Which organism is used for quality control in a dry heat oven?

The organism utilized for quality control in a dry heat oven is Bacillus subtilis. This bacterium is a spore-forming organism, which means it can produce spores that are resistant to high temperatures and extreme environmental conditions. When performing quality control for sterilization processes like those using a dry heat oven, it's essential to test the effectiveness of the sterilization method against a heat-resistant organism. Bacillus subtilis spores serve this purpose well because if they are killed during the sterilization process, it verifies that the method is effective at the necessary temperature and exposure time.

In contrast, when evaluating the other organisms mentioned:

• Bacillus stearothermophilus is more commonly associated with steam sterilization and autoclaving, as it possesses spores that are highly resistant to moist heat rather than dry heat.

• Staphylococcus aureus is not a spore-forming bacterium and is more relevant in contexts involving pathogenicity and antibiotic resistance rather than heat resistance.

• Salmonella typhi is typically associated with foodborne illnesses and is not utilized in quality control for heat sterilization as it lacks the spore-forming capabilities that Bacillus species possess.

Thus, Bacillus subtilis is the most suitable choice for assessing the efficacy of sterilization