Which term describes all of the microorganisms that live in a particular environment, such as the human body?

• A. Microorganism
• B. Microbiome
• C. Bacteria
• D. Organisms

Answer: (B)

Think of the environment as a tiny ecosystem. The word microbiome names the whole community of microbes living there—the bacteria, fungi, viruses, and other microorganisms, plus their collective genes—such as the microbes inhabiting the human body. It isn’t just one microbe, but all of them together and their genetic material. A single microbe would be a microorganism, not the whole community. Bacteria refers to a single group of organisms, not all microbes. Organisms is a general term for living things and does not specify the microbial community in a particular environment. So the best word for all microorganisms in a given environment is microbiome.