Yersinia nurmii sp. nov
This study was set up to identify three Gram-negative, rod-shaped strains originating from broiler meat packaged under a modified atmosphere. A polyphasic taxonomic approach, including multilocus sequence analysis (MLSA) of five genes (16S rRNA, glnA, gyrB, recA and HSP60), DNA-DNA reassociation between the closest phylogenetic neighbours and determination of relevant phenotypic properties, was applied. Phylogenetic analysis of the 16S rRNA gene sequences grouped these strains together and within the genus Yersinia. MLSA of the 16S rRNA gene and four housekeeping genes showed that the strains formed a monophyletic group separate from other Yersinia species in all phylogenetic trees constructed. The strains had a phenotypic profile different from those of other representatives of the genus Yersinia, but most similar to that of Yersinia ruckeri. Typical virulence markers for pathogenic Yersinia were not detected. Based on phylogenetic, phenotypic and DNA-DNA reassociation data, a novel species, Yersinia nurmii sp. nov., is proposed for the isolated strains. The type strain is APN3a-c(T) ( = DSM 22296(T) = LMG 25213(T)).
Available from: Markku Kuusi
- "It is likely that the genetic difference between the two phylogenetic groups of Y. enterocolitica BT 1A discovered in the present study may also be high enough to justify designation of different subspecies or even species. Although further analyses would be needed for species designation, our data add insight into the phylogeny of the genus Yersinia, which is continuously evolving: three novel Yersinia species, Y. entomophaga, Y. pekkanenii and Y. nurmii were described as recently as 2010
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Y. enterocolitica biotype (BT) 1A strains are often isolated from human clinical samples but their contribution to disease has remained a controversial topic. Variation and the population structure among the clinical Y. enterocolitica BT 1A isolates have been poorly characterized. We used multi-locus sequence typing (MLST), 16S rRNA gene sequencing, PCR for ystA and ystB, lipopolysaccharide analysis, phage typing, human serum complement killing assay and analysis of the symptoms of the patients to characterize 298 clinical Y. enterocolitica BT 1A isolates in order to evaluate their relatedness and pathogenic potential.
A subset of 71 BT 1A strains, selected based on their varying LPS patterns, were subjected to detailed genetic analyses. The MLST on seven house-keeping genes (adk, argA, aroA, glnA, gyrB, thrA, trpE) conducted on 43 of the strains discriminated them into 39 MLST-types. By Bayesian analysis of the population structure (BAPS) the strains clustered conclusively into two distinct lineages, i.e. Genetic groups 1 and 2. The strains of Genetic group 1 were more closely related (97% similarity) to the pathogenic bio/serotype 4/O:3 strains than Genetic group 2 strains (95% similarity). Further comparison of the 16S rRNA genes of the BT 1A strains indicated that altogether 17 of the 71 strains belong to Genetic group 2. On the 16S rRNA analysis, these 17 strains were only 98% similar to the previously identified subspecies of Y. enterocolitica. The strains of Genetic group 2 were uniform in their pathogenecity-related properties: they lacked the ystB gene, belonged to the same LPS subtype or were of rough type, were all resistant to the five tested yersiniophages, were largely resistant to serum complement and did not ferment fucose. The 54 strains in Genetic group 1 showed much more variation in these properties. The most commonly detected LPS types were similar to the LPS types of reference strains with serotypes O:6,30 and O:6,31 (37%), O:7,8 (19%) and O:5 (15%).
The results of the present study strengthen the assertion that strains classified as Y. enterocolitica BT 1A represent more than one subspecies. Especially the BT 1A strains in our Genetic group 2 commonly showed resistance to human serum complement killing, which may indicate pathogenic potential for these strains. However, their virulence mechanisms remain unknown.
