Micrococcus (mi’ krō kŏk’ Əs) is a genus of bacteria in the Micrococcaceae family. Micrococcus occurs in a wide range of environments, including water, dust, and soil. Micrococci have Gram-positive spherical cells ranging from about 0.5 to 3 micrometers in diameter and are typically appear in tetrads. Micrococcus has a substantial cell wall, which may comprise as much as 50% of the cell mass. The genome of Micrococcus is rich in guanine and cytosine (GC), typically exhibiting 65 to 75% GC-content. Micrococci often carry plasmids (ranging from 1 to 100MDa in size) that provide the organism with useful traits.

Staphylococcus (from the Greek: σταφυ λή, staphylē, "bunch of grapes" and κόκκο ς, kókkos, "granule") is a genus of Gram-positive bacteria. Under the microscope they appear round (cocci), and form in grape-like clusters.

The Staphylococcus genus include just thirty-three species. Most are harmless and reside normally on the skin and mucous membranes of humans and other organisms. Found worldwide, they are a small component of soil microbial flora.