第三章_灭菌.ppt

灭菌温度和灭菌时间对营养成份破坏的比较 中文名称： 露点 英文名称： dew point 定义： 空气湿度达到饱和时的温度。 133页 fermentor stream stream Cooling water Sterile medium mixing tank pump sterilizing column Maintaining tank cooling pipe What are the equipments of continuous sterilization? Question Ⅲ、连续灭菌 培养基连消工艺流程图 Continuous sterilization processes Injection sterilizers Steam is fed directly into raw medium, so that temp. rises to desired level almost immediately. Advantages Shorter sterilization time means less thermal degradation of medium. Disadvantages Insufficient for sterilizing media containing solid matter, on account of inferior rate of heat-transfer in solids. (batch process is recommended for sterilizing such media.) In a word: High temperatures for short times are used in preparing nutrient media for industrial fermentations and in pasteurizing milk, because this causes less damage to biochemicals than more prolonged times at lower temperatures. Filtration Sterilize solutions that may be damaged or denatured by high temperatures or chemical agents. The pore size for filtering bacteria, yeasts, and fungi is in the range of 0.22-0.45 μm (filtration membranes are most popular for this purpose). Filtration: Fluids Air Unit 2 Air Sterilization Very large volumes of sterile air is required in many aerobic fermentation process. Methods for air sterilization Radiation High temperature ? Electrostatic bacteria removal Filtration Air sterilization is generally carried out by filtration to remove all particles and m/o (bacteria, spores, yeast, mould) from atmospheric flow. For reason of cost, absolute sterility is neither possible nor customary in practice. For germ-filtration of liquids (hydrophobic membrane filters), the pore width is 0.2 μm. For air-filtration, the pore width of filters is over 0.45 ?m . Removal of m/o from air by the fibrous filter may occur by one, or combination of the following mechanisms: Inertial impaction Interception Diffusi