Which of the following best describes umbonate bacteria?

• A. Bacteria that produce a flat, smooth colony surface
• B. Bacteria that exhibit filamentous growth patterns
• C. Bacteria that form colonies with a raised, dome-shaped center
• D. Bacteria that form colonies with irregular, spreading edges

Answer: (C)

Verified step by step guidance

1. Understand the term 'umbonate' as it relates to bacterial colony morphology, which describes the shape and elevation of bacterial colonies on solid media.
2. Recall that colony morphology terms often describe the elevation and shape of the colony surface, such as flat, raised, convex, umbonate, etc.
3. Recognize that 'umbonate' specifically refers to colonies that have a raised center that is dome-shaped, resembling a small bump or knob in the middle of the colony.
4. Compare the given options to the definition: flat and smooth colonies do not have raised centers; filamentous growth refers to thread-like extensions, not elevation; irregular spreading edges describe colony margins, not elevation.
5. Conclude that the best description of umbonate bacteria is those that form colonies with a raised, dome-shaped center.