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

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 iving slightly lower values. The corresponds to the values found for members of the family Mycoplasmataceae. genome sizes are within the range of 4.1 X 10 4 to 4.8 X lo8 daltons, which