Genome Size and Base Composition of Deoxyribonucleic Acid from Eight Human T-Mycoplasmas

The base compositions of the deoxyribonucleic acid and the genome sizes of eight serotypes of human T-mycoplasmas are reported. The guanine plus cytosine contents, as measured by thermal denaturation and CsCl gradient centrifugation, are 27 to 28%, the latter method giving slightly lower values. The genome sizes are within the range of 4.1 × 108 to 4.8 × 108 daltons, which corresponds to the values found for members of the family Mycoplasmataceae.