|Description:||This photograph depicted a QUAD Plate containing a xanthine growth media upon which Nocardia and Streptomyces Gram-positive bacterial colonies were grown. The results here were two positive, i.e., the ability for the organisms to decompose xanthine, and two negative growth patterns. Positive results appear as a clear halo around the colonies, while a negative result manifests as an absence of this clear halo, and instead one will note the deposition of a melanin-like pigment.|
Both genera are members of the order Actinomycetales. These colonies were grown in an aerobic environment, which means these organisms thrive in the presence of oxygen.