This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Microbiology (Sterilization and Bacterial Genetics), Subject name: Microbiology
Tyndallization is a method of sterilization using; 
Select and explain. 
A. Moist heat above 100 C, B. Moist heat below 100 C, C. Dry heat above 100 C, D. Moist heat at 100 C
D: Moist heat at 100 C
Answer: D: Moist heat at 100 C 
Explanation: Tyndallization or intermittent sterilization uses moist heat at 100 C for 20 minutes for 3 consecutive days. 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.