Topic 2: Cultivation of Bacteria

• Bacteria must be grown on culture media in order to characterize and identify.
• Bacteria require sources of energy, carbon, nitrogen, minerals, and growth factors
• Most bacteria are chemoheterotrophs
  • require organic compounds for carbon and energy sources
• Bacteria exhibit a wide range of nutritional requirements, need enriching nutrients
  • milk, serum, blood, tomato juice
• Growth factors: organic compounds such as vitamins or amino acids that are incorporated into a cell without alteration
• First bacterial cultures were grown in broth/liquid media - infusions and blood
• Robert Koch attempted to culture bacteria on potato slices when he realized need for solid media.
  • Added gelatin to liquid media when some bacteria wouldn’t grow on potato → however, gelatin liqueified under incubation conditons
  • Angelina Hess suggested use of agar as solidfying agent
  • Today, agar is the most commonly used solidifying agent in culture media
• Aseptic technique is used in microbiology to exclude contaminants
  • prevention of unwanted microorganisms in laboratory and medical procedures

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