scholarly journals Multilocus sequence analysis of the family Halomonadaceae

2012 ◽  
Vol 62 (Pt_3) ◽  
pp. 520-538 ◽  
Author(s):  
Rafael R. de la Haba ◽  
M. Carmen Márquez ◽  
R. Thane Papke ◽  
Antonio Ventosa

Multilocus sequence analysis (MLSA) protocols have been developed for species circumscription for many taxa. However, at present, no studies based on MLSA have been performed within any moderately halophilic bacterial group. To test the usefulness of MLSA with these kinds of micro-organisms, the family Halomonadaceae, which includes mainly halophilic bacteria, was chosen as a model. This family comprises ten genera with validly published names and 85 species of environmental, biotechnological and clinical interest. In some cases, the phylogenetic relationships between members of this family, based on 16S rRNA gene sequence comparisons, are not clear and a deep phylogenetic analysis using several housekeeping genes seemed appropriate. Here, MLSA was applied using the 16S rRNA, 23S rRNA, atpA, gyrB, rpoD and secA genes for species of the family Halomonadaceae. Phylogenetic trees based on the individual and concatenated gene sequences revealed that the family Halomonadaceae formed a monophyletic group of micro-organisms within the order Oceanospirillales. With the exception of the genera Halomonas and Modicisalibacter, all other genera within this family were phylogenetically coherent. Five of the six studied genes (16S rRNA, 23S rRNA, gyrB, rpoD and secA) showed a consistent evolutionary history. However, the results obtained with the atpA gene were different; thus, this gene may not be considered useful as an individual gene phylogenetic marker within this family. The phylogenetic methods produced variable results, with those generated from the maximum-likelihood and neighbour-joining algorithms being more similar than those obtained by maximum-parsimony methods. Horizontal gene transfer (HGT) plays an important evolutionary role in the family Halomonadaceae; however, the impact of recombination events in the phylogenetic analysis was minimized by concatenating the six loci, which agreed with the current taxonomic scheme for this family. Finally, the findings of this study also indicated that the 16S rRNA, gyrB and rpoD genes were the most suitable genes for future taxonomic studies using MLSA within the family Halomonadaceae.

Author(s):  
Xiaoying Rong ◽  
Ying Huang

Streptomyces griseus and related species form the biggest but least well-defined clade in the whole Streptomyces 16S rRNA gene tree. Multilocus sequence analysis (MLSA) has shown promising potential for refining Streptomyces systematics. In this investigation, strains of 18 additional S. griseus clade species were analysed and data from a previous pilot study were integrated in a larger MLSA phylogeny. The results demonstrated that MLSA of five housekeeping genes (atpD, gyrB, recA, rpoB and trpB) is better than the previous six-gene scheme, as it provides equally good resolution and stability and is more cost-effective; MLSA using three or four of the genes also shows good resolution and robustness for differentiating most of the strains and is therefore of value for everyday use. MLSA is more suitable for discriminating strains that show >99 % 16S rRNA gene sequence similarity. DNA–DNA hybridization (DDH) between strains with representative MLSA distances revealed a strong correlation between the data of MLSA and DDH. The 70 % DDH value for current species definition corresponds to a five-gene MLSA distance of 0.007, which could be considered as the species cut-off for the S. griseus clade. It is concluded that the MLSA procedure can be a practical, reliable and robust alternative to DDH for the identification and classification of streptomycetes at the species and intraspecies levels. Based on the data from MLSA and DDH, as well as cultural and morphological characteristics, 18 species and three subspecies of the S. griseus clade are considered to be later heterotypic synonyms of 11 genomic species: Streptomyces griseinus and Streptomyces mediolani as synonyms of Streptomyces albovinaceus; Streptomyces praecox as a synonym of Streptomyces anulatus; Streptomyces olivoviridis as a synonym of Streptomyces atroolivaceus; Streptomyces griseobrunneus as a synonym of Streptomyces bacillaris; Streptomyces cavourensis subsp. washingtonensis as a synonym of Streptomyces cyaneofuscatus; Streptomyces acrimycini, Streptomyces baarnensis, Streptomyces caviscabies and Streptomyces flavofuscus as synonyms of Streptomyces fimicarius; Streptomyces flavogriseus as a synonym of Streptomyces flavovirens; Streptomyces erumpens, ‘Streptomyces ornatus’ and Streptomyces setonii as synonyms of Streptomyces griseus; Streptomyces graminofaciens as a synonym of Streptomyces halstedii; Streptomyces alboviridis, Streptomyces griseus subsp. alpha, Streptomyces griseus subsp. cretosus and Streptomyces luridiscabiei as synonyms of Streptomyces microflavus; and Streptomyces californicus and Streptomyces floridae as synonyms of Streptomyces puniceus.


