species definition
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Author(s):  
Paolo Bellassi ◽  
Alessandra Fontana ◽  
Maria Luisa Callegari ◽  
Fabrizio Cappa ◽  
Lorenzo Morelli

A novel Gram-stain-positive, strictly aerobic, short rod-shaped bacterium, designated 2CT, was isolated from freshly packaged microfiltered milk. This strain was able to grow within the NaCl concentration range of 0–5 % (w/v), temperature range of 8–37 °C (optimally at 30 °C) and at pH 6.0–10.0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 2CT was closely related to species of the genus Microbacterium , with the highest sequence similarity (99.2 %) to Microbacterium lacticum DSM 20427T as well as Microbacterium flavum DSM 18909T (=YM18-098T). The phylogenetic tree based on 16S rRNA genes showed that strain 2CT clustered with M. flavum DSM 18909T. However, the phylogenetic tree based on concatenated 16S rRNA and four housekeeping genes showed that strain 2CT clustered with M. lacticum DSM 20427T. Furthermore, the phylogenomic tree showed that strain 2CT clustered with M. lacticum DSM 20427T and M. flavum DSM 18909T. The major respiratory quinones were MK-10, MK-11 and MK-12. The predominant cellular fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The polar lipid composition of strain 2CT consisted of diphosphatidylglycerol, phosphatidylglycerol, three unidentified glycolipids and two unidentified lipids. The cell-wall peptidoglycan type was a variant of B1α {Gly} [l-Lys] d-Glu-l-Lys, with the amino acids lysine, glycine, alanine and glutamic acid. The whole-cell sugars consisted of galactose, glucose, ribose and minor amounts of rhamnose. In addition, strain 2CT showed a glycolyl-type cell wall. The genomic DNA G+C content was 69.8mol%, while the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values with the closely related Microbacterium species were below the recognized thresholds of 95–96 % ANI and 70 % DDH for species definition. Based on the phenotypic and genotypic data, strain 2CT (=LMG 32277T=CECT 30329T) is considered to represent a new species, for which the name Microbacterium paulum sp. nov. is proposed.


2021 ◽  
Author(s):  
Donovan H Parks ◽  
Maria Chuvochina ◽  
Peter R Reeves ◽  
Scott A Beatson ◽  
Philip Hugenholtz

Members of the genus Shigella have high genomic similarity to Escherichia coli and are often considered to be atypical members of this species. In an attempt to retain Shigella species as recognizable entities, they were reclassified as Escherichia species in the Genome Taxonomy Database (GTDB) using an operational average nucleotide identity (ANI)-based approach nucleated around type strains. This resulted in nearly 80% of E. coli genomes being reclassified to new species including the common laboratory strain E. coli K-12 (to 'E. flexneri') because it is more closely related to the type strain of Shigella flexneri than it is to the type strain of E. coli. Here we resolve this conundrum by treating Shigella species as later heterotypic synonyms of E. coli, present evidence supporting this reclassification, and show that assigning E. coli/Shigella strains to a single species is congruent with the GTDB-adopted genomic species definition.


Author(s):  
Tao Pei ◽  
Juan Du ◽  
Yang Liu ◽  
Ming-Rong Deng ◽  
Honghui Zhu

A novel Gram-stain-negative and rod-shaped bacterial strain, designated as 4Y14T, was isolated from aquaculture water and characterized by using a polyphasic taxonomic approach. Strain 4Y14T was found to grow at 10–40 °C (optimum, 28 °C), at pH 7.0–9.0 (optimum, 7.0–8.0) and with 0–2 % NaCl (optimum, 1 %, w/v). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 4Y14T belonged to the genus Chitinilyticum with high levels of similarity to Chitinilyticum litopenaei c1T (97.8 %) and Chitinilyticum aquatile c14T (97.2 %). Phylogenomic analysis indicated that strain 4Y14T formed an independent branch distinct from the two type strains above. Digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain 4Y14T and the two type strains were, respectively, 25.3 and 25.0 %, and 81.2 and 80.3 %, which were well below the thresholds of 70 % DDH and 95–96 % ANI for species definition, implying that strain 4Y14T should represent a novel genospecies. The predominant cellular fatty acids of strain 4Y14T were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and iso-C16 : 0; the major polar lipids were diphosphatidylglycerol, phosphatidylcholine and phosphatidylethanolamine; and the sole respiratory quinone was Q-8. The genomic DNA G+C content was 60.1 mol%. Based on the phenotypic and genotypic analyses, strain 4Y14T is concluded to represent a novel species of the genus Chitinilyticum , for which the name Chitinilyticum piscinae sp. nov. is proposed. The type strain of the species is 4Y14T (=GDMCC 1.1934T=KACC 22080T).


