Intermittent sterilization

Tyndallization or Intermittent sterilization: Sugar, Egg, Serum and Gelatin containing media are sterilized by heating at 100oC for 20 mins on three successive days, using moist heat First day all vegetative forms are killed. Second day germinating spores and remaining if present killed on final day. It is carried out in a Koch and Arnold steam sterilizer. Media which contain any ingredient/component not able to tolerate the temperature of an autoclave are sterilized by tyndallization. Eg. TCBS, XLD, DCA, sugar solutions for fermentation tests and gelatin containing media. Inspissation or Fractional sterilization: Heating at 80-85oC for 30 mins on three successive days.