John L. Johnson

Serpulina pilosicoli sp. nov., the agent of porcine intestinal spirochetosis.

Phenotypic and genetic traits of porcine intestinal spirochete strain P43/6/78T (= ATCC 51139T) (T = type strain), which is pathogenic and weakly beta-hemolytic, were determined in order to confirm the taxonomic position of this organism and its relationships to previously described species of intestinal spirochetes. In BHIS broth, P43/6/78T cells had a doubling time of 1 to 2 h and grew to a maximum cell density of 2 x 10(9) cells per ml at 37 to 42 degrees C. They hydrolyzed hippurate, utilized D-glucose, D-fructose, sucrose, D-trehalose, D-galactose, D-mannose, maltose, N-acetyl-D-glucosamine, D-glucosamine, pyruvate, L-fucose, D-cellobiose, and D-ribose as growth substrates, and produced acetate, butyrate, ethanol, H2, and CO2 as metabolic products. They consumed substrate amounts of oxygen and had a G+C content (24.6 mol%) similar to that of Serpulina hyodysenteriae B78T (25.9 mol%). Phenotypic traits that could be used to distinguish strain P43/6/78T from S. hyodysenteriae and Serpulina innocens included its ultrastructural appearance (each strain P43/6/78T cell had 8 or 10 periplasmic flagella, with 4 or 5 flagella inserted at each end, and the cells were thinner and shorter and had more pointed ends than S. hyodysenteriae and S. innocens cells), its faster growth rate in liquid media, its hydrolysis of hippurate, its lack of beta-glucosidase activity, and its metabolism of D-ribose. DNA-DNA relative reassociation experiments in which the S1 nuclease method was used revealed that P43/6/78T was related to, but was genetically distinct from, both S. hyodysenteriae B78T (level of sequence homology, 25 to 32%) and S. innocens B256T (level of sequence homology, 24 to 25%). These and previous results indicate that intestinal spirochete strain P43/6/78T represents a distinct Serpulina species. Therefore, we propose that strain P43/6/78 should be designated as the type strain of a new species, Serpulina pilosicoli.

Use of Nucleic-Acid Homologies in the Taxonomy of Anaerobic Bacteria

Nucleic acid homology studies are providing a common base for establishing bacterial groups. Few phenotypic characteristics have consistently correlated with homology data among the various groups of organisms that we have investigated. However, there are correlations that are specific for a given group of bacteria such that nucleic-acid homology data can be used to select those phenotypic properties that will be most useful for identification and taxonomic purposes.

Deoxyribonucleic Acid Homologies Among Strains of Bacillus sphaericus

The genetic relatedness of 62 strains of Bacillus sphaericus, 4 strains of B. pasteurii, 6 strains of B. brevis, and 1 strain each of B. globisporus and B. aminovorans was examined by deoxyribonucleic acid (DNA) homology. Five homology groups were identified, and they contained all but 12 of the B. sphaericus strains. Intergroup homologies ranged from about 20 to 40% except for groups III and IV, which had 50 to 60% intergroup homology. Although a few strains within some groups had 63 to 69% homology to the reference strain, most strains were in the 70 to 90% range. Homology group I contained the type of strain of B. sphaericus, ATCC 14577, and three other strains. Homology group II was subdivided into groups IIA and IIB, the former containing all of the strains found to be pathogenic for mosquito larvae. Although none of the physiological characteristics or combination of characteristics examined allowed the complete differentiation of strains into the appropriate homology groups, the strains of group I could be distinguished from those of group IIA-IIB. The strains of group IIA could be distinguished from all others by mosquito pathogenicity. The B. pasteurii strains formed a distinct homology group, although the guanine plus cystosine contents of their DNAs fell within the range of 34 to 37 mol% found for the 45 strains of B. sphaericus examined for this property. The B. brevis strains possessed a higher guanine plus cystosine content, and their DNAs were unrelated to the DNAs of the B. sphaericus reference strains tested.

Emendation of Bacteroidaceae and Butyrivibrio and Descriptions of Desulfomonas gen. nov. and Ten New Species in the Genera Desulfomonas, Butyrivibrio, Eubacterium, Clostridium, and Ruminococcus

The family Bacteroidaceae is emended to include bacteria that are monotrichous or lophotrichous. The genus Butyrivibrio is emended to include lophotrichous bacteria. Desulfomonas, a new genus of nonmotile, nonsporeforming, gram-negative, anaerobic, sulfate-reducing rods, and 10 new species of anaerobes, Desulfomonas pigra, Butyrivibrio crossotus, Ruminococcus gnavus, R. lactaris, R. obeum, Eubacterium dolichum, E. hadrum, E. ramulus, E. siraeum, and Clostridium leptum, are described. These species have been isolated from human intestinal contents or from human feces. The type strains of these species are ATCC 29098, 29175, 29149, 29176, 29174, 29143, 29173, 29099, 29066, and 29065, respectively.

