- Volume 36, Issue 3, 1986

Strains of Legionella pneumophila serogroup 4 and Legionella bozemanii and three strains of a new species, for which the name Legionella israelensis is proposed, were isolated from an oxidation pond in Israel. L. israelensis exhibited the following biochemical reactions typical of legionellae: Growth on buffered cysteine-yeast extract agar but not on chocolate agar or on buffered yeast extract agar without cysteine; nitrate negative; urease negative; nonfermentative; catalase positive; and motile. It did not hydrolyze hippurate, autofluoresce, or produce a brown pigment on tyrosine-containing media, and it had weakly positive gelatinase activity. It had predominantly branched-chain cellular fatty acids, similar to those described for other legionellae, and had major amounts of ubiquinones with more than 10 isoprene units in their side chains. It could be distinguished from all previously described Legionella species and serogroups by using antisera in slide agglutination tests. As determined by the hydroxyapatite method at 60

Four strains of alkaliphilic methanogens (strains WeN1, WeN2, WeN3, and WeN4T [T = type strain]) previously enriched and isolated from sediments of four low-salt, high-pH (pH 8.3 to 9.3) lakes in the Wadi el Natrun of Egypt were further characterized. These organisms were H2-oxidizing, CO2-reducing, rod-shaped bacteria which grew best at high pH values (strains WeN1, WeN2, and WeN4T preferred pH 8.4 and grew at pH values up to 9.9; strain WeN3 grew best at pH 7.8 and grew at pH values up to 9.2). Each strain required sulfide as a sulfur source and was resistant to elevated concentrations (growth rates in the presence of 0.5% Na2S · 9H2O were one-third to one-half the maximum observed rates). The guanine-plus-cytosine content of the deoxyribonucleic acid of strain WeN4T was 57 mol%. A new species of methanogen, Methanobacterium alcaliphilum, is described; strain WeN4 (= DSM 3387) is the type strain.

A new species of Eubacterium, Eubacterium fossor, which was isolated from the pharynxes of normal horses and as a component of mixed flora from pyogenic diseases in horses, is described. This organism was found in oropharyngeal samples from seven normal horses, accounting for 22% of the anaerobic isolates, and was also isolated from pyogenic conditions (pleuropneumonia in two cases and parapharyngeal or tooth root abscesses in three cases) of horses. All strains were anaerobic, gram-positive rods which formed colonies that corroded agar. Noncorroding variants were not found. The addition of serum (5%, vol/vol) or Tween 80 (0.75%, vol/vol) was required to ensure optimum growth, which occurred in nutrient broth cultures (brain heart infusion or peptone-yeast extract medium). The fermentation products included major amounts of acetic and lactic acids. Strains of E. fossor sp. nov. had deoxyribonucleic acid guanine-plus-cytosine contents of 43 to 46 mol%. The type strain is strain NCTC 11919 (= Veterinary Pathology and Bacteriology Collection strain VPB 2127).

The name Psychrobacter immobilis is proposed for a group of chiefly psychrotrophic, aerobic, gram-negative, nonmotile, oxidase-positive coccobacilli commonly found associated with fish and processed meat and poultry products. The deoxyribonucleic acid base composition was found to vary from 44 to 46 mol% guanine plus cytosine. The properties of the psychrobacters and the moraxellae are very similar except that the optimum growth temperature for most psychrobacters is 20 to 25°C. Unlike the moraxellae, many psychrobacters are able to form acid aerobically from glucose and several other sugars. Some psychrobacters have an optimal growth temperature of 35 to 37°C and have been isolated from pathological specimens derived from humans and animals. Deoxyribonucleic acid samples from all psychrobacters were able to transform the same auxotroph of a competent strain to prototrophy, thus demonstrating that these organisms are members of a single genospecies. The psychrobacters appear to be distantly related to the moraxellae, and we suggest that strains of Psychrobacter immobilis be included in the family Neisseriaceae. The type strain (strain A351) has been deposited in the American Type Culture Collection as strain ATCC 43116.

