Colony Description

To accurately describe a colony  the following traits should be taken into account:

• 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 the colony