Microbiology Biological indicator for determining efficacy of autoclaving is: September 2009 A Pseudomonas aeruginosa B Clostridium Perfringenes C Bacillus stearothermophilus D Salmonella typhi 💡 Explanation Biological indicator for determining efficacy of autoclaving is: September 2009 ✓ Correct Answer: C. Bacillus stearothermophilus