scholarly journals A taxonomic study of the Spirillum lipoferum group, with descriptions of a new genus, Azospirillum gen. nov. and two species, Azospirillum lipoferum (Beijerinck) comb. nov. and Azospirillum brasilense sp. nov.

1978 ◽  
Vol 24 (8) ◽  
pp. 967-980 ◽  
Author(s):  
Jeffrey J. Tarrand ◽  
Noel R. Krieg ◽  
Johanna Döbereiner
Keyword(s):  
Thermal Denaturation ◽  
New Genus ◽  
Free Medium ◽  
Dna Homology ◽  
Azospirillum Lipoferum ◽  
Dna Base Composition ◽  
Homology Groups ◽  
Group I ◽  
Dna Base ◽  
Group Ii

Sixty-one strains of the root-associated nitrogen fixer Spirillum lipoferum exhibited a similar morphology in peptone–succinate salts medium: vibrioid cells having a diameter of 1.0 μm. When grown in broth the cells had a single polar flagellum, but when grown on agar at 30 °C lateral flagella of shorter wavelength were also formed. The DNA base composition was 69–71 mol % guanine + cytosine when determined by thermal denaturation. DNA homology experiments indicated the occurrence of two distinct but related homology groups: 46 strains were in group I and 15 strains were in group II. Group II strains were distinguished by their ability to use glucose as a sole carbon source for growth in nitrogen-free medium, by their production of an acidic reaction in a peptone-based glucose medium, by their requirement for biotin, and by their formation of wider, longer, S-shaped or helical cells in semisolid nitrogen-free malate medium. The results indicate that two species exist, and on the basis of their characteristics it is proposed that they be assigned to a new genus, Azospirillum. Strains belonging to group II are named A.lipoferum (Beijerinck) comb, nov., while those belonging to group I are named A.brasilense sp. nov. Strain Sp 59b (ATCC 29707) is proposed as the neotype strain for A. lipoferum, and strain Sp 7 (ATCC 29145) is proposed as the type strain for A. brasilense.

DNA base composition of Neisseria, Moraxella, and Acinetobacter, as determined by measurement of buoyant density in CsCl gradients

1969 ◽  
Vol 15 (4) ◽  
pp. 335-338 ◽  
Author(s):  
K. Bøvre ◽  
M. Fiandt ◽  
W. Szybalski
Keyword(s):  
Buoyant Density ◽  
Mutual Transformation ◽  
Supporting Evidence ◽  
Dna Base Composition ◽  
Group I ◽  
Dna Base ◽  
Wide Range ◽  
Additional Support ◽  
Neisseria Flavescens

The guanine + cytosine contents (%(G + C)) of DNAs from 75 strains of asaccharolytic Neisseria, Moraxella, and Acinetobacter have been determined by measuring their buoyant densities in the CsCl gradient. The main purpose was to provide supporting evidence for taxonomic conclusions based on assay of genetic transformation to streptomycin resistance among the same strains and species.Three groups of neisseriae can be recognized, both by determination of %(G + C) and by transformation assay: (i) Neisseria flavescens and N. cinerea (46.5–49%), (ii) N. catarrhalis (41–42.5%), and (iii) N. caviae and N. ovis (44.5–45%). There is no transformation compatibility between group (i) and the other groups, whereas groups (ii) and (iii) show mutual transformation interactions. N. catarrhalis, N. caviae, and N. ovis, therefore, can also be considered as one group of nonpigmented, asaccharolytic neisseriae.Four groups of moraxellae can be distinguished: (i) Moraxella nonliquefaciens, M. lacunata, M. liquefaciens, and M. bovis (40–43%), (ii) M. osloensis (43–43.5%), (iii) M. phenylpyrouvica (43–43.5%), and (iv) M. kingii (44.5%). Although groups (ii) and (iii) are identical in terms of %(G + C), they exhibit low transformation compatibility, of the same order as between groups (i) and (ii). The distinctly higher G + C content of M. kingii DNA is consistent with its lack of transformation compatibility with other moraxellae.The similar %(G + C) range for the moraxellae and the nonpigmented, asaccharolytic neisseriae is consistent with the finding of some transformation compatibility between most of these organisms (except M. kingii) and provides additional support for the assumption that they are closely related.The Acinetobacter strains studied exhibit a wide range of G + C contents (38–45%) and hardly any transformation compatibility with neisseriae and moraxellae, even if some of them have matching %(G + C).It can be concluded that determination of the G + C contents of bacterial DNAs provides useful supplementary taxonomic data, but has only limited value as a sole taxonomic criterion.