Author(s):  
Juan Du ◽  
Yang Liu ◽  
Tao Pei ◽  
Ming-Rong Deng ◽  
Honghui Zhu

A novel Gram-stain-negative, aerobic and rod-shaped bacterial strain designated as 6D45AT was isolated from mangrove soil and characterized using a polyphasic taxonomic approach. Strain 6D45AT was found to grow at 10–37 °C (optimum, 28 °C), at pH 6.0–9.0 (optimum, 7.0) and in 0–5 % (w/v) NaCl (optimum, 2%). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 6D45AT fell into the genus Salipiger and shared 99.1 % identity with the closest type strain Salipiger pacificus CGMCC 1.3455T and less than 97.2 % identity with other type strains of this genus. The 34.8 % digital DNA–DNA hybridization (dDDH) and 88.3 % average nucleotide identity (ANI) values between strain 6D45AT and the closest relative above were well below recognized thresholds of 70 % DDH and 95–96 % ANI for species definition, implying that strain 6D45AT should represent a novel genospecies. The phylogenomic analysis indicated that strain 6D45AT formed an independent branch distinct from reference strains. The predominant cellular fatty acid of strain 6D45AT was summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c, 66.9 %); the polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, two unidentified aminolipids, two unidentified glycolipids and an unknown lipid; the respiratory quinone was Q-10. The genomic DNA G+C content was 66.5 mol %. Based on the phenotypic and genotypic characteristics, strain 6D45AT is concluded to represent a novel species of the genus Salipiger , for which the name Salipiger mangrovisoli sp. nov., is proposed. The type strain of the species is 6D45AT (=GDMCC 1.1960T=KCTC 82334T). We also propose the reclassification of Paraphaeobacter pallidus as Salipiger pallidus comb. nov. and ‘ Pelagibaca abyssi ’ as a species of the genus Salipiger .


2021 ◽  
Author(s):  
Tao Pei ◽  
Yang Liu ◽  
Juan Du ◽  
Kun peng Huang ◽  
Ming rong Deng ◽  
...  

Abstract A novel Gram-staining-negative and short-rod-shaped bacterial strain designated as 1NDH52T was isolated from tidal flat sediments and characterized by using a polyphasic taxonomic approach. The predominant cellular fatty acids of strain 1NDH52T were summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and C14:0 2-OH; the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid; the major respiratory quinones were Q-10 and Q-9. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 1NDH52T belonged to the genus Croceicoccus with high similarities to the close type strains Croceicoccus pelagius Ery9T, Croceicoccus sediminis S2-4-2T and Croceicoccus bisphenolivorans H4T. Phylogenomic analysis indicated that strain 1NDH52T formed an independent branch distinct from the known type strains of this genus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain 1NDH52T and the three type strains above were well below thresholds of 70% DDH and 95-96% ANI for species definition, implying that strain 1NDH52T should represent a novel genospecies. The genomic DNA G + C content was 62.6%. The carotenoids production of the novel strain was determined by the detection of the pigment absorption spectrum and the identification of the complete biosynthetic gene cluster in its genome. Based on the phenotypic and genotypic characteristics, strain 1NDH52T is concluded to represent a novel species of the genus Croceicoccus, for which the name Croceicoccus gelatinilyticus sp. nov., is proposed. The type strain of the species is 1NDH52T (= GDMCC 1.2381T = KCTC 82668T). The description of the genus Croceicoccus has also been emended.