2010 ◽  
Vol 60 (4) ◽  
pp. 963-971 ◽  
Author(s):  
Rafael R. de la Haba ◽  
Cristina Sánchez-Porro ◽  
M. Carmen Márquez ◽  
Antonio Ventosa

We have carried out a polyphasic taxonomic characterization of the type strains of the species with the recently validated name Salinicola socius, together with two species that were phylogenetically closely related, Halomonas salaria and Chromohalobacter salarius. 16S rRNA gene sequence analyses showed that they constituted a coherent cluster, with sequence similarities between 98.7 and 97.7 %. We have determined the almost complete 23S rRNA gene sequences of these three type strains, and the percentage of similarity between them was 99.2–97.6 %. Phylogenetic trees based on the 16S rRNA and 23S rRNA gene sequences, obtained by using three different algorithms, were consistent and showed that these three species constituted a cluster separated from the other species of the genera of the family Halomonadaceae, supporting their placement in a single genus. All three species have ubiquinone 9 as the major respiratory quinone, and showed similar fatty acid and polar lipid profiles. The level of DNA–DNA hybridization between Salinicola socius DSM 19940T, Halomonas salaria DSM 18044T and Chromohalobacter salarius CECT 5903T was 41–21 %, indicating that they are different species of the genus Salinicola. A comparative phenotypic study of these strains following the proposed minimal standards for describing new taxa of the family Halomonadaceae has been carried out. The phenotypic data are consistent with the placement of these three species in a single genus and support their differentiation at the species level. On the basis of these data we have emended the description of the species Salinicola socius and we propose to transfer the species Halomonas salaria and Chromohalobacter salarius to the genus Salinicola, as Salinicola salarius comb. nov. (type strain M27T =KCTC 12664T =DSM 18044T) and Salinicola halophilus nom. nov. (type strain CG4.1T =CECT 5903T =LMG 23626T), respectively.


2010 ◽  
Vol 60 (4) ◽  
pp. 737-748 ◽  
Author(s):  
Rafael R. de la Haba ◽  
David R. Arahal ◽  
M. Carmen Márquez ◽  
Antonio Ventosa

A phylogenetic study of the family Halomonadaceae was carried out based on complete 16S rRNA and 23S rRNA gene sequences. Several 16S rRNA genes of type strains were resequenced, and 28 new sequences of the 23S rRNA gene were obtained. Currently, the family includes nine genera (Carnimonas, Chromohalobacter, Cobetia, Halomonas, Halotalea, Kushneria, Modicisalibacter, Salinicola and Zymobacter). These genera are phylogenetically coherent except Halomonas, which is polyphyletic. This genus comprises two clearly distinguished clusters: group 1 includes Halomonas elongata (the type species) and the species Halomonas eurihalina, H. caseinilytica, H. halmophila, H. sabkhae, H. almeriensis, H. halophila, H. salina, H. organivorans, H. koreensis, H. maura and H. nitroreducens. Group 2 comprises the species Halomonas aquamarina, H. meridiana, H. axialensis, H. magadiensis, H. hydrothermalis, H. alkaliphila, H. venusta, H. boliviensis, H. neptunia, H. variabilis, H. sulfidaeris, H. subterranea, H. janggokensis, H. gomseomensis, H. arcis and H. subglaciescola. Halomonas salaria forms a cluster with Chromohalobacter salarius and the recently described genus Salinicola, and their taxonomic affiliation requires further study. More than 20 Halomonas species are phylogenetically not within the core constituted by the Halomonas sensu stricto cluster (group 1) or group 2 and, since their positions on the different phylogenetic trees are not stable, they cannot be recognized as additional groups either. In general, there is excellent agreement between the phylogenies based on the two rRNA gene sequences, but the 23S rRNA gene showed higher resolution in the differentiation of species of the family Halomonadaceae.


2007 ◽  
Vol 57 (7) ◽  
pp. 1535-1538 ◽  
Author(s):  
Ivone Vaz-Moreira ◽  
M. Fernanda Nobre ◽  
Olga C. Nunes ◽  
Célia M. Manaia

A bacterial strain, DC-186T, isolated from home-made compost, was characterized for its phenotypic and phylogenetic properties. The isolate was a Gram-negative rod that was able to grow at 15–36 °C and pH 5.5–8.0. Strain DC-186T was positive in tests for catalase, oxidase and β-galactosidase activities and aesculin hydrolysis. The predominant fatty acids were the summed feature C16 : 1/iso-C15 : 0 2-OH (42 %) and iso-C15 : 0 (26 %), the major respiratory quinone was menaquinone-7 and the genomic DNA G+C content was 42 mol%. 16S rRNA gene sequence analysis and phenetic characterization indicated that this organism belongs to the phylum Bacteroidetes and revealed its affiliation to the family Sphingobacteriaceae. Of recognized taxa, strain DC-186T was most closely related to Sphingobacterium daejeonense (90 % sequence similarity) based on 16S rRNA gene sequence analysis. The low 16S rRNA gene sequence similarity with other recognized taxa and the identification of distinctive phenetic features for this isolate support the definition of a new genus within the family Sphingobacteriaceae. The name Pseudosphingobacterium domesticum gen. nov., sp. nov. is proposed, with strain DC-186T (=CCUG 54353T=LMG 23837T) as the type strain.


