<i>Brevundimonas halotolerans</i> sp. nov., <i>Brevundimonas poindexterae</i> sp. nov. and <i>Brevundimonas staleyi</i> sp. nov., prosthecate bacteria from aquatic habitats

Eight strains of Gram-negative, bacteroid-shaped, prosthecate bacteria, isolated from brackish water (MCS24T, MCS17 and MCS35), the marine environment (CM260, CM272 and CM282) and activated sludge (FWC40T and FWC43T), were characterized using a polyphasic approach. Analysis of 16S rRNA gene sequences determined that all strains were affiliated to the alphaproteobacterial genus Brevundimonas, forming three distinct phyletic lineages within the genus. The strains grew best with 5–30 g NaCl l-1 at 20–30 °C. DNA G+C contents for strains MCS24T, FWC40T and FWC43T were between 65 and 67 mol%, in accordance with values reported previously for other species of the genus. Moreover, chemotaxonomic data and physiological and biochemical tests allowed the phenotypic differentiation of three novel species within the genus Brevundimonas, for which the names Brevundimonas halotolerans sp. nov. (type strain MCS24T =LMG 25346T =CCUG 58273T), Brevundimonas poindexterae sp. nov. (type strain FWC40T =LMG 25261T =CCUG 57883T) and Brevundimonas staleyi sp. nov. (type strain FWC43T =LMG 25262T =CCUG 57884T) are proposed

<i>Echinicola vietnamensis</i> sp. nov., a member of the phylum <i>Bacteroidetes</i> isolated from seawater

The taxonomic position of a novel marine, heterotrophic, gliding, halotolerant and light-pink-pigmented bacterium, designated strain KMM 6221T, was examined by using a polyphasic approach. 16S rRNA gene sequence analysis indicated that strain KMM 6221T is affiliated with the genus Echinicola, a member of the phylum Bacteroidetes, with levels of similarity of 94.7–95.0 % to strains of Echinicola pacifica. Growth of strain KMM 6221T was observed with 0–15 % NaCl and at 6–44 °C. The DNA G+C content of strain KMM 6221T was 45.9 mol%. On the basis of molecular distinctiveness supported by phenotypic and chemotaxonomic data, strain KMM 6221T is considered to represent a novel species of the genus Echinicola, for which the name Echinicola vietnamensis sp. nov. is proposed. The type strain is KMM 6221T (=DSM 17526T=LMG 23754T)

<i>Sneathiella chinensis</i> gen. nov., sp. nov., a novel marine alphaproteobacterium isolated from coastal sediment in Qingdao, China

The taxonomic position of strain LMG 23452T, which was isolated from coastal sediment from an aquaculture site near Qingdao, China, in 2000, was determined. Strain LMG 23452T comprised Gram-negative, non-spore-forming, motile rods and was found to be a halotolerant, aerobic, chemoheterotroph that produces catalase and oxidase. Comparative 16S rRNA gene sequence analysis revealed that strain LMG 23452T shared approximately 89 % sequence similarity with members of the genera Devosia, Hyphomonas, Ensifer and Chelatococcus, which belong to two different orders within the Alphaproteobacteria. Further phylogenetic analysis of the 16S rRNA gene sequence showed that strain LMG 23452T formed a separate branch within the order Rhizobiales, falling between the genera Devosia and Ensifer of the families Hyphomicrobiaceae and Rhizobiaceae, respectively. Strain LMG 23452T could be differentiated from its closest phylogenetic neighbours on the basis of several phenotypic features, including hydrolysis of the substrates starch and casein and assimilation of the carbohydrates d-glucose, d-mannose, mannitol, maltose and l-arabinose, and chemotaxonomically by the presence of the fatty acids C14 : 0 3-OH, C16 : 1ω11c, C16 : 1 ω5c and C18 : 1ω5c. The major fatty acids detected in strain LMG 23452T were C18 : 1 ω7c, C16 : 0, C19 : 0 cyclo ω8c, C16 : 1 ω7c and C17 : 1ω6c and the G+C content of the genomic DNA was 57.1 mol%. Therefore, the polyphasic data support the placement of strain LMG 23452T within a novel genus and species, for which the name Sneathiella chinensis gen. nov., sp. nov. is proposed. The type strain is LMG 23452T (=CBMAI 737T)

Enterococcus devriesei sp. nov., associated with animal sources

http://ijs.sgmjournals.org/The taxonomic position of two bovine strains, LMG 13603 and LMG 14595, assigned to the species Enterococcus raffinosus on the basis of biochemical features, was reinvestigated. Both reference strains and two other isolates, 6/1 (=LMG 22829) originating from a charcoal-broiled river lamprey and IE38.4 (=LMG 22830) from the air of a poultry slaughter by-product processing plant, occupied a clearly separate position, on the basis of sequence analysis of the housekeeping gene pheS (encoding the phenylalanyl-tRNA synthase a-subunit), relative to the type strain of E. raffinosus and all other enterococcal species with validly published names. 16S rRNA gene sequencing of strains LMG 13603, LMG 14595, 6/1 and IE38.4 confirmed their phylogenetic position in the Enterococcus avium species group, there being more than 99% 16S rRNA gene sequence similarity to most members of the group, including E. raffinosus, and revealed Enterococcus pseudoavium as the closest phylogenetic relative (99,8–99,9 %). Further phenotypic and genotypic analyses using whole-cell-protein electrophoresis, (GTG)5-PCR fingerprinting, ribotyping and DNA–DNA hybridization experiments demonstrated that all four strains represent a novel enterococcal species, for which the name Enterococcus devriesei sp. nov. is proposed. The type strain is LMG 14595T (=CCM 7299T)

