Which microorganism is commonly used in the production of yogurt?

Lactobacillus bulgaricus is the microorganism commonly used in the production of yogurt due to its ability to ferment lactose, the sugar found in milk. This fermentation process leads to the production of lactic acid, which gives yogurt its tart flavor and also contributes to its thick texture. The presence of lactic acid acts as a natural preservative, inhibiting the growth of harmful bacteria and making the yogurt safe for consumption. Additionally, Lactobacillus bulgaricus is a probiotic, which means it can provide health benefits such as supporting gut health.

In contrast, the other microorganisms listed do not play a role in yogurt production. Staphylococcus aureus is known for causing foodborne illnesses, Escherichia coli includes strains that can be pathogenic and cause gastrointestinal issues, and Clostridium perfringens is associated with food poisoning and not used in dairy fermentation. Each of these organisms has different characteristics and uses, making Lactobacillus bulgaricus specifically suited for the dairy fermentation process that leads to yogurt.