Tyndallization (intermittent sterilization) is used to sterilize heat-labile materials that cannot withstand autoclaving. It involves heating at 100°C for 30 minutes on three consecutive days with incubation at 37°C between sessions. This is specifically effective because:
- A The high temperature kills all vegetative organisms and spores in a single session
- B Repeated heating denatures the spore coat proteins causing structural disintegration
- C Incubation periods allow surviving spores to germinate into heat-sensitive vegetative forms, which are killed in the next heating cycle ✓
- D Boiling at 100°C generates superheated steam that penetrates spores
Correct answer: C. Incubation periods allow surviving spores to germinate into heat-sensitive vegetative forms, which are killed in the next heating cycle
Explanation
Tyndallization works by exploiting the spore germination cycle. Heating at 100°C (boiling water or streaming steam) for 30 minutes kills vegetative organisms but NOT spores. The 37°C incubation period allows residual spores to germinate into vegetative forms. The next heating cycle then kills those vegetative forms. Three cycles ensure elimination of all sporadic germination events. It is suitable for media, culture broth, and materials that cannot withstand autoclave temperatures.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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