • Other supplements
  • Liquid/solid
  • Sterilisation
• Broth media


  Liquid and clear for turbidity
• Agar media


  Solid and single colonies
• Types of media


  • Synthetic: particular colony
  • Complex: as many
  • Selective: gram negative bacteria
  • Differential
• General purpose media


  Designed to grow many organisms or a particular one
• Enriched media


  Promotes growth often fastidious microbes, mainly grows pathogens
• Groups in enriched media

  • Beta Haemolysis: complete breakdown
  • Partial breakdown
  • None
• Morphology


  • Colour
  • Shape
  • Margin
  • Elevation
• Aseptic conditions


  • Sterile conditions like autoclave
  • Aseptic conditions like physical barrier
• Pure culture


  One type of microorganism
• Techniques


  • Agar plates
  • Liquid medium
  • Micromanipulator
• Total counts


  All the organisms, including: Direct: micro determined of cell number, Optical density: turbidity
• Viable counts


  Living cells, including: Plate count: serial dilutions, MPN (most probable number): serially dilutions a sample liquid in broth culture