Sarcina lutea is a yellow, spherical, gram-positive bacteria. It has a one-layer cell wall that comprises carbohydrates and proteins. It is capable of causing skin infections in immune-compromised individuals.
Sarcina lutea is an older name for the bacteria Micrococcus luteus; the coccus portion of the name refers to the bacteria's spherical shape. Micrococcus luteus is part of the natural human flora where it inhabits the skin, mouth and upper respiratory tract. It is a ubiquitous bacteria that also inhabits the soil, water and air. It is typically harmless but capable of causing skin infections given an already weak immune system.
This bacteria is similar to another, more harmful, species, Staphylococcus aureus. Because Microcococcus luteus is vulnerable to the antibiotic bacitracin, the addition of bacitracin to a bacterial culture confirms bacterial identification. Micrococcus luteus has a tiny genome, among the smallest in the bacterial world, comprising one circular chromosome.
Research reveals that certain strains of Micrococcus luteus absorb light at wavelengths of 350 to 475 nanometers; no current sunscreen is capable of this. These longer wavelengths are responsible for increasing the chance of skin cancer due to sun exposure. As of 2014, researchers are working on isolating the genes responsible for this protective quality in Micrococcus luteus for the development of super-protective sunscreens.