Five strains of actinomyces isolated from dental plaque of cattle formed a homogeneous group on the basis of Gram staining, colonial and cellular morphology, fermentation reactions, acid end products of metabolism, sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of polypeptides, cell wall carbohydrates, and peptidoglycan and deoxyribonucleic acid mean base compositions. These organisms were closely related, as determined by deoxyribonucleic acid-deoxyribonucleic acid homology, which distinguishes them from strains of Actinomyces naeslundii, Actinomyces viscosus, Actinomyces denticolens, and Actinomyces howellii. A new taxon, Actinomyces slackii, is proposed for these isolates. The type strains of A. slackii is strain NCTC 11923.

The name Flexibacter maritimus is proposed for a group of 15 bacterial strains isolated from diseased red sea bream (Pagrus major), black sea bream (Acanthopagrus schlegeli), and rock bream (Oplegnathus fasciatus). These bacteria grew in cytophaga medium prepared with seawater but failed to grow in cytophaga medium supplemented with NaCl. The isolates were gram-negative, flexible rods which exhibited gliding motility on wet surfaces. They did not utilize agar, cellulose, or chitin. The mean guanine-plus-cytosine content of the deoxyribonucleic acids of eight selected strains was 31.8 ± 0.4 mol%. Strain R2 (= NCMB 2514) is designated the type strain of the new species.

The objective of this study was to investigate the antigenic profiles of Legionella pneumophila serogroups 1 to 6 and antigenic relatedness among individual serogroups. A reference precipitate pattern which had 71 anodic- and 6 cathodic-migrating antigens was established with a pooled antigen preparation of sonicated L. pneumophila cells of serogroups 1 to 6 against purified homologous rabbit antibody. Sixteen antigens made heat stable by boiling for 10 min were found, of which one could be demonstrated as being the common antigen of gram-negative bacteria and another could be shown as being the serogroup-specific antigen of L. pneumophila. Precipitin patterns similar in overall appearance and precipitin numbers were demonstrated for each serogroup by testing antigen preparations of individual serogroups against reference system antibody. Crossed-line experiments revealed < 5 non-cross-reacting antigens among serogroups, with resulting matching coefficients (ratio of the number of cross-reactive to total antigens) all above 0.91. The matching coefficients found when testing antigen preparations from L. pneumophila serogroups 7 and 8 were 0.93 and 0.99, respectively. By contrast, the matching coefficients of Tatlockia micdadei, Fluoribacter bozemanae, Fluoribacter dumoffii, and Fluoribacter gormanii was 0.39, 0.45, 0.39, and 0.41, respectively. Comparison of precipitate patterns and experimental results between the previously described monovalent L. pneumophila serogroup 1 system and the polyvalent crossed immunoelectrophoresis system with L. pneumophila serogroups 1 to 6 substantiated the antigenic homogencity of L. pneumophila and the significant difference in antigenic composition between this taxon and other members of the family Legionellaceae. In addition, reproducibility of the antigenic profile of L. pneumophila by crossed immunoelectrophoresis was demonstrated.

Hybridization experiments were carried out between 3H-labeled ribosomal ribonucleic acid from Bordetella bronchiseptica NCTC 452T (T = type strain), 14C-labeled ribosomal ribonucleic acid from Alcaligenes faecalis NCIB 8156T, or 14C-labeled ribosomal ribonucleic acid from Alcaligenes xylosoxidans subsp. denitrificans ATCC 15173T and deoxyribonucleic acids from various strains of Bordetella, Alcaligenes and other taxa. A numerical analysis of phenotypic features was also done. The genera Bordetella and Alcaligenes are very closely related, which warrants the proposal of a new family, the Alcaligenaceae.

Strains of facultative methylotroph Ancylobacter aquaticus were compared with other gram-negative, nonsporeforming, nonmotile, curved, and ring-forming bacteria. These bacteria utilize methanol and hydrogen, but not methane. The major cellular fatty acid is straight-chain unsaturated C18:1 acid. The major ubiquinone is Q-10, and Q-9 and Q-11 are present as minor components. Based on the above data, these methylotrophs are distinguished from the other similar curved and ring-forming bacteria: Spirosoma linguale, Flectobacillus major, F. marinus, and Runella slithyformis. The latter three genera do not utilize methanol, have low deoxyribonucleic acid base compositions, possess different cellular fatty acids, and have a menaquinone-7 system. Furthermore, F. marinus is clearly distinguished from F. major in cellular fatty acid composition.

