What Differences Can Be Observed Between Bacterial and Fungal Colonies?

Most bacterial colonies grown in culture media plates are typically white, cream or yellow in appearance and are relatively circular. Some colonies, however, may exhibit uncommon characteristics. Fungal colonies, such as molds or the fungus that causes athlete's foot, are typically large, fuzzy and become a different color as they grow outwards from their centers.

The specific characteristics of a colony are referred to as the colony's morphology, which aids in the identification of the species. In addition to the basic characteristics, some colonies can be identified by an irregular, filamentous or rhizoid form.

Turning the culture dish on its side enables the observer to note whether the colony's elevation, or cross section, is raised, convex, flat, umbonate or crateriform. An additional identifying factor is opacity; the colony may be clear, translucent, opaque or iridescent.