Genetic diversity in Bradyrhizobium japonicum Jordan 1982 and a proposal for Bradyrhizobium elkanii sp.nov.

1992 ◽  
Vol 38 (6) ◽  
pp. 501-505 ◽  
Author(s):  
L. D. Kuykendall ◽  
B. Saxena ◽  
T. E. Devine ◽  
S. E. Udell
Keyword(s):  
Type Strain ◽  
Homology Group ◽  
Dna Homology ◽  
Homology Groups ◽  
Hybridization Probes ◽  
Bradyrhizobium Elkanii ◽  
Group Ii ◽  
A New Species ◽  
Strain Usda ◽  
Soybean Nodulation

Fourteen randomly selected clones from cosmid libraries of Bradyrhizobium were used as hybridization probes in Southern blot analysis. Seven of the probes used were from strain USDA 83, a group II strain, and the other seven were from strain I-110, a group Ia strain. The 30 strains examined included 9 strains of Rj4-incompatible soybean bradyrhizobia. Considerable polynucleotide sequence dissimilarity between DNA homology groups was evidenced by striking differences in the number of hybridizing bands, except where the probe carried repetitive DNA. Predictable, simple restriction fragment length polymorphism differences were observed only within DNA homology groups. The previous description that 8 of 9 Rj4-incompatible strains belonged to DNA homology group II was verified. The new data, together with many previously documented differences, make it clear that the DNA homology group II organisms should be classified as a new species, for which the name Bradyrhizobium elkanii is proposed, and strain USDA 76 is designated the type strain. The ATCC number for the type strain is 49852. Key words: DNA:DNA hybridization, soybean, nodulation, bacteria, symbiosis, nitrogen fixation, host compatibility.

scholarly journals Spiroplasma insolitum sp. nov., a New Species of Group I Spiroplasma with an Unusual DNA Base Composition

1993 ◽  
Vol 43 (2) ◽  
pp. 272-277 ◽  
Author(s):  
K. J. Hackett ◽  
R. F. Whitcomb ◽  
J. G. Tully ◽  
D. L. Rose ◽  
P. Carle ◽  
...  
Keyword(s):  
New Species ◽  
Base Composition ◽  
Dna Base Composition ◽  
Group I ◽  
Dna Base ◽  
A New Species

DNA base composition of filarial nematodes

Parasitology ◽  
1988 ◽  
Vol 97 (1) ◽  
pp. 75-79 ◽  
Author(s):  
N. Rothstein ◽  
T. J. Stoller ◽  
T. V. Rajan
Keyword(s):  
Base Composition ◽  
Thermal Denaturation ◽  
Gc Content ◽  
Direct Analysis ◽  
Molar Content ◽  
Free Living ◽  
Dna Base Composition ◽  
Base Content ◽  
Dna Base ◽  
Filarial Nematodes

SUMMARYWe have determined the molar content of guanine + cytosine (GC content) of DNA of the filarial nematode (Brugia malayi, Brugia pahangi and Dirofilaria imitis) and of the free-living soil nematodes Caenorhabditis elegans and have analysed the DNA for the presence of methylcytosine. Two independent methods, thermal denaturation and direct analysis of base content by HPLC following enzymatic hydrolysis, reveal that the GC content of filarial nematodes is 26–28%. We have been unable to find methylcytosine in the DNA of B. malayi.

