A visible group of bacteria growing on a solid medium is called

• A. Microbiota
• B. Biofilm
• C. Bacterial Colony
• D. Culture

Answer: (C)

A visible group of bacteria growing on a solid medium is called a bacterial colony. This occurs when a single cell (or a few cells) multiplies and forms a distinct, macroscopic lump that you can see with the naked eye. Colonies are useful because they let scientists isolate pure cultures; each colony typically arises from one progenitor cell, so picking one colony yields organisms with identical genetic material. The colony’s size, shape, edge, and color help differentiate different organisms and guide further analysis. This concept differs from a biofilm, which is a surface-attached community in a matrix that often forms in liquid environments rather than separate spots on an agar plate. Microbiota refers to the entire community of microorganisms in a particular environment, not a single growth on a plate, and culture can mean the growth of microorganisms in general or the medium used to grow them, not the discrete colony itself.