The indicator used in the autoclave is?: (A) Clostridium tetani, (B) Bacillus stereothermophilus, (C) Bacillus pumilis, (D) Bacillus subtilis Var Niger
Answer is B. Sterilization control: for determining the efficacy of moist heat sterilization, spores of Bacillus stearothermophilus are used as the test organism. This is a thermophilic organism with an optimum growth temperature of 55-60oC and its spores require exposure of 12 minutes at 121oC to be killed REF:Ananthanarayan & Panicker's Textbook of Microbiology 8th edition pg no:34