Влияние интенсивности механической активации на структуру гексагонального нитрида бора

Изучено влияние интенсивности механической активации на микроструктуру и свойства гексагонального нитрида бора (hBN).Вивчено вплив інтенсивності механічної активації на мікроструктуру і властивості гексагонального нітриду бору (hBN).The mechanical activation intensity effect on the microstructure and properties of hexagonal boron nitride (hBN) has been studied

Epidemic and Nonepidemic Multidrug-Resistant Enterococcus faecium

The epidemiology of vancomycin-resistant Enterococcus faecium (VREF) in Europe is characterized by a large community reservoir. In contrast, nosocomial outbreaks and infections (without a community reservoir) characterize VREF in the United States. Previous studies demonstrated host-specific genogroups and a distinct genetic lineage of VREF associated with hospital outbreaks, characterized by the variant esp-gene and a specific allele-type of the purK housekeeping gene (purK1). We investigated the genetic relatedness of vanA VREF (n=108) and vancomycin-susceptible E. faecium (VSEF) (n=92) from different epidemiologic sources by genotyping, susceptibility testing for ampicillin, sequencing of purK1, and testing for presence of esp. Clusters of VSEF fit well into previously described VREF genogroups, and strong associations were found between VSEF and VREF isolates with resistance to ampicillin, presence of esp, and purK1. Genotypes characterized by presence of esp, purK1, and ampicillin resistance were most frequent among outbreak-associated isolates and almost absent among community surveillance isolates. Vancomycin-resistance was not specifically linked to genogroups. VREF and VSEF from different epidemiologic sources are genetically related; evidence exists for nosocomial selection of a subtype of E. faecium, which has acquired vancomycin-resistance through horizontal transfer

Differential Metabolisms of Green Leaf Volatiles in Injured and Intact Parts of a Wounded Leaf Meet Distinct Ecophysiological Requirements

Almost all terrestrial plants produce green leaf volatiles (GLVs), consisting of six-carbon (C6) aldehydes, alcohols and their esters, after mechanical wounding. C6 aldehydes deter enemies, but C6 alcohols and esters are rather inert. In this study, we address why the ability to produce various GLVs in wounded plant tissues has been conserved in the plant kingdom. The major product in completely disrupted Arabidopsis leaf tissues was (Z)-3-hexenal, while (Z)-3-hexenol and (Z)-3-hexenyl acetate were the main products formed in the intact parts of partially wounded leaves. 13C-labeled C6 aldehydes placed on the disrupted part of a wounded leaf diffused into neighboring intact tissues and were reduced to C6 alcohols. The reduction of the aldehydes to alcohols was catalyzed by an NADPH-dependent reductase. When NADPH was supplemented to disrupted tissues, C6 aldehydes were reduced to C6 alcohols, indicating that C6 aldehydes accumulated because of insufficient NADPH. When the leaves were exposed to higher doses of C6 aldehydes, however, a substantial fraction of C6 aldehydes persisted in the leaves and damaged them, indicating potential toxicity of C6 aldehydes to the leaf cells. Thus, the production of C6 aldehydes and their differential metabolisms in wounded leaves has dual benefits. In disrupted tissues, C6 aldehydes and their α,β-unsaturated aldehyde derivatives accumulate to deter invaders. In intact cells, the aldehydes are reduced to minimize self-toxicity and allow healthy cells to survive. The metabolism of GLVs is thus efficiently designed to meet ecophysiological requirements of the microenvironments within a wounded leaf

Experimental evidence for splicing of intron-containing transcripts of plant LTR retrotransposon Ogre

Ogre elements are a distinct group of plant Ty3/gypsy-like retrotransposons characterized by several specific features, one of which is a separation of the gag-pol region into two non-overlapping open reading frames: ORF2 coding for Gag-Pro, and ORF3 coding for RT/RH-INT proteins. Previous characterization of Ogre elements from several plant species revealed that part of their transcripts lacks the region between ORF2 and ORF3, carrying one uninterrupted ORF instead. In this work, we investigated a hypothesis that this region represents an intron that is spliced out from part of the Ogre transcripts as a means for preferential production of ORF2-encoded proteins over those encoded by the complete ORF2–ORF3 region. The experiments involved analysis of transcription patterns of well-defined Ogre populations in a model plant Medicago truncatula and examination of transcripts carrying dissected pea Ogre intron expressed within a coding sequence of chimeric reporter gene. Both experimental approaches proved that the region between ORF2 and ORF3 is spliced from Ogre transcripts and showed that this process is only partial, probably due to weak splice signals. This is one of very few known cases of spliced LTR retrotransposons and the only one where splicing does not involve parts of the element’s coding sequences, thus resembling intron splicing found in most cellular genes

Intraspecies Genomic Groups in Enterococcus faecium and Their Correlation with Origin and Pathogenicity

http://aem.asm.org/Seventy-eight Enterococcus faecium strains from various sources were characterized by random amplified polymorphic DNA (RAPD)-PCR, amplified fragment length polymorphism (AFLP), and pulsed-field gel electrophoresis (PFGE) analysis of SmaI restriction patterns. Two main genomic groups (I and II) were obtained in both RAPD-PCR and AFLP analyses. DNA-DNA hybridization values between representative strains of both groups demonstrated a mean DNA-DNA reassociation level of 71%. PFGE analysis revealed high genetic strain diversity within the two genomic groups. Only group I contained strains originating from human clinical