2021 ◽  
Vol 9 ◽  
Author(s):  
Gabriella Marincola ◽  
Olivia Liong ◽  
Christoph Schoen ◽  
Alaa Abouelfetouh ◽  
Aisha Hamdy ◽  
...  

Coagulase-negative staphylococci (CoNS) are common opportunistic pathogens, but also ubiquitous human and animal commensals. Infection-associated CoNS from healthcare environments are typically characterized by pronounced antimicrobial resistance (AMR) including both methicillin- and multidrug-resistant isolates. Less is known about AMR patterns of CoNS colonizing the general population. Here we report on AMR in commensal CoNS recovered from 117 non-hospitalized volunteers in a region of Germany with a high livestock density. Among the 69 individuals colonized with CoNS, 29 had reported contacts to either companion or farm animals. CoNS were selectively cultivated from nasal swabs, followed by species definition by 16S rDNA sequencing and routine antibiotic susceptibility testing. Isolates displaying phenotypic AMR were further tested by PCR for presence of selected AMR genes. A total of 127 CoNS were isolated and Staphylococcus epidermidis (75%) was the most common CoNS species identified. Nine isolates (7%) were methicillin-resistant (MR) and carried the mecA gene, with seven individuals (10%) being colonized with at least one MR-CoNS isolate. While resistance against gentamicin, phenicols and spectinomycin was rare, high resistance rates were found against tetracycline (39%), erythromycin (33%) and fusidic acid (24%). In the majority of isolates, phenotypic resistance could be associated with corresponding AMR gene detection. Multidrug-resistance (MDR) was observed in 23% (29/127) of the isolates, with 33% (23/69) of the individuals being colonized with MDR-CoNS. The combined data suggest that MR- and MDR-CoNS are present in the community, with previous animal contact not significantly influencing the risk of becoming colonized with such isolates.


2021 ◽  
Author(s):  
Xiong Chen ◽  
Linyuan Fan ◽  
Jian Huang ◽  
Guohua Zhou ◽  
Yuan Huang

Abstract Backgroud: Aucuba (Garryaceae), which includes approximately 10 evergreen woody species, is a genus endemic to East Asia. Their striking morphological features give Aucuba species remarkable ornamental value. Owing to high levels of morphological divergence and plasticity, species definition of Aucuba remains perplexing and problematic. Here, we sequenced and characterized the complete plastid genomes (plastomes) of three Aucuba species: Aucuba chlorascens, Aucuba eriobotryifolia, and Aucuba japonica. Results: Comparative analyses revealed that Aucuba plastomes are highly conserved in size, structure, gene content, and organization, and exhibit high levels of sequence similarity. We recommend 11 plastid DNA regions as potential DNA barcodes for species identification and genotyping of Aucuba germplasm. Phylogenetic reconstruction based on 71 plastid protein-coding genes from taxa encompassing a wide phylogenetic diversity in the lamiids strongly supported the sister relationship between Garryaceae and Eucommiaceae. Conclusion: Plastome tree revealed the monophyly of Garryales, offering plastid phylogenomic evidence for the acceptance of Garryales as outlined by the updated Angiosperm Phylogeny Group. Under a comparative framework within Garryales, we detected massive plastome arrangements between Aucuba and Eucommia. In summary, our study provides useful genomic resources for further study of the taxonomy, evolution, conservation, and exploitation of Aucuba species.


Author(s):  
Yang Liu ◽  
Tao Pei ◽  
Juan Du ◽  
Meijie Chao ◽  
Ming-Rong Deng ◽  
...  

