Sterilization of Glassware; Preparation and Sterilization of Media
- 107 Downloads
Sterilization (Latin sterilis meaning barren) is the complete removal or inhibition of all live forms (living cell, spores, virus, etc.) from any object or place. Petri plates, flasks, beakers, pipettes, etc. are some of the generally required glassware in microbiological laboratories. Sterilization of glassware by moist heat using autoclaving is not very effective since moisture enters the glassware and may cause contamination problems. The most effective and used method of sterilization of glassware is dry heat treatment using hot air oven. On exposing the glassware to dry heat, the inhibition in growth occurs due to denaturation of proteins and oxidation of biomolecules. Duration of sterilization is temperature dependent: at higher temperature sterilization is achieved faster, i.e., at 170 °C, 30 min; 160 °C, 60 min; and 150 °C, 150 min or longer. Spores of Bacillus atrophaeus are used as biological indicator to test the efficacy of sterilization process. Since glasswares are sensitive to rapid changes in temperature, they are wrapped in paper and then only kept in hot air oven.