Micrococcus luteus is a Gram-positive, spherical, saprotrophic bacterium that belongs to the family Micrococcaceae. It is found in soil, dust, water and air, and as part of the normal flora of the mammalian skin. The bacterium also colonizes the human mouth, mucoase, oropharynx and upper respiratory tract.
It is considered a contaminant in sick patients. It is coagulase negative, bacitracin susceptible, and forms bright yellow colonies on nutrient agar.
M. luteus has been shown to survive in oligotrophic environments for long periods of time.