DNA homology among diverse spiroplasma strains representing several serological groups

1980 ◽  
Vol 26 (11) ◽  
pp. 1356-1363 ◽  
Author(s):  
I.-M. Lee ◽  
R. E. Davis
Keyword(s):  
Dna Sequence ◽  
Sequence Homology ◽  
Dna Homology ◽  
Group Iii ◽  
Molecular Weights ◽  
Group I ◽  
Group Ii ◽  
Corn Stunt Spiroplasma ◽  
Type Strains ◽  
Tulip Tree

Deoxyribonucleic acid (DNA) homology among 10 strains of spiroplasma associated with plants and insects was assessed by analysis of DNA–DNA hybrids with single strand specific S1 nuclease. Based on DNA homology, the spiroplasmas could be divided into three genetically distinct groups (designated I, II, and III), corresponding to three separate serogroups described previously. DNA sequence homology between the three groups was ≤5%. Based on DNA homology, group I could be divided into three subgroups (A, B, and C) that corresponded to three serological subgroups of serogroup I. Subgroup A contained Spiroplasma citri strains Maroc R8A2 and C 189; subgroup B contained strains AS 576 from honey bee and G 1 from flowers; subgroup C contained corn stunt spiroplasma strains 1-747 and PU 8-17. There was 27–54% DNA sequence homology among these three subgroups. Group II contained strains 23-6 and 27-31 isolated from flowers of tulip tree (Liriodendron tulipifera L.). Group III contained strains SR 3 and SR 9, other isolates from flowers of tulip tree. Based on thermal denaturation, guanine plus cytosine contents of DNA from five type strains representing all groups and subgroups were estimated to be close to 26 mol% for group I strains, close to 25 mol% for group II strains, and close to 29 mol% for group III strains. The genome molecular weights of these five type strains were all estimated to be about 109.

The evolution of Antarctic yeasts: DNA base composition and DNA–DNA homology

1982 ◽  
Vol 28 (4) ◽  
pp. 406-413 ◽  
Author(s):  
Siavash Baharaeen ◽  
John A. Bantle ◽  
Helen S. Vishniac
Keyword(s):  
Base Composition ◽  
Common Ancestor ◽  
Dry Valleys ◽  
Dna Homology ◽  
Dna Base Composition ◽  
Dna Base ◽  
Dna Homologies ◽  
Antarctic Yeasts

The 16 biotypes of the Cryptococcus vishniacii complex of anamorphic yeasts (Basidioblastomycetes), unique to the Dry Valleys of Antarctica, include seven species separated by DNA–DNA homologies of less than 52%. Since species belonging to the complex can be as distantly related as C. bhutanensis (a Himalayan yeast, guanine + cytosine (G + C) 54.18 mol%) is to these species, a common ancestor probably originated and speciated outside of the Dry Valleys. The species C. vishniacii (G + C 54.52–55.48 mol%) comprises seven varieties with greater than 59% DNA–DNA homology and must therefore have been established in the Dry Valleys long enough to have evolved these divergent genomes. In the C. vishniacii complex, G + C values differing by more than 1 mol% are accompanied by DNA–DNA homologies of less than 23%.

Deoxyribonucleic acid relationships among marine vibrios pathogenic to fish

1977 ◽  
Vol 23 (8) ◽  
pp. 954-958 ◽  
Author(s):  
Michael H. Schiewe ◽  
Jorge H. Crosa ◽  
Erling J. Ordal
Keyword(s):  
Pacific Northwest ◽  
Vibrio Anguillarum ◽  
Significant Degree ◽  
Dna Homology ◽  
Homology Groups ◽  
Dna Base ◽  
The Pacific ◽  
Related Group ◽  
Marine Vibrios ◽  
Sequence Relationships

Polynucleotide sequence relationships among 19 strains of marine vibrios, 15 of which were pathogenic to fish, were assessed by analysis of DNA–DNA homo- and hetero-duplexes with the endonuclease S1. DNA base compositions (mole% guanine–cytosine (GC) of selected vibrio strains were determined by thermal denaturation. Pathogenic strains from the Pacific Northwest had identical mole % GC but could be divided into two discrete, yet related, DNA-homology groups. One highly related group was typical of Vibrio anguillarum and showed greater than 70% within-group polynucleotide sequence homology. Second group (designated V1669) showed greater than 83% within-group homology but only about 60% relatedness to V. anguillarum. Neither group showed a significant degree of relatedness to V. parahaemolyticus (biotypes parahaemolyticus or alginolyticus) or to representative strains of any of the other previously described homology groups which we tested.

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