Hybridization experiments were carried out between DNAs from more than 70 strains of Campylobacter spp. and related taxa and either 3H-labeled 23s rRNAs from reference strains belonging to Campylobacter fetus, Campylobacter concisus, Campylobacter sputorum, Campylobacter coli, and Campylobacter nitrofigilis, an unnamed Campylobacter sp. strain, and a Wolinella succinogenes strain or 3H-or 14C-labeled 23s rRNAs from 13 gram-negative reference strains. An immunotyping analysis of 130 antigens versus 34 antisera of campylobacters and related taxa was also performed. We found that all of the named campylobacters and related taxa belong to the same phylogenetic group, which we name rRNA superfamily VI and which is far removed from the gram-negative bacteria allocated to the five rRNA superfamilies sensu De Ley. There is a high degree of heterogeneity within this rRNA superfamily. Organisms belonging to rRNA superfamily VI should be reclassified in several genera. We propose that the emended genus Campylobacter should be limited to Campylo bacter fetus, Campylo bacter hy oin testinalis , Campylo bacter concisus, Campylo bacter m ucosalis , Campylobacter sputorum, Campylobacter jejuni, Campylobacter coli, Campylobacter lari, and "Campylobacter upsaliensis. " Wolinella curva and Wolinella recta are transferred to the genus Campylobacter as Campylobacter curvus comb. nov. and Campylobacter rectus comb. nov., respectively. Bacteroides gracilis and Bacteroides ureolyticus are generically misnamed and are closely related to the genus Campylobacter. Campylobacter nitrofigilis, Campylobacter cryaerophila, and an unnamed Campylobacter sp. strain constitute a new genus, for which the name Arcobacter is proposed; this genus contains two species, Arcobacter nitrofigilis comb. nov. (type species) and Arcobacter cryaerophilus comb. nov. Wolinellu succinogenes so far is the only species of the genus Wolinella. The genus Helicobacter is also emended; Campylobacter cinaedi and Campylobacter fennelliae are included in this genus as Helicobacter cinaedi comb. nov. and Helicobacter fennelliae comb. nov., respectively. The genus "Flexispira," with "Flexispira rappini" as the only species, is closely related to the genus Helicobacter. The free-living, sulfur-reducing campylobacters do not belong to any of these genera; they probably constitute a distinct genus within rRNA superfamily VI.At present, the genus Campylobacter consists of 13 welldefined species (40). Recently, two additional species, Campylobacter pylori and Campylobacter mustelae, were included in the new genus Helicobacter as Helicobacter pylori and Helicobacter mustelae, respectively (20). The clinical significance of all of these organisms was reviewed recently by Penner (40). A study of the taxonomic structure of the genus Campylobacter in which partial 16s rRNA sequence analysis was used revealed that the Campylobacter species can be divided into three major rRNA homology groups (58 It was the aim of this study to include all known campylobacters and possible relatives in...

We performed hybridizations between labeled rRNAs from seven representative members of the family Pasteurellaceae and from three other taxa on the one hand and DNAs from 53 strains known or presumed to belong to the Pasteurellaceae on the other hand. The members of the Pasteurellaceae are most closely related to members of the Enterobacteriaceae, the Vibrionaceae, the Aeromonadaceae, and the genus Alteromonas

The deoxyribonucleic acid (DNA):ribosomal ribonucleic acid (rRNA) hybridization technique was used to reveal the relationships and taxonomic positions of an additional 83 strains belonging to 43 saprophytic or pathogenic Pseudomonus species and 29 named and unnamed Pseudomonus-like strains. The DNA:rRNA hybrids were characterized by the following two parameters: (i) the temperature at which one-half of the hybrid was eluted and (ii) the percentage of rRNA binding (the amount of rRNA bound per 100 pg of filter-fixed DNA). We also used, for a limited number of strains, numerical analysis of carbon assimilation tests to delineate the finer taxonomic relationships of organisms. Of the 83 strains examined, 78 could be definitely assigned either to an rRNA branch or to an rRNA superfamily within the Proteobucteriu. Only 25 of our strains belong in the genus Pseudomonus sensu strict0 (our PseudomonusJluorescens rRNA branch). In general, about two-thirds of the named Pseudomonas species have been misclassified and are distributed over at least seven genera all through the Proteobacteriu. These organisms need to be reclassified and generically renamed according to their phylogenetic rglationships. However, more detailed phenotypic and genotypic studies are necessary before definite nomenclatural proposals can be made. A comprehensive list of the phylogenetic affiliations of the Pseudomonus species is included.From the original creation of Pseudomonas Migula 1894 until now, this genus has been a dumping ground for incompletely described, aerobic, polarly flagellated, gram-negat h e , rodlike bacteria. In the past and even today organisms isolated from a heterogeneous variety of ecological niches were and still are classified without sufficient grounds as new Pseudomonas species. One of the reasons for this situation is the incomplete generic definition.In the United States, the Berkeley group has reported in several papers (42,43,48) on the taxonomy of the genus Pseudomonas. The several hundred strains included in the important study of these workers involved only a relatively small number of species. Their new generic definition and subdivision of Pseudomonas was reflected in Bergey 's Manual of Determinative Bacteriology, 8th ed. (20). In an important reduction in the number of Pseudomonas species, more than 90% of the clinical, phytopathological, and saprophytic pseudomonads were relegated to four addenda to the genus Pseudomonas and were thus only marginally retained in this genus (20). Most of these organisms have no clear taxonomic status because their names were not retained on the Approved Lists of Bacterial Names (38, 46) nor were they on Validation Lists 17 to 23 (24-30). In Bergey's Manual of Systematic Bacteriology , Palleroni (41) listed 62 of these species in Section V of the genus Pseudomonas, although their natural relationships with other taxa are still largely unknown.We have shown in the past (11-15, 21, 45, 51, 54, 55) that the deoxyribonucleic acid (DNA):ribosomal ribonucleic acid (rRNA) hybridization...