Phylogenetic study of the genus Campylobacter

The phylogenetic relationships of all species in the genus Campylobacter, Wolinella succinogenes, and other gram-negative bacteria were determined by comparison of partial 16S ribosomal ribonucleic acid sequences. The results of this study indicate that species now recognized in the genus Campylobacter make up three separate ribosomal ribonucleic acid sequence homology groups. Homology group I contains the following true Campylobacter species: Campylobacter fetus (type species), Campylobacter coli, Campylobacter jejuni, Campylobacter laridis, Campylobacter hyointestinalis, Campylobacter concisus, Campylobacter mucosalis, Campylobacter sputorum, and “Campylobacter upsaliensis” (CNW strains). “Campylobacter cinaedi,” “Campylobacter fennelliae,” Campylobacter pylori, and W. succinogenes constitute homology group II. Homology group III contains Campylobacter cryaerophila and Campylobacter nitrofigilis. We consider the three homology groups to represent separate genera. However, at present, easily determinable phenotypic characteristics needed to clearly differentiate them are not apparent. The three homology groups are only distantly related to representatives of the alpha, beta, and gamma branches of the purple bacteria, indicating that these bacteria do not belong to any previously defined branch of this phylum.

Deoxyribonucleic acid similarities among Pseudomonas species

Deoxyribonucleic acid similarity experiments in which the S1 nuclease methodology was used were performed on strains of Pseudomonas species, including some that had not been previously subjected to similarity measurements. The results obtained with this technique confirmed and expanded previous observations on the low levels of deoxyribonucleic acid similarity among species of the genus as determined by membrane competition experiments. A general discussion of the results and nomenclatural status of some of the species is included.

Description of Bacteroides loescheii sp. nov. and Emendation of the Descriptions of Bacteroides melaninogenicus (Oliver and Wherry) Roy and Kelly 1939 and Bacteroides denticola Shah and Collins 1981

Bacteroides loescheii, a new species from periodontal pockets and superficially cleaned tooth surfaces coronal to gingival margins and from various types of human infections, is described. Strains of B. loescheii are obligately anaerobic, gram-negative, usually pigmenting, nonmotile, nonsporeforming rods that do not grow well in 10% bile and that ferment carbohydrates. These strains previously were identified as Bacteroides melaninogenicus or Bacteroides oralis, but they have no deoxyribonucleic acid homology with the type strain of either of these two species. The type strain of B. loescheii is ATCC 15930. The descriptions of B. melaninogenicus and Bacteroides denticola are emended.

Reinstatement of Species Rank for Bacteroides fragilis, B. ovatus, B. distasonis, B. thetaiotaomicron, and B. vulgatus: Designation of Neotype Strains for Bacteroides fragilis (Veillon and Zuber) Castellani and Chalmers and Bacteroides thetaiotaomicron (Distaso) Castellani and Chalmers

The organisms currently recognized as subspecies of Bacteroides fragilis have been shown to be genetically distinct. Species rank is therefore restored to these organisms, and type or neotype strains have been selected for the five species described. ATCC 25285 (= NCTC 9343) is designated the neotype strain of Bacteroides fragilis (Veillon and Zuber) Castellani and Chalmers; ATCC 29184 (= strain Werner E50 = NCTC 10582) is designated the neotype strain of Bacteroides thetaiotaomicron (Distaso) Castellani and Chalmers; ATCC 8503 is designated the type strain of Bacteroides distasonis Eggerth and Gagnon; ATCC 8483 is designated the type strain of Bacteroides ovatus Eggerth and Gagnon; and ATCC 8482 is designated the type strain of Bacteroides vulgatus Eggerth and Gagnon. Characteristics of these strains are presented.

Lactobacillus uli sp. nov. and Lactobacillus rimae sp. nov. from the Human Gingival Crevice and Emended Descriptions of Lactobacillus minutus and Streptococcus parvulus

Lactobacillus uli sp. nov. and Lactobacillus rimae sp. nov. are described. These organisms are short, gram-positive, strictly anaerobic, rod-shaped bacteria that have DNA G+C contents of 53 and 45 mol%, respectively, produce major amounts of lactic acid, and have been isolated from human gingival crevices and periodontal pockets. The major cellular fatty acid derivatives for both species are C18:1 cis-9 fatty acid methyl ester and C18:1 cis-9 dimethylacetyl. The type strain of L. uli is strain VPI D76D-27C (= ATCC 49627), and the type strain of L. rimae is strain D140H-11A (= ATCC 49626). Emended descriptions of Lactobacillus minutus (based on selected strains) and Streptococcus parvulus (based on many additional strains) also are given.

Treponema socranskii sp. nov., Treponema socranskii subsp. socranskii subsp. nov., Treponema socranskii subsp. buccale subsp. nov., and Treponema socranskii subsp. paredis subsp. nov. Isolated from the Human Periodontia

A new species, Treponema socranskii, and three new subspecies, T. socranskii subsp. socranskii, T. socranskii subsp. buccale, and T. socranskii subsp. paredis, which were isolated from supragingival and subgingival samples from patients with periodontitis and from patients with experimental gingivitis, are described. These organisms are treponemes that ferment carbohydrates and require rumen fluid or shortchain volatile fatty acids for growth. Fermentable carbohydrates are required as an energy source. The major products of fermentation are acetic, lactic, and succinic acids. Trace amounts of formic acid are also produced. The level of deoxyribonucleic acid-deoxyribonucleic acid homology within each subspecies is greater than 80%, whereas the level of homology between subspecies is about 60%. The average guanineplus-cytosine content of the deoxyribonucleic acid is 51 ± 1 mol%. The type strain of T. socranskii is strain ATCC 35536 (= VPI DR56BRIII6); the type strain of T. socranskii subsp. buccale is strain ATCC 35534 (= VPI D2B8); and the type strain T. socranskii subsp. paredis is strain ATCC 35535 (= VPI D46CPE1).