A novel Gram-stain-negative, facultatively anaerobic, rod-shaped and non-motile bacterial strain, designated as 4C16AT, was isolated from a tidal flat sediment and characterized by using a polyphasic taxonomic approach. Strain 4C16AT was found to grow at 10–40 °C (optimum, 28 °C), at pH 5.0–10.0 (optimum, pH 6.0–7.0) and in 0–6 % (w/v) NaCl (optimum, 1 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 4C16AT fell into the genus Roseibium , and shared the highest identity of 98.9 % with the closest type strain Roseibium suaedae KACC 13772T and less than 98.0 % identity with other type strains of recognized species within this genus. The phylogenomic analysis indicated that strain 4C16AT formed an independent branch within this genus. The 28.6 % digital DNA–DNA hybridization estimate and 85.0 % average nucleotide identity between strains 4C16AT and R. suaedae KACC 13772T were the highest, but still far below their respective threshold for species definition, implying that strain 4C16AT should represent a novel genospecies. The predominant cellular fatty acid was summed feature 8; the polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmonomethylethanolamine; the respiratory quinones were Q-9 and Q-10. The genomic DNA G+C content was 59.8mol %. Based on phylogenetic analyses and phenotypic and chemotaxonomic characteristics, strain 4C16AT is concluded to represent a novel species of the genus Roseibium , for which the name Roseibium litorale sp. nov. is proposed. The type strain of the species is 4C16AT (=GDMCC 1.1932T=KACC 22078T). We also propose the reclassification of Labrenzia polysiphoniae as Roseibium polysiphoniae comb. nov. and ‘Labrenzia callyspongiae’ as Roseibium callyspongiae sp. nov.


Biomics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 106-137
Author(s):  
A.M. Sagitov ◽  
S.Yu. Zolkin ◽  
B.R. Kuluev ◽  
F.R. Gimalov ◽  
A.V. Knyazev ◽  
...  

When writing this botanical and historical review, it was necessary to get acquainted with the works of different authors from the XVII to the XXI century, written in Latin, old Spanish, old French, Spanish, French, German, Dutch, English and Russian. It shows the development of knowledge about growing on the American continents rubber-bearing trees, including their species definition and a botanical description. The main attention is paid to the Castilla elastica Cerv. from the Moraceae family, which served as a source of raw materials for the manufacture of an analogue of modern vulcanized rubber for ancient peoples of Mesoamerica and was then for many years the main rubber-bearing plant, whereas the priority have been given to Hevea brasiliensis (Wild. ex A. Juss.) Muell.-Arg. only after the beginning of plantation cultivation of this species in the end of XIX century. However, interest in Castilla did not completely disappear, and in the coming millennium, attempts were made to resume plantations. Sequencing of individual fragments of the nuclear and chloroplast genomes of Castilla species has also begun. The history of the appearance of the second erroneous name of this genus as Castilloa and the long process of returning the original name Castilla are described.


2020 ◽  
Vol 13 (1) ◽  
pp. 24-33
Author(s):  
Antonio Arnaiz-Villena ◽  
Valentín Ruiz-del-Valle ◽  
Fabio Suarez-Trujillo ◽  
Adrian Lopez-Nares ◽  
Alvaro Callado ◽  
...  

Introduction: South American siskins (Genus Carduelis/Spinus) are the outcome of regional evolutionary radiation from an extant (or other extinct) species: C. notata, a North America siskin, which thrives in Mexico subtropical areas and is parental of one of the three described North American siskin radiations. Methods: Speciation and/or subspeciation of this South American siskin radiation have probably occurred during Pleistocene Epoch. In the present paper, a new species/subspecies akin to C./S. atrata is described by genetic and phenotypic parameters: this new species/subspecies was previously considered a subspecies of C./S. xanthogastra, which thrives further North and is separated about 1,762 km, 1,094 miles, from this described subspecies, Carduelis/ Spinus xanthogastra stejnegeri. Results: Our genetic study using mt cyt b, phenotypic and behavior observations show that this putative C./S. xanthogastra subspecies is either a different species or a C./S. atrata subspecies; we have proposed a provisional name for this finch, C./S. lapazensis, instead of C./S. x. stejnegeri. Conclusion: Species definition is movable and controversial, and it is uncertain in South American siskins, which all show a close genetic and phenotypical relationship, which may be still immersed in speciation processes since Pleistocene Epoch.


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