In microbiology, what is a colony?

• A. A sterile nutrient broth used to enrich microbial growth before plating.
• B. An individual bacterial cell observed under a microscope after staining.
• C. A visible mass of microbial cells on a solid medium that typically arises from a single cell or a small cluster of cells (a colony-forming unit, CFU).
• D. A mixed population of different microbial species growing together in a liquid culture.

Answer: (C)

Verified step by step guidance

1. Understand that in microbiology, a colony refers to a visible mass of microbial cells that grow on a solid medium, such as an agar plate.
2. Recognize that a colony typically originates from a single bacterial cell or a small cluster of cells, which is often called a colony-forming unit (CFU).
3. Note that colonies are important because they allow microbiologists to isolate and study pure cultures of microorganisms, as each colony represents descendants of one original cell or CFU.
4. Differentiate a colony from other terms: it is not a sterile nutrient broth (which is a liquid medium), nor is it an individual cell observed under a microscope, nor a mixed population in liquid culture.
5. Summarize that a colony is essentially a visible cluster of genetically identical microbial cells grown on a solid surface, making it a fundamental concept in microbiological techniques.