1. ©M J Larkin Biological Sciences. The Queen’s University of Belfast. Microbiology Techniques A. Pure culture techniques Pleomorphism Koch/Pasteur. Gelatin gives way to AGAR

2. ©M J Larkin Biological Sciences. The Queen’s University of Belfast. Microbiology Techniques cont…..

3. ©M J Larkin Biological Sciences. The Queen’s University of Belfast. Microbiology Techniques cont…..

4. ©M J Larkin Biological Sciences. The Queen’s University of Belfast. Microbiology Techniques – Culturing microorganisms

5. ©M J Larkin Biological Sciences. The Queen’s University of Belfast. Microbiology Techniques cont….. B. Sterilisation. Physical. Chemical. Filtration. Kinetics of death. Usually FIRST ORDER. log e N t =log e N o - kt k=death constant N t log e N t

6. ©M J Larkin Biological Sciences. The Queen’s University of Belfast. Microbiology Techniques cont….. Thermal death point. 10ml for 10 minutes E.coli vegetative cells 55 o C Bacillus sp spores 120 o C Decimal reduction time. Time to kill 90%. C. Use of Heat. 50 - 70 o C vegetative cells. PASTEURISATION. 100 o C Some spores and viruses. 110-120 o C Most everything. AUTOCLAVE USUALLY 121 o C 15psi MOIST/WET HEAT better than DRY HEAT OVENS D. Radiation. UV, X rays, gamma radiation commonly used

7. ©M J Larkin Biological Sciences. The Queen’s University of Belfast. 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 H 2 O 2 Alkylating agents Formaldehyde Detergents Metals Hg Alcohols  DIRECTED READING: Practical manual. Prescot. Ch2 Microscopy Ch5 Media. Ch6 Growth