Sterilization objects - Microbiological glassware (test tubes, Petri dishes, flasks, etc.)
- Media for growing microorganisms
- Boxes and rooms in which work with microbiological objects is carried out
- Waste materials (tips, Petri dishes, smears, etc.)
Types of sterilization: - saturated high-temperature water steam (steam sterilization),
- dry hot air (heat sterilization )
- gas (gas sterilization), (for example ethylene oxide – colorless gas)
- chemicals (chemical sterilization), 2% alkaline aqueous solution of glutaraldehyde and 20% solution of formaldehyde in 70% ethanol.
- radiation method (radiation sterilization),
- filtration through fine-pored filters (mechanical sterilization),
- repeated heating of liquids in a water bath at 100 0 C (fractional sterilization) or 56 0 C (tindalization ).
- Thermal – burning and boiling , single heating at 100 0 C
- UV irradiation is not a sterilization method, since it does not ensure complete destruction of microorganisms, especially spores.
Steam sterilization (autoclave)
Sterilization temperature 100–1 45° C
Steam pressure 0.4-2.5 atmospheres
- Packaging: bags, craft bags , laminate paper , calico.
- Materials: polymers, glass, latex, fabric, corrosion-resistant metals.
- Advantages: high vapor permeability, large selection of packaging, sterility lasts longer, cheap and easy to use method.
- Disadvantages: moistening of products, causes corrosion of metals.
Heat sterilization
Sterilization conditions:
at 180 0 C – 1/2 hour,
at 170 0 C – 1 hour,
at 160 0 C – 2 hours,
at 150 0 C – 2.5 hours,
at 140 0 C – 3 hours,
at 120 0 C – 6 hours.
- Packing: craft bags , calico.
- Materials: metal, textiles. Advantages: cheap, simple method, does not cause metal corrosion, does not wet the packaging and products.
- Disadvantages: limited choice of packaging, slow and uneven heating of products, the need to use higher temperatures, the inability to use materials made of rubber and polymers.
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