RELATEDNESS OF 3 SPECIES OF FALSE NEISSERIAE, NEISSERIA-CAVIAE, NEISSERIA-CUNICULI, AND NEISSERIA-OVIS, BY DNA-DNA HYBRIDIZATIONS AND FATTY-ACID ANALYSIS

DNA-DNA hybridization was used to determine the levels of genomic rela tedness of the three species of ''false neisseriae,'' Neisseria caviae , Neisseria cuniculi, and Neisseria ovis. The reference strains of the se species exhibited high levels of intraspecies relatedness (93 to 10 0% for N. caviae, 79 to 100% for N. cuniculi, and 68 to 100% for N. ov is) but low levels of interspecific relatedness (less than 34%) to eac h other and to various species belonging to the beta subclass of the P roteobacteria (Kingella kingae, Neisseria gonorrhoeae, Neisseria menin gitidis, and Oligella urethralis) or to the gamma subclass (Branhamell a catarrhalis, Kingella indologenes, Moraxella atlantae, Moraxella bov is, Moraxella lacunata subsp. lacunata, Moraxella lacunata subsp. liqu efaciens, Moraxella nonliquefaciens, Moraxella osloensis, and Moraxell a phenylpyruvica). However, the levels of DNA-DNA hybridization for th e three species of ''false neisseriae'' were significantly higher with the species belonging to the gamma subclass (average, 13.7%) than wit h the species belonging to the beta subclass (average, 4.5%). These da ta suggest that N. caviae, N. cuniculi, and N. ovis are three separate genomic species in the gamma subclass. An ascendant hierarchical clas sification based only on fatty acid profiles distinguished four main c lasses containing (i) most of the ''classical moraxellae,'' the ''fals e neisseriae,'' and B. catarrhalis, (ii) only Acinetobacter spp., (iii ) M. nonliquefaciens and ''misnamed moraxellae'' (M. atlantae, M. oslo ensis, and M. phenylpyruvica), and (iv) the ''true neisseriae,'' the t hree Kingella species, and O. urethralis. Fatty acids that distinguish these four classes were identified. The fatty acid profiles of the tw o strains of Psychrobacter immobilis which we studied are not very sim ilar to the profiles of the other taxa. Our results support the hypoth esis that the three species of ''false neisseriae,'' B. catarrhalis, t he ''classical moraxellae,'' and Acinetobacter spp. should be included in the same family.