What does a bacterial colony represent?

A bacterial colony represents a large cluster of bacterial cells that originate from a single clonal cell. This means that all the cells in the colony are genetically identical, having arisen from the division of one bacterium. When bacteria are cultured on a solid medium, each colony starts from a single original cell that divides and multiplies, forming a visible group. This characteristic makes colonies valuable in microbiology for isolating specific strains, studying their characteristics, and performing experiments.

In contrast, a mix of different bacterial cells would not form a distinct colony since the cells would come from different origins and not be genetically identical. Individual bacterial cells in a liquid culture do not form colonies, as they are dispersed in the liquid medium. A single type of antibiotic-resistant bacterium does not encompass the broader nature of what a colony represents, as it might limit the definition to only one specific feature, rather than the general concept of clonal growth.