The six recognised
Ureaplasma species have a
GC content of 27 to 30 percent and a
genome size ranging from 0.76 to 1.17 million
base pairs, and
cholesterol is required for
growth. A defining characteristic of the genus is that they perform
urea hydrolysis, which creates ammonia as a product. Some strains originally classified as
U. urealyticum should be treated as a new species,
U. parvum. Their sequences can be accessed through public records and databases. Most of the 16S rDNA sequence of the two strains constitute the exact same nucleotides bases (97.3% homology), yet small differences have been acknowledged. Due to the direct similarity and the increased variation in other species of
Ureaplasma, it is thought that the two strains of
Ureaplasma urealyticum (T960 and 27) have evolutionary diverged together. In the same study conducted, using the same 16s rDNA aligned sequences, they concluded all the mammalian strains diverged and coevolved with their corresponding species (canine, feline, human, bovine) during the Cretaceous period. It was found that the most closely related species strain of
Ureaplasma to
Ureaplasma urealyticum was
Ureaplasma diversum (isolated from bovine). == Gram staining ==