Microbiology Practice Exam

Which organism is known for being a common beneficial microbe in the human gut?

1. Clostridium

2. Escherichia coli

3. Staphylococcus

4. Salmonella

The correct answer is: Escherichia coli

Escherichia coli is a well-studied bacterium that is commonly found in the intestines of humans and other warm-blooded organisms. It plays a significant role in gut health as a beneficial microbe. Various strains of E. coli contribute to digestion and help synthesize essential vitamins, such as vitamin K2, which is crucial for blood clotting and bone metabolism. In a healthy gut, E. coli can help create a balanced microbial environment by inhibiting the growth of pathogenic bacteria and supporting the immune system. Its presence is essential for the maintenance of gut flora, contributing to overall digestive health. On the other hand, while Clostridium includes some species that can be beneficial, such as those involved in fermentation, it is also known for producing toxins and being the cause of certain diseases. Staphylococcus includes opportunistic pathogens that can lead to infections rather than having a predominantly beneficial role. Salmonella is primarily associated with foodborne illness rather than contributing positively to gut health. Therefore, E. coli stands out as a key beneficial organism in the human gut microbiome.