<prompt> Tyndallisation is a method of -Growing bac teria in pure cultureSterilizationInoculation of mediaPreserving cultures  <response>: A single exposure of 90 minutes usually ensures sterilization but for media containing sugars or gelatin, an exposure of 100-degree Celsius for 20 minutes on 3 successive days is used. This is known as tyndallisation or intermittent sterilization REF:Ananthanarayan and Panickers Textbook ofMicrobiology 8thEdition pg no:32 