The genus Pseudomonas described in 1894 is one of the most diverse and ubiquitous bacterial genera which encompass species isolated worldwide. In the last years more than 70 new species have been ...described, which were isolated from different environments, including soil, water, sediments, air, animals, plants, fungi, algae, compost, human and animal related sources. Some of these species have been isolated in extreme environments, such as Antarctica or Atacama desert, and from contaminated water or soil. Also, some species recently described are plant or animal pathogens. In this review, we revised the current status of the taxonomy of genus Pseudomonas and the methodologies currently used for the description of novel species which includes, in addition to the classic ones, new methodologies such as MALDI-TOF MS, MLSA and genome analyses. The novel Pseudomonas species described in the last years are listed, together with the available genome sequences of the type strains of Pseudomonas species present in different databases.
•The Pseudomonas taxonomy continues actively progressing, with more than 70 novel species described in the last years.•The analysis of complete genomes is very useful in Pseudomonas taxonomy and in the knowledge of the biology of their species.•The diverse habitats and biological abilities of recently described Pseudomonas species show their huge metabolic versatility.
History and current taxonomic status of genus Agrobacterium Flores-Félix, José David; Menéndez, Esther; Peix, Alvaro ...
Systematic and applied microbiology,
January 2020, 2020-Jan, 2020-01-00, 20200101, Letnik:
43, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The genus Agrobacterium was created a century ago by Conn who included it in the family Rhizobiaceae together with the genus Rhizobium. Initially, the genus Agrobacterium contained the non-pathogenic ...species Agrobacterium radiobacter and the plant pathogenic species Agrobacterium tumefaciens and Agrobacterium rhizogenes. At the end of the past century two new pathogenic species, Agrobacterium rubi and Agrobacterium vitis, were added to the genus. Already in the present century these species plus Agrobacterium larrymoorei were reclassified into genus Rhizobium. This reclassification was controversial and for a time both genus names were used when new species were described. Few years ago, after a taxonomic revision based on genomic data, the old species A. rhizogenes was maintained in the genus Rhizobium, the old species A. vitis was transferred to the genus Allorhizobium and several Rhizobium species were transferred to the genus Agrobacterium, which currently contains 14 species including the old species A. radiobacter, A. tumefaciens, A. rubi and A. larrymoorei. Most of these species are able to produce tumours in different plants, nevertheless the genus Agrobacterium also encompasses non-pathogenic species, one species able to nodulate legumes and one human pathogenic species. Taking into account that the species affiliations to five Agrobacterium genomospecies have not been determined yet, an increase in the number of species within this genus is expected in the near future.
The genus
Pseudomonas was described in 1894 and is one of the most diverse and ubiquitous bacterial genera whose species have been isolated worldwide in all kinds of environments, from the Antarctica ...to the Tropics, present in sediments, clinical samples, plant, fungi and diseased animal specimens, water, soil, plant rhizosphere, sea, deserts, etc. The taxonomy of the genus has been controversial for years since a lot of bacterial taxa initially included in genus
Pseudomonas have been reclassified in other genera or species from a different class of
Proteobacteria over the years, as techniques for characterization and classification of microorganisms improved, aiming to set a phylogenetic classification of the species. In this review, the historical evolution of the taxonomy of
Pseudomonas is described, and the currently valid criteria and future challenges for taxonomy of the genus and techniques used to achieve the necessary characterization for classifying the species are discussed. Finally, all the validly published
Pseudomonas species at present are listed with an overview of their diversity and ecology.