2007 ◽  
Vol 57 (3) ◽  
pp. 489-503 ◽  
Author(s):  
Miet Martens ◽  
Manuel Delaere ◽  
Renata Coopman ◽  
Paul De Vos ◽  
Monique Gillis ◽  
...  

Multilocus sequence analysis (MLSA) was performed on representatives of Ensifer (including species previously assigned to the genus Sinorhizobium) and related taxa. Neighbour-joining (NJ), maximum-parsimony (MP) and maximum-likelihood (ML) phylogenies of dnaK, gltA, glnA, recA, thrC and 16S rRNA genes were compared. The data confirm that the potential for discrimination of Ensifer species is greater using MLSA of housekeeping genes than 16S rRNA genes. In incongruence-length difference tests, the 16S rRNA gene was found to be significantly incongruent with the other genes, indicating that this gene should not be used as a single indicator of relatedness in this group. Significant congruence was detected for dnaK, glnA and thrC. Analyses of concatenated sequences of dnaK, glnA and thrC genes yielded very similar NJ, MP and ML trees, with high bootstrap support. In addition, analysis of a concatenation of all six genes essentially produced the same result, levelling out potentially conflicting phylogenetic signals. This new evidence supports the proposal to unite Ensifer and Sinorhizobium in a single genus. Support for an alternative solution preserving the two genera is less strong. In view of the opinions expressed by the Judicial Commission, the name of the genus should be Ensifer, as proposed by Young [Young, J. M. (2003). Int J Syst Evol Microbiol 53, 2107–2110]. Data obtained previously and these new data indicate that Ensifer adhaerens and ‘Sinorhizobium morelense’ are not heterotypic synonyms, but represent separate species. However, transfer to the genus Ensifer is not possible at present because the species name is the subject of a pending Request for an Opinion, which would affect whether a novel species in the genus Ensifer or a new combination based on a basonym would be created.


2007 ◽  
Vol 57 (4) ◽  
pp. 666-674 ◽  
Author(s):  
P. J. Blackall ◽  
Anders Miki Bojesen ◽  
Henrik Christensen ◽  
Magne Bisgaard

[Pasteurella] trehalosi is an important pathogen of sheep, being primarily associated with serious systemic infections in lambs but also having an association with pneumonia. The aim of the present investigation was to characterize a broad collection of strains tentatively identified as [P.] trehalosi in order to reclassify and rename this taxon to support improvements in our understanding of the pathogenesis and epidemiology of this important organism. The type strain for [P.] trehalosi, strain NCTC 10370T, was included along with 42 field isolates from sheep (21), cattle (14), goats (1), roe deer (3) and unknown sources (3). An extended phenotypic characterization was performed on all 43 strains. Amplified fragment length polymorphism (AFLP) was also performed on the isolates. Two of the field isolates were subjected to 16S rRNA gene sequencing. These sequences, along with five existing sequences for [P.] trehalosi strains and 12 sequences for other taxa in the family Pasteurellaceae, were subjected to a phylogenetic analysis. All the isolates and the reference strains were identified as [P.] trehalosi. A total of 17 out of 22 ovine isolates produced acid from all glycosides, while only four out of 14 bovine isolates produced acid from all glycosides. All 22 ovine isolates were haemolytic and CAMP-positive, while no other isolate was haemolytic and only two bovine isolates were CAMP-positive. Nineteen AFLP types were found within the [P.] trehalosi isolates. All [P.] trehalosi isolates shared at least 70 % similarity in AFLP patterns. The largest AFLP type included the type strain and 7 ovine field isolates. Phylogenetic analysis indicated that the seven strains studied (two field isolates and the five serovar reference strains) are closely related, with 98.6 % or higher 16S rRNA gene sequence similarity. As both genotypic and phenotypic testing support the separate and distinct nature of these organisms, we propose the transfer of [P.] trehalosi to a new genus, Bibersteinia, as Bibersteinia trehalosi comb. nov. The type strain is NCTC 10370T (=ATCC 29703T). Bibersteinia trehalosi can be distinguished from the existing genera of the family by the observation of only nine characteristics; catalase, porphyrin, urease, indole, phosphatase, acid from dulcitol, (+)-d-galactose, (+)-d-mannose and (+)-d-trehalose.


2007 ◽  
Vol 57 (7) ◽  
pp. 1673-1674 ◽  
Author(s):  
Masami Morotomi ◽  
Fumiko Nagai ◽  
Hiroshi Sakon

Megamonas hypermegale is the sole species of the genus Megamonas included in the List of Prokaryotic Names with Standing in Nomenclature and in the databases of DDBJ, EBI/EMBL and NCBI/GenBank it is placed in the lineage of Bacteroidetes; Bacteroidetes (class); ‘Bacteroidales’; Bacteroidaceae; Megamonas. Phylogenetic analysis based on comparative 16S rRNA gene sequencing showed that this species clustered with species of the family ‘Acidaminococcaceae’ but not with those of the Bacteroidaceae. The genus Megamonas should be placed in the lineage of Firmicutes; Clostridia; Clostridiales; ‘Acidaminococcaceae’; Megamonas.


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