Common Deoxyribonucleic Acid Sequences in Mycoplasma genitalium and Mycoplasma pneumoniae Genomes

Abstract

Southern blot hybridization of digested deoxyribonucleic acids (DNAs) of Mycoplasma genitalium, M. pneumoniae, and M. gallisepticum with probes made of total DNA of any one of these mycoplasmas revealed hybridization bands additional to those containing ribosomal ribonucleic acid (rRNA) gene sequences, which were identifiable by specific rRNA gene probes. The number and intensity of these additional bands were most pronounced with the M. genitalium-M. pneumoniae pair, which shares major antigenic determinants. Hybridization with M. pulmonis and Spiroplasma citri DNAs as probes revealed only the rRNA gene bands in digested DNAs of M. genitalium, M. pneumoniae, and M. gallisepticum. DNA-DNA hybridization tests in solution, with M. genitalium and M. pneumoniae DNA as probes, corroborated the Southern blotting data by showing the highest homology values between M. genitalium and M. pneumoniae (6.5 to 8.1%), lower with M. gallisepticum (3.5 to 4.0%), and lowest with S. citri (0.5 to 0.9%). The new hybridization approach provides visual evidence for genetic relatedness between M. genitalium and M. pneumoniae and may facilitate the identification and cloning of genomic DNA segments carrying genes shared by two or more mycoplasmas.