BMC Microbiology 09/2012; 12(1):208. DOI:10.1186/1471-2180-12-208 · 2.73 Impact Factor
Available from: Carina Brehony
- "Preliminary data indicates that the classical Yersinia species are not necessarily genetically homogenous, and isolates assigned to Yersinia enterocolitica, Yersinia frederiksenii, Yersinia kristensenii and Yersinia mollaretii have been found to belong to additional, previously unrecognized groups on the basis of multilocus sequence analysis (Kotetishvili et al., 2005). Recent updates on the taxonomy of Yersinia have recognized a total of 17 Yersinia species, three of which were first described in 2010 (Murros-Kontiainen et al., 2010a,b; Hurst et al., 2011). "
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ABSTRACT: Multilocus sequence analysis of 417 strains of Yersinia pseudotuberculosis revealed that it is a complex of four populations, three of which have been previously assigned species status [Y. pseudotuberculosis sensu stricto (s.s.), Yersinia pestis and Yersinia similis] and a fourth population, which we refer to as the Korean group, which may be in the process of speciation. We detected clear signs of recombination within Y. pseudotuberculosis s.s. as well as imports from Y. similis and the Korean group. The sources of genetic diversification within Y. pseudotuberculosis s.s. were approximately equally divided between recombination and mutation, whereas recombination has not yet been demonstrated in Y. pestis, which is also much more genetically monomorphic than is Y. pseudotuberculosis s.s. Most Y. pseudotuberculosis s.s. belong to a diffuse group of sequence types lacking clear population structure, although this species contains a melibiose-negative clade that is present globally in domesticated animals. Yersinia similis corresponds to the previously identified Y. pseudotuberculosis genetic type G4, which is probably not pathogenic because it lacks the virulence factors that are typical for Y. pseudotuberculosis s.s. In contrast, Y. pseudotuberculosis s.s., the Korean group and Y. pestis can all cause disease in humans.
Environmental Microbiology 09/2011; 13(12):3114-27. DOI:10.1111/j.1462-2920.2011.02588.x · 6.20 Impact Factor
Available from: PubMed Central
- "The genus Yersinia currently comprises three human pathogens (Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica), and at least 14 species considered harmless for humans, namely Y. aldovae, Y. bercovieri, Y. frederiksenii, Y. intermedia, Y. kristensenii, Y. mollaretii, Y. rohdei, Y. ruckeri , Y. aleksiciae , Y. similis , Y. massiliensis , Y. entomophaga , Y. nurmii  and Y. pekkanenii . Y. enterocolitica infection causes diarrhea, terminal ileitis, and mesenteric lymphadenitis, but not systemic infection, and often leads to secondary immunologically induced sequelae including erythema nodosum, reactive arthritis and Reiter's syndrome . "
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ABSTRACT: Yersinia enterocolitica strains responsible for mild gastroenteritis in humans are very diverse with respect to their metabolic and virulence properties. Strain W22703 (biotype 2, serotype O:9) was recently identified to possess nematocidal and insecticidal activity. To better understand the relationship between pathogenicity towards insects and humans, we compared the W22703 genome with that of the highly pathogenic strain 8081 (biotype1B; serotype O:8), the only Y. enterocolitica strain sequenced so far.
We used whole-genome shotgun data to assemble, annotate and analyse the sequence of strain W22703. Numerous factors assumed to contribute to enteric survival and pathogenesis, among them osmoregulated periplasmic glucan, hydrogenases, cobalamin-dependent pathways, iron uptake systems and the Yersinia genome island 1 (YGI-1) involved in tight adherence were identified to be common to the 8081 and W22703 genomes. However, sets of ~550 genes revealed to be specific for each of them in comparison to the other strain. The plasticity zone (PZ) of 142 kb in the W22703 genome carries an ancient flagellar cluster Flg-2 of ~40 kb, but it lacks the pathogenicity island YAPI(Ye), the secretion system ysa and yts1, and other virulence determinants of the 8081 PZ. Its composition underlines the prominent variability of this genome region and demonstrates its contribution to the higher pathogenicity of biotype 1B strains with respect to W22703. A novel type three secretion system of mosaic structure was found in the genome of W22703 that is absent in the sequenced strains of the human pathogenic Yersinia species, but conserved in the genomes of the apathogenic species. We identified several regions of differences in W22703 that mainly code for transporters, regulators, metabolic pathways, and defence factors.
The W22703 sequence analysis revealed a genome composition distinct from other pathogenic Yersinia enterocolitica strains, thus contributing novel data to the Y. enterocolitica pan-genome. This study also sheds further light on the strategies of this pathogen to cope with its environments.
BMC Genomics 03/2011; 12(1):168. DOI:10.1186/1471-2164-12-168 · 3.99 Impact Factor
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