Microbial genomic taxonomy

A need for a genomic species definition is emerging from several independent studies worldwide. In this commentary paper, we discuss recent studies on the genomic taxonomy of diverse microbial groups and a unified species definition based on genomics. Accordingly, strains from the same microbial species share >95% Average Amino Acid Identity (AAI) and Average Nucleotide Identity (ANI), >95% identity based on multiple alignment genes, 70% in silico Genome-to-Genome Hybridization similarity (GGDH). Species of the same genus will form monophyletic groups on the basis of 16S rRNA gene sequences, Multilocus Sequence Analysis (MLSA) and supertree analysis. In addition to the established requirements for species descriptions, we propose that new taxa descriptions should also include at least a draft genome sequence of the type strain in order to obtain a clear outlook on the genomic landscape of the novel microbe. The application of the new genomic species definition put forward here will allow researchers to use genome sequences to define simultaneously coherent phenotypic and genomic groups

Marinomonas brasilensis sp. nov., isolated from the coral Mussismilia hispida, and reclassification of Marinomonas basaltis as a later heterotypic synonym of Marinomonas communis

A Gram-negative, aerobic bacterium, designated strain R-40503(T), was isolated from mucus of the reef-builder coral Mussismilia hispida, located in the Sao Sebastiao Channel, Sao Paulo, Brazil. Phylogenetic analyses revealed that strain R-40503(T) belongs to the genus Marinomonas. The 16S rRNA gene sequence similarity of R-40503(T) was above 97% with the type strains of Marinomonas vaga, M. basaltis, M. communis and M. pontica, and below 97% with type strains of the other Marinomonas species. Strain R-40503(T) showed less than 35% DNA-DNA hybridization (DDH) with the type strains of the phylogenetically closest Marinomonas species, demonstrating that it should be classified into a novel species. Amplified fragment length polymorphism (AFLP), chemotaxonomic and phenotypic analyses provided further evidence for the proposal of a novel species. Concurrently, a close genomic relationship between M. basaltis and M. communis was observed. The type strains of these two species showed 78% DDH and 63% AFLP pattern similarity. Their phenotypic features were very similar, and their DNA G+C contents were identical (46.3 mol%). Collectively, these data demonstrate unambiguously that Marinomonas basaltis is a later heterotypic synonym of Marinomonas communis. Several phenotypic features can be used to discriminate between Marinomonas species. The novel strain R-40503(T) is clearly distinguishable from its neighbours. For instance, it shows oxidase and urease activity, utilizes L-asparagine and has the fatty acid C(12:1) 3-OH but lacks C(10:0) and C(12:0). The name Marinomonas brasilensis sp. nov. is proposed, with the type strain R-40503(T) (=R-278(T) =LMG 25434(T) =CAIM 1459(T)). The DNA G+C content of strain R-40503(T) is 46.5 mol%

Photobacterium sanctipauli sp nov isolated from bleached Madracis decactis (Scleractinia) in the St Peter & St Paul Archipelago, Mid-Atlantic Ridge, Brazil

Five novel strains of Photobacterium (A-394T, A-373, A-379, A-397 and A-398) were isolated from bleached coralMadracis decactis (scleractinian) in the remote St Peter & St Archipelago (SPSPA), Mid-Atlantic Ridge, Brazil. Healthy M. decactis specimens were also surveyed, but no strains were related to them. The novel isolates formed a distinct lineage based on the 16S rRNA, recA, and rpoA gene sequences analysis. Their closest phylogenetic neighbours were Photobacterium rosenbergii, P. gaetbulicola, and P. lutimaris, sharing 96.6 to 95.8% 16S rRNA gene sequence similarity. The novel species can be differentiated from the closest neighbours by several phenotypic and chemotaxonomic markers. It grows at pH 11, produces tryptophane deaminase, presents the fatty acid C-18:0, but lacks C-16:0 iso. The whole cell protein profile, based in MALDI-TOF MS, distinguished the strains of the novel species among each other and from the closest neighbors. In addition, we are releasing the whole genome sequence of the type strain. The name Photobacterium sanctipauli sp. nov. is proposed for this taxon. The G + C content of the type strain A-394(T) (=LMG27910(T) = CAIM1892(T)) is 48.2 mol%

Genomic and phenotypic attributes of novel salinivibrios from stromatolites, sediment and water from a high altitude lake

Background: Salinivibrios are moderately halophilic bacteria found in salted meats, brines and hypersaline environments. We obtained three novel conspecific Salinivibrio strains closely related to S. costicola, from Socompa Lake, a high altitude hypersaline Andean lake (approx. 3,570 meters above the sea level).Results: The three novel Salinivibrio spp. were extremely resistant to arsenic (up to 200 mM HAsO42-), NaCl (up to 15%), and UV-B radiation (19 KJ/m2, corresponding to 240 minutes of exposure) by means of phenotypic tests. Our subsequent draft genome ionsequencing and RAST-based genome annotation revealed the presence of genes related to arsenic, NaCl, and UV radiation resistance. The three novel Salinivibrio genomes also had the xanthorhodopsin gene cluster phylogenetically related to Marinobacter and Spiribacter. The genomic taxonomy analysis, including multilocus sequence analysis, average amino acid identity, and genome-to-genome distance revealed that the three novel strains belong to a new Salinivibrio species.Conclusions: Arsenic resistance genes, genes involved in DNA repair, resistance to extreme environmental conditions and the possible light-based energy production, may represent important attributes of the novel salinivibrios, allowing these microbes to thrive in the Socompa Lake. © 2014 Gorriti et al.; licensee BioMed Central Ltd.Fil: Gorriti, Marta Fabiana. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; ArgentinaFil: Dias, Graciela M.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; BrasilFil: Chimetto, Luciane A.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; BrasilFil: Trindade-Silva, Amaro E.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; BrasilFil: Silva, Bruno S.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; BrasilFil: Mesquita, Milene M.A.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; BrasilFil: Gregoracci, Gustavo B.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; BrasilFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; ArgentinaFil: Thompson, Cristiane C.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; BrasilFil: Thompson, Fabiano L.. Laboratório de Microbiologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil ; Brasi

