Nucleic Acid Homologies of Selected Bacteria, L Forms, and Mycoplasma Species

Abstract

Rogul , M. (Walter Reed Army Institute of Research, Washington, D.C.), Z. A. McGee, R. G. Wittler, and Stanley Falkow . Nucleic acid homologies of selected bacteria, L forms, and Mycoplasma species. J. Bacteriol. 90: 1200–1204. 1965.—The molar per cent of guanine plus cytosine (G + C) in the deoxyribonucleic acids (DNA) of Proteus mirabilis , strain 9, and its stable L form was determined by thermal denaturation and found to be approximately 39.5% G + C. The DNA homologies of this bacterium and its L form were estimated by the agar-column technique and were equivalent in their abilities to anneal and form specific duplexes. The next series of comparisons were performed between two Mycoplasma species and their often suggested bacterial parent. The G + C ratios of M. gallisepticum (32.7%), M. gallinarum (28.1%), and Haemophilus gallinarum (41.9%) varied to a high degree. In the homologous system, the denatured DNA of H. gallinarum trapped in agar bound approximately 40% of its sheared, denatured, and H 3 -labeled DNA. In comparison, the nucleic acids of M. gallinarum and M. gallisepticum were incapable of binding the labeled DNA of H. gallinarum . These findings provided evidence that the two strains of Mycoplasma were not derived from H. gallinarum .