β-Hemolytic group G streptococci from cows with mastitis and from dogs with different pathological conditions were characterized and named Streptococcus canis sp. nov. These animal group G strains were differentiated from Streptococcus dysgalactiae (group G strains of human origin, as well as group L strains and certain animal and human group C strains) by simple physiological and biochemical tests. Deoxyribonucleic acid-deoxyribonucleic acid hybridization showed that the S. canis strains differed from S. dysgalactiae, Streptococcus pyogenes, Streptococcus equi, and Streptococcus salivarius. These organisms contain a rare cell wall peptidoglycan type, namely, Lys-Thr-Gly. The specific epithet of S. canis, which has been in use for many years in veterinary textbooks to designate group G strains isolated from dogs, was chosen for this proposed new species because it comprises animal but not human group G streptococci. The type strain is strain STR-T1 (= DSM 20715).

Southern blot hybridization of digested deoxyribonucleic acids (DNAs) of Mycoplasma genitalium, M. pneumoniae, and M. gallisepticum with probes made of total DNA of any one of these mycoplasmas revealed hybridization bands additional to those containing ribosomal ribonucleic acid (rRNA) gene sequences, which were identifiable by specific rRNA gene probes. The number and intensity of these additional bands were most pronounced with the M. genitalium-M. pneumoniae pair, which shares major antigenic determinants. Hybridization with M. pulmonis and Spiroplasma citri DNAs as probes revealed only the rRNA gene bands in digested DNAs of M. genitalium, M. pneumoniae, and M. gallisepticum. DNA-DNA hybridization tests in solution, with M. genitalium and M. pneumoniae DNA as probes, corroborated the Southern blotting data by showing the highest homology values between M. genitalium and M. pneumoniae (6.5 to 8.1%), lower with M. gallisepticum (3.5 to 4.0%), and lowest with S. citri (0.5 to 0.9%). The new hybridization approach provides visual evidence for genetic relatedness between M. genitalium and M. pneumoniae and may facilitate the identification and cloning of genomic DNA segments carrying genes shared by two or more mycoplasmas.

The lobster pathogen Aerococcus viridans and other gram-positive, marine A. viridans-like cocci were examined morphologically, biochemically, and genetically. Morphologically, the lobster pathogenic strains were unique in their tetrad-forming capacity. Because of intragroup fermentative variations among the lobster-pathogenic strains and values of deoxyribonucleic acid (DNA) base composition overlapping those of the other cocci, the lobster pathogens did not stand out as a separate group based on these data. According to the DNA-DNA hybridization studies, however, the lobster-pathogenic strains were very closely related (80 to 100% homology) and could be easily separated from the remaining strains. All the cocci had extraordinarily small genomes ranging from 0.57 x 109 to 1.01 x 109 daltons.

Twelve isolates of thermophilic, acidophilic, cellulolytic bacteria were obtained from three different primary enrichment cultures from acidic hot springs at Yellowstone National Park, Wyo. The three isolates which had the highest cellulolytic activity, as shown by the diameter of clearing zones surrounding colonies on cellulose agar plates, were selected for intensive study. All were gram-variable, nonsporulating aerobic rods which formed no pigment. They grew at 37 to 65°C, with optimum growth at 55°C. The pH range for growth was 3.5 to 7, with an optimum pH of 5. The guanine-plus-cytosine content of the deoxyribonucleic acid was 60.7 ± 0.6 mol%. The organisms are resistant to penicillin G at 100 μg/ml. They share several important features with Thermus strains, namely heterotrophic, aerobic, and thermophilic mode of growth; morphological features; sensitivity to lysozyme; and presence of catalase. They differ in other important aspects, such as the pattern of carbon sources utilized for growth, the pH and temperature profiles of growth, the pattern of sensitivity to antibiotics, the guanine-plus-cytosine content of DNA, the composition of amino acids in the cell walls, and the structure of the cell walls. Thermus species are very sensitive to penicillin G, whereas our strains are resistant. Our strains also are different, in important respects, from the genus Thermomicrobium. Therefore, we designate the organism Acidothermus cellulolyticus gen. nov., sp. nov., of which the type strain is our strain 11B, ATCC 43068.