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Quantitative Detection of Active Vibrios Associated with White Plague Disease in Mussismilia braziliensis Corals

Over recent decades several coral diseases have been reported as a significant threat to coral reef ecosystems causing the decline of corals cover and diversity around the world. The development of techniques that improve the ability to detect and quantify microbial agents involved in coral disease will aid in the elucidation of disease cause, facilitating coral disease detection and diagnosis, identification and pathogen monitoring, pathogen sources, vectors, and reservoirs. The genus Vibrio is known to harbor pathogenic strains to marine organisms. One of the best-characterized coral pathogens is Vibrio coralliilyticus, an aetilogic agent of White Plague Disease (WPD). We used Mussismilia coral tissue (healthy and diseased specimens) to develop a rapid reproducible detection system for vibrios based on RT-QPCR and SYBR chemistry. We were able to detect total vibrios in expressed RNA targeting the 16S rRNA gene at 5.23 × 10 6 copies/μg RNA and V. coralliilyticus targeting the pyrH gene at 5.10 × 10 3 copies/μg RNA in coral tissue. Detection of V. coralliilyticus in diseased and in healthy samples suggests that WPD in the Abrolhos Bank may be caused by a consortium of microorganism and not only a single pathogen. We developed a more practical and economic system compared with probe uses for the real-time detection and quantif ication of vibrios from coral tissues by using the 16S rRNA and pyrH gene. This qPCR assay is a reliable tool for the monitoring of coral pathogens, and can be useful to prevent, control, or reduce impacts in this ecosystem

Vibrios dominate as culturable nitrogen-fixing bacteria of the Brazilian coral mussismilia hispida

Taxonomic characterization was performed on the putative N2-fixing microbiota associated with the coral species Mussismilia hispida, and with its sympatric species Palythoa caribaeorum, P. variabilis, and Zoanthus solanderi, off the coast of São Sebastião (São Paulo State, Brazil). The 95 isolates belonged to the Gammaproteobacteria according to the 16S rDNA gene sequences. In order to identify the isolates unambiguously, pyrH gene sequencing was carried out. The majority of the isolates (n=76) fell within the Vibrio core group, with the highest gene sequence similarity being towards Vibrio harveyi and Vibrio alginolyticus. Nineteen representative isolates belonging to V. harveyi (n=7), V. alginolyticus (n=8), V. campbellii (n=3), and V. parahaemolyticus (n=1) were capable of growing six successive times in nitrogen-free medium and some of them showed strong nitrogenase activity by means of the acetylene reduction assay (ARA). It was concluded that nitrogen fixation is a common phenotypic trait among Vibrio species of the core group. The fact that different Vibrio species can fix N2 might explain why they are so abundant in the mucus of different coral species314312319CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão temNão temThe authors acknowledge grants from FAPESP, CNPq, FUJB and IFS. L.A. Chimetto acknowledges a PhD scholarship provided by CNPq. We would like to thank Mariza Gondo, Patrícia L. Ramos (ICB-USP), and Álvaro Migotto (CEBIMAR-USP) for technical assistance and valuable comment

Vibrios dominate as culturable nitrogen-fixing bacteria of the Brazilian coral Mussismilia hispida

Taxonomic characterization was performed on the putative N-2-fixing microbiota associated with the coral species Mussismilia hispida, and with its sympatric species Palythoa caribaeorum, P. variabilis, and Zoanthus solanderi, off the coast of Sao Sebastiao (Sao Paulo State, Brazil). The 95 isolates belonged to the Gammaproteobacteria according to the 16S rDNA gene sequences. In order to identify the isolates unambiguously, pyrH gene sequencing was carried out. The majority of the isolates (n = 76) fell within the Vibrio core group, with the highest gene sequence similarity being towards Vibrio harveyi and Vibrio alginolyticus. Nineteen representative isolates belonging to V. harveyi (n = 7), V. alginolyticus (n = 8), V. campbellii (n = 3), and V parahaemolyticus (n = 1) were capable of growing six successive times in nitrogen-free medium and some of them showed strong nitrogenase activity by means of the acetylene reduction assay (ARA). It was concluded that nitrogen fixation is a common phenotypic trait among Vibrio species of the core group. The fact that different Vibrio species can fix N, might explain why they are so abundant in the mucus of different coral species. (C) 2008 Published by Elsevier GmbH.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESPCNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FUJBFUJBIFSIF