RECIPES AND PROTOCOL
Cultures of microorganisms can be grown on any medium that is appropriate for their isolation and cultivation. Since morphology is influenced by medium type and growth conditions, care should be taken to record these parameters. Good determination of colony morphology is predicated on good streak technique because it requires good separation of colonies.
Smibert and Krieg (5) proposed the following protocol:
1. Measure the colony diameter in millimeters.
2. Describe the pigmentation (distinguishing between pigmented colonies and those secreting diffusible pigments).
3. Describe the form, elevation, and margin as indicated in Fig. 1. Also indicate whether the colonies are smooth (shiny glistening surface), rough (dull, bumpy, granular, or matte surface), or mucoid (slimy or gummy appearance).
4. Record the opacity of the colonies (transparent, translucent, or opaque) and their texture when tested with a needle: butyrous (buttery texture), viscous (gummy), or dry (brittle or powdery).
FIG. 1. Diagram illustrating the various forms, elevations, and margins of bacterial colonies (3).