Micrococcus luteus
Micrococcus luteus is a Gram-positive, to Gram-variable, nonmotile, coccus, tetrad-arranging, pigmented, saprotrophic bacterium that belongs to the family Micrococcaceae. It is urease and catalase positive. An obligate aerobe, "M. luteus" is found in soil, dust, water and air, and as part of the normal microbiota of the mammalian skin. The bacterium also colonizes the human mouth, mucosae, oropharynx and upper respiratory tract. "Micrococcus luteus" is considered a contaminant in sick patients and is resistant by slowing of major metabolic processes and induction of unique genes. It is a high G + C ratio bacterium. "Micrococcus  luteus" is coagulase negative, bacitracin susceptible, and forms bright yellow colonies on nutrient agar. "Micrococcus luteus" has been shown to survive in oligotrophic environments for extended periods of time. Recent work by Greenblatt "et al." demonstrate that "Micrococcus luteus" has survived for at least 34,000 to 170,000 years on the basis of 16S rRNA analysis, and possibly much longer. It was sequenced in 2010 and has one of the smallest genomes of free-living Actinomycetota sequenced to date, comprising a single circular chromosome of 2,501,097 bp. Novel codon usage. "Micrococcus luteus" was one of the early examples of novel codon  usage, which led to the conclusion that the genetic code is not static, but evolves. Classification. "Micrococcus luteus" was formerly known as "Micrococcus lysodeikticus". In 2003, it was proposed that one strain of "Micrococcus luteus", ATCC 9341, be reclassified as "Kocuria rhizophila". Ultraviolet absorption. Norwegian researchers in 2013 found a "M. luteus" strain that synthesizes a pigment that absorbs wavelengths of light from 350 to 475 nano-meters. Exposure to these wavelengths of ultraviolet light has been correlated with an increased incidence of skin cancer, and scientists believe this pigment can be used to make a sunscreen that can protect  against ultraviolet light.