Lab 1

Lab 1

1. Culture Media

   • Suitable nutrients and environment favourable for growth
   • Different species differ in their requirements
   • Media can be liquid or solidified with agar (gelling agent from seaweed)
   • Culture medium must be sterilised and remind sterile prior to use
   • Culture media sterilised by autoclaving (steam under pressure)
   • Autoclaving kills vegetative and heat or chemical resistant forms of microorganisms
   • All inoculated material is autoclaved before disposal
   • Autoclaving = pressure of 15 pounds per inch^2 for 15 mins plus 121C steam temperature

2. Aseptic Transfer

   • Prevents contamination by extraneous MOs in the air, on equipment or surfaces/hands
   • Prevents contamination of lab or worker by the MOs being handled
   • When the MOs are transferred to a sterile medium, aseptic technique is used

3. Growth

   • Incubation in favourable conditions allows growth and division to occur
   • Liquid media shows growth by cloudiness
   • Solid media shows growth by presence of colonies
   • Appearance of colonies is important in identification
   • Macroscopic and microscopic appearances are different.
   • Microscopic appearance is more often used in identification

4. Differential Stain and Light Microscopy

   • Light microscope is a powerful tool for the microbiologist
   • Cells in stained samples can be observed together with their shapes, sizes and colour
   • Gram stain is used to begin the process of identifying organisms