'*C-labeled ribosomal ribonucleic acid (rRNA) was prepared from Azoto bacter chroococcum NCIB 8002, Azotobacter paspali 8A, Azomonas agilis NCIB 8636, Azomonas insignis WR 30, Beuerinckia indica NCIB 8712, and Azospirillum brasilense ATCC 29145. These rRNA's were hybridized under stringent conditions with filter-fixed deoxyribonucleic acid from a great variety of gram-negative bacteria. Each hybrid was described by: (i) the temperature at which 50% of the hybrid was denatured, and (ii) the percent rRNA binding (amount in micrograms of rRNA duplexed to 100 pg of deoxyribonucleic acid). These data were used to construct rRNA similarity maps. The following conclusions could be drawn concerning rRNA cistron similarities. (i) Bacterial genera with free-living, aerobic, nitrogen-fixing members are very diverse and belong to different rRNA superfamilies. The present family Azotobacteriaceae is not a biological unit, and its status as a family is highly questionable. (ii) Azotobacter chroococcum, Azoto bacter vinelandii, Azoto bacter beijerinckii, Azoto bacter paspali, Azoto bacter miscellum, Azotobacter armeniae, and Azotobacter nigricans belong in the genus Azotobacter. Any synonymy of these names remains to be determined. Azomonas agilis, Azomonas insignis, and Azomonas macrocytogenes constitute independent branches, which are about equidistant from Azotobacter and section I of Pseudomonas as presented in Bergey 's Manual of Determinative Bacteriology, 8th ed. Xanthomonas, Alteromonas vaga, and Alteromonas communis are located in the same rRNA superfamily. (iii) The genus Beijerinckia appears to be rather heterogeneous. Its closest relatives appear to be Xantho bacter autotrophicus, "Mycobacterium" flavum, "Pseudomonas" azotocolligans, "Pseudomonas" diminuta, the authentic rhodopseudomonads, and some other organisms. These organisms belong in the same rRNA superfamily as Azospirillum, Agrobacterium, Rhizo bium, Aceto bacter, Glucono bacter, and Zymomonas. (iv) Derxia belongs in still another rRNA superfamily , together with Chromobacterium, Janthinobacterium, the Pseudomonas acidovorans and Pseudomonas solanacearum groups, Alcalienes, and a few other taxa. (v) The following organisms were generically misnamed: "Azomonas insignis" ATCC 12523, "Mycobacterium" flavum 301, "Pseudomonas" azotocolligans ATCC 12417, "Pseudomonas" diminuta CCEB 513, and "Rhodopseudomonas" gelatinosa (all strains examined).Molecular biological methods, such as deoxyribonucleic acid (DNA)-DNA or DNA-ribosomal ribonucleic acid (rRNA) hybridizations, which directly compare bacterial genomes, have opened new perspectives for bacterial classification. Many bacterial genera are phylogenetic d y too far removed from each other to form stable DNA-DNA hybrids. DNA-DNA hybridizations are useful either within a genus, such as Agrobacterium (ZO), or between genera which have not diverged too much, such as in the Enterobacteriaceae (12; D. Izard, C. Ferragut, and H. Leclerc, in press). rRNA's are conservative molecules (25, 36, 43). There is a good corre...

A numerical analysis was performed on one-dimensional whole-cell protein electrophoretic fingerprints of 107 strains belonging to the basidiomycetous yeast genera Rhodosporidium and Rhodotorula. This technique allowed evaluation of taxonomic relationships at the species level. In particular for the anamorphic genus Rhodotorula, the electrophoretic groupings did not correspond in all cases with the existing species. Heterogeneity of strains within the anamorphic species Rhodotorula acheniorum, RtR aurantiaca, RtR araucariae, RtR foliorum, RtR glutinis, RtR graminis and Rt. minuta was found. There was a good correlation between the grouping obtained by numerical analysis of protein patterns, the mol% G + C content and the coenzyme Q type. Furthermore, the results obtained with the different techniques used suggest possible close interspecific and/or intergeneric relationships. Most Rhodotorula glutinis strains, including the type strain, and the type strain of Rhodotorula graminis were highly similar to strains of Rhodosporidium diobovatum. For other investigated strains of Rhodotorula glutinis, a high similarity was found with strains of Rhodosporidium kratochvilovae, Rs. sphaerocarpum, Rs. toruloides and Rhodotorula mucilaginosa, respectively. Most of the Rhodotorula graminis strains could not be differentiated from Rhodosporidium paludigenum strains.