Taxonomy of the Neisseriae: Deoxyribonucleic Acid Base Composition, Interspecific Transformation, and Deoxyribonucleic Acid Hybridization

Abstract

Deoxyribonucleic acid (DNA) base composition, intergenic transformation efficiency, and DNA hybridization were used to determine the relatedness of a variety of established or proposed species of Neisseria and Branhamella. These studies indicated that these bacteria form three genetic groupings. Group I, comprised of N. meningitidis, N. gonorrhoeae, N. subflava, N. flava, N. perflava, N. sicca, N. mucosa, N. cinerea, N. flavescens, N. lactamica, N. elongata, N. canis, and N. denitrificans, was characterized by DNA base compositions ranging between 49.3 and 55.6 mol% guanine plus cytosine. Group II, comprised of N. cuniculi, N. caviae, and N. ovis, was characterized by DNA base compositions ranging between 45.3 and 47.3 mol% guanine plus cytosine. Group III, comprised of one species, B. catarrhalis, was characterized by DNA base compositions between 41 and 42 mol% guanine plus cytosine. Transformation and DNA hybridization results revealed that members of each group, with few exceptions, exhibited high DNA homology with other members of the same group but most often distinctly lower levels of homology with members of a different group. These data suggest that N. ovis, N. caviae, and N. cuniculi may be significantly different from other neisseriae and from branhamellae to warrant their separation in a distinct genus.