Microbiology Techniques

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Microbiology Techniques

• A. Pure culture techniques
• Pleomorphism
• Koch/Pasteur. Gelatin gives way to AGAR

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Microbiology Techniques cont..
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Microbiology Techniques cont..
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Microbiology Techniques Culturing
microorganisms
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Microbiology Techniques cont..

• B. Sterilisation.
• Physical. Chemical. Filtration.
• Kinetics of death. Usually FIRST ORDER.
• logeNt logeNo - kt kdeath constant

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Microbiology Techniques cont..

• Thermal death point. 10ml for 10 minutes
• E.coli vegetative cells 55oC Bacillus sp
  spores 120oC
• Decimal reduction time. Time to kill 90.
• C. Use of Heat.
• 50 - 70oC vegetative cells. PASTEURISATION.
• 100oC Some spores and viruses.
• 110-120oC Most everything.
• AUTOCLAVE USUALLY 121oC 15psi
• MOIST/WET HEAT better than DRY HEAT OVENS
• D. Radiation.
• UV, X rays, gamma radiation commonly used

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Microbiology Techniques cont..

• E. Filtration.
• Usually use 0.22 ?m pore cellulose acetate/nylon
  filters. Not effective for virus removal. They
  are filterable
• F. Impaction.
• Physical force using striking action
• G. Chemical agents.
• Phenol Disinfectant Phenol Coefficient
• Halogens Cl Br
• Oxidants H2O2
• Alkylating agents Formaldehyde
• Detergents
• Metals Hg
• Alcohols

? DIRECTED READING Practical manual. Prescot.
Ch2 Microscopy Ch5 Media. Ch6 Growth