For a detailed pheno- and genotypic characterization of the genus Thermus, the following seven representative strains were analyzed: Three extremely thermophilic strains (optimal temperature for growth, 65 to 75°C), Thermus aquaticus DSM 625, “Thermus flavus” DSM 674, and “Thermus thermophilus” DSM 579; and four moderately thermophilic strains (optimal temperature for growth 55 to 60°C), Thermus ruber DSM 1279 and three new isolates (strains H1, H2, and H3) from sewage. All of these strains exhibited isobranched pentadecanoic and heptadecanoic acids as principal components of their fatty acids, possessed unsaturated menaquinones with eight isoprene units, and had deoxyribonucleic acid guanine-plus-cytosine contents of 59 to 65.5 mol%, and their cell walls contained a murein structure of the A3β variation (interpeptide bridge, Gly2). The clustering of the organisms into extremely and moderately thermophilic strains correlated well with molecular properties, such as the absorption spectra of their pigments and the ratio of pentadecanoic acid to heptadecanoic acid. This grouping was confirmed by the results of 16S ribosomal ribonucleic acid cataloging and deoxyribonucleic acid-deoxyribonucleic acid hybridization. Our data confirm current proposals for classification of the genus Thermus into the following two distinct species: T. aquaticus for the extremely thermophilic strains and T. ruber for the moderately thermophilic strains. Phylogenetically, representatives of the genus Thermus show a remote but significant relationship to Deinococcus species (similarity coefficients, 0.22 to 0.29); members of these two genera share a common peptidoglycan type.

A new subspecies, Xenorhabdus nematophilus subsp. beddingii, is described to accommodate the bacterial symbionts of two undescribed species of Steinernema, which are entomopathogenic nematodes. Strains of this subspecies are gram-negative, facultatively anaerobic, peritrichously flagellated rods. They occur in two forms; one of these forms is positive for pigmentation (brown), adsorption of bromothymol blue, and production of antimicrobial compounds, whereas the other form is negative for these characteristics. They are pathogenic when injected into insects. Like other X. nematophilus strains, they are negative for catalase and nitrate reductase. All strains produced acid from glucose (no gas), dextrin, fructose, maltose, mannose, and trehalose, and some produced acid from glycerol, ribose, or salicin. The new subspecies is distinguished from the other three subspecies of X. nematophilus by being positive for phosphatase and esculin hydrolysis. The type strain is strain Q58/1 and has been deposited in the University of Queensland Microbiology Collection as strain UQB 2871.

A deoxyribonucleic acid relatedness study of 13 Mycobacterium chelonae strains indicated that M. chelonae subsp. chelonae and M. chelonae subsp. abscessus are two different genomic species, both distinct from Mycobacterium fortuitum and “Mycobacterium peregrinum.” One strain of M. chelonae constitutes a third genomic species. The type strain of M. fortuitum and the reference strain of “M. peregrinum” (strain ATCC 14467) belong to two different genomic groups.

The placement of Bacteroides praeacutus (Tissier) in the genus Bacteroides is controversial. Recent biochemical and chemical data clearly demonstrate that B. praeacutus is sufficiently unrelated to the type species of Bacteroides, B. fragilis (Castellani and Chalmers), that it should not be retained within this genus. It is therefore formally proposed that B. praeacutus be removed from the genus Bacteroides and reclassified in a new genus, Tissierella, as T. praeacuta comb. nov. The type strain of T. praeacuta is ATCC 25539 (NCTC 11158).

Lists of abbreviations for genus names of bacteria and codes for commonly occurring parts of genus names are expanded to accommodate 135 new entries which are names that have been validly published since the publication of the Approved Lists of Bacterial Names in 1980. Also, 61 abbreviations of yeast genus names are included for the first time.