Deoxyribonucleic Acid Homologies Among Species of the Genus Neisseria

Eleven aerobic species of Neisseria, a Mima sp., and a Herellea sp. were tested for deoxyribonucleic acid (DNA) homology in direct hybridization experiments. DNA labeled with either (14)C or (32)P was prepared from five species of Neisseria. Unlabeled DNA from the various microorganisms was immobilized on membrane filters, which, after pretreatment, were incubated with labeled DNA (4,000 counts per min per filter) for 14 hr at 67 C. The measure of relatedness was expressed as the relative percentage of direct binding compared to that obtained with homologous DNA. All serological types of N. meningitidis, including the newly proposed types, were homologous to the standard strain of N. meningitidis with one possible exception, type Z. The genus Neisseria is heterogeneous in nature, forming at least three distinct groups: first, N. meningitidis and N. gonorrhoeae; second, N. perflava, N. subflava, N. sicca, N. flavescens, and N. flava; third, N. catarrhalis and N. caviae. Mima and Herellea species show no significant homology with the Neisseria.