Texas A&M University (TAMU) BIOL206 Introductory Microbiology Lab Practice Exam 1

The type of bacterial growth that is characterized by a crusty appearance is identified as friable. This term refers to a texture that is brittle, flaky, or crumbly, which matches the description of a crusty growth. When you observe colonies that have a dry and rough surface with a tendency to break apart easily, they are classified as friable. This is often seen in certain types of bacteria that produce pigments or have specific growth characteristics under laboratory conditions.

In contrast, spreading edge typically describes bacterial colonies that have a smooth and spreading margin, indicating more of a uniform growth across the medium. Pulvinate refers to colonies that are raised with a rounded appearance but do not exhibit the crusty texture. Flocculent describes a growth pattern that appears as clumps or flocs, presenting a more fluffy or suspended appearance instead of a crusty one. Understanding these distinctions helps in identifying the morphology of different bacterial species based on their growth patterns.