To accurately describe a colony the following traits should be taken
Results of a Colony Description
Size: A mm ruler should be held under a plate and used to measure
the diameter of several representative colonies, these measurements should
then be averaged and recorded.
General Shape: The shape of a colonly will have one of three general
shapes when viewed from above; round, irregular and spreading, and concentric.
Margin: The margin should be observed from above also and will represent
the outside edge of the general shape. The margin will be one of
the following; entire, undulate lobate or filamentous
Elevation: The elevation of a colony should be observed from the
side of the plate and will be characterized in the following ways; effuse
(like water on a flat surface), flat (discrete colony with a flat top),
convex (water on wax paper), umbonate (with a nipple in the center), or
umbilicate (sunken center)
Surface: The surface of the colony should be observed from the top
and will have one of the following characteristics; smooth, fliamentous,
powdery, wrinkled or ringed.
Density: This quality dexcribes if the colony is opaque or translucent
Pigment: There are three ways a colony may be pigmented; (1) Non
pigmented colonies may be described as colorless, white, or off-white,
(2) Nondiffusible pigment means that just the cell is pigmented,
while (3) Diffusible/water soluble pigments will color the agar around