Two rod-shaped Gram negative strains, SSUT16T and SSUT22, were isolated from root nodules of Spartocytisus supranubius in soils of the Teide National Park (Tenerife, Spain). The 16S rRNA gene ...sequences of these two novel strains classified them within genus Bosea with similarity values ranging from 97.65 % to 99.54 % with respect to the other species of this genus. The MLSA analysis from a concatenation of the two housekeeping- genes, recA and gyrB, showed that Bosea thiooxidans LMG 26210T and B. robiniae LMG 26381T are the two closest relative species with which they share similarity sequences values of 94.42 % and 94.27 %, respectively. The genome sequence analysis of strain SSUT16T showed average nucleotide identity percentages (ANIb) and digital DNA-DNA hybridization (dDDH) below 84 % and 33 %, respectively, with the type strains of all sequenced species of genus Bosea. These values are much lower than the currently accepted cut-off values for these two parameters to delineate bacterial species, confirming that the novel strains constitute a novel Bosea species. In addition, they are also distinguished from the other closest species in their fatty acid composition and in other phenotypic characteristics. Genome sequence analysis showed the absence of the common nodulation and nitrogen fixation genes in the novel strains. Therefore, based on the results of phylogenetic, genomic, chemotaxonomic and phenotypic characterization, we propose a new species named Bosea spartocytisi sp. nov., with type strain SSUT16T (=LMG 32510T = CECT 30526T = HAMBI 3759T).
Vigna unguiculata was introduced into Europe from its distribution centre in Africa, and it is currently being cultivated in Mediterranean regions with adequate edapho-climatic conditions where the ...slow growing rhizobia nodulating this legume have not yet been studied. Previous studies based on rrs gene and ITS region analyses have shown that Bradyrhizobium yuanmingense and B. elkanii nodulated V. unguiculata in Africa, but these two species were not found in this study. Using the same phylogenetic markers it was shown that V. unguiculata, a legume from the tribe Phaseolae, was nodulated in Spain by two species of group I, B. cytisi and B. canariense, which are common endosymbionts of Genisteae in both Europe and Africa. These species have not been found to date in V. unguiculata nodules in its African distribution centres. All strains from Bradyrhizobium group I isolated in Spain belonged to the symbiovar genistearum, which is found at present only in Genisteae legumes in both Africa and Europe. V. unguiculata was also nodulated in Spain by a strain from Bradyrhizobium group II that belonged to a novel symbiovar (vignae). Some African V. unguiculata-nodulating strains also belonged to this proposed new symbiovar.
The species Rhizobium lupini was isolated from Lupinus nodules and included in the Approved Lists of Bacterial Names in 1980. Nevertheless, on the basis of the analysis of the type strain of this ...species available in DSMZ, DSM 30140 ᵀ, whose 16S rRNA gene was identical to that of the type strain of Bradyrhizobium japonicum , R. lupini was considered a later synonym of this species. In this study we confirmed that the strain DSM 30140 ᵀ belongs to the species B. japonicum , but also that it cannot be the original strain of R. lupini because this species effectively nodulated Lupinus whereas strain DSM 30140 ᵀ was able to nodulate soybean but not Lupinus . Since the original type strain of R. lupini was deposited into the USDA collection by L. W. Erdman under the accession number USDA 3051 ᵀ we analysed the taxonomic status of this strain showing that although it belongs to the genus Bradyrhizobium instead of genus Rhizobium , it is phylogenetically distant from B. japonicum and closely related to Bradyrhizobium canariense . The type strains R. lupini USDA 3051 ᵀ and B. canariense BTA-1 ᵀ share 16S rRNA, recA and glnII gene sequences with similarities of 99.8 %, 96.5 % and 97.1 %, respectively. They presented a DNA–DNA hybridization value of 36 % and also differed in phenotypic characteristics and slightly in the proportions of some fatty acids. Therefore we propose the reclassification of the species Rhizobium lupini as Bradyrhizobium lupini comb. nov. The type strain is USDA 3051 ᵀ (= CECT 8630 ᵀ = LMG 28514 ᵀ).
We isolated a bacterial strain designated PCAVU11(T) in the course of a study of phosphate-solubilizing bacteria occurring in rhizospheric soil of Vigna unguiculata (L.) Walp. in Guárico state, ...Venezuela. The 16S rRNA gene sequence had 99.2 % sequence similarity with respect to the most closely related species, Pseudomonas taiwanensis, and 99.1 % with respect to Pseudomonas entomophila, Pseudomonas plecoglossicida and Pseudomonas monteilii, on the basis of which PCAVU11(T) was classified as representing a member of the genus Pseudomonas. Analysis of the housekeeping genes rpoB, rpoD and gyrB confirmed the phylogenetic affiliation and showed sequence similarities lower than 95 % in all cases with respect to the above-mentioned closest relatives. Strain PCAVU11(T) showed two polar flagella. The respiratory quinone was Q9. The major fatty acids were 16 : 0 (25.7 %), 18 : 1ω7c (20.4 %), 17 : 0 cyclo (11.5 %) and 16 : 1ω7c/15 : 0 iso 2-OH in summed feature 3 (10.8 %). The strain was oxidase-, catalase- and urease-positive, the arginine dihydrolase system was present but nitrate reduction, β-galactosidase production and aesculin hydrolysis were negative. Strain PCAVU11(T) grew at 44 °C and at pH 10. The DNA G+C content was 61.5 mol%. DNA-DNA hybridization results showed values lower than 56 % relatedness with respect to the type strains of the four most closely related species. Therefore, the results of genotypic, phenotypic and chemotaxonomic analyses support the classification of strain PCAVU11(T) as representing a novel species of the genus Pseudomonas, which we propose to name Pseudomonas guariconensis sp. nov. The type strain is PCAVU11(T) ( = LMG 27394(T) = CECT 8262(T)).
The species Lactococcus lactis currently includes three subspecies; L. lactis subsp. lactis and L. lactis subsp. cremoris, isolated from milk sources, and L. lactis subsp. hordniae, isolated from the ...leafhopper Hordnia circellata. In this study, three strains, designated L105(T), I3 and L101, were isolated from the intestinal mucus of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). These strains were closely related to members of the species Lactococcus lactis. Strain L105(T) showed 99.4 % 16S rRNA gene sequence similarity to that of the type strains L. lactis subsp. lactis NCDO 604(T) and L. lactis subsp. hordniae NCDO 2181(T) and showed 99.9 % similarity to the type strain Lactococcus lactis subsp. cremoris NCDO 607(T). Analysis of two housekeeping genes, rpoB and recA, confirmed the close relationship between the novel strains and L. lactis subsp. cremoris with similarities of 99.3 and 99.7 %, respectively. The three strains could, however, be differentiated from their closest relatives on the basis of several phenotypic characteristics, as was the case for L. lactis subsp. lactis and L. lactis subsp. hordniae, which were also closely related on the basis of 16S rRNA, rpoB and recA gene sequence similarities. The strains isolated in this study represent a new subspecies, for which the name Lactococcus lactis subsp. tructae subsp. nov. is proposed. The type strain is L105(T) ( = LMG 24662(T) = DSM 21502(T)).
A bacterial strain designated RLAHU4BT was isolated from root nodules of Lupinus albus in León (Spain). The 16S rRNA gene sequence of this strain showed similarities lower than 97 % with respect to ...species of the genus Cohnella. The strain was a Gram-variable, sporulating rod, motile by means of peritrichous flagella, and facultatively anaerobic. It was positive for oxidase, catalase and β-galactosidase production but negative for urease, amylase and gelatinase. Strain RLAHU4BT grew in the presence of 5 % NaCl. MK-7 was the predominant menaquinone and meso-diaminopimelic acid was present in the peptidoglycan. anteiso-C15 : 0, iso-C16 : 0, iso-C15 : 0 and C16 : 0 were the major fatty acids. Major polar lipids of strain RLAHU4BT were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown phospholipids, two unknown aminophospholipids and one unknown lipid. The DNA G+C content was 57.8 mol%. Strain RLAHU4BT presented phenotypic differences from all recognized species of the genus Cohnella. The phylogenetic, chemotaxonomic and phenotypic data indicated that strain RLAHU4BT belongs to a novel species of the genus Cohnella, for which the name Cohnella lupini sp. nov. is proposed, with strain RLAHU4BT ( = LMG 27416T = CECT 8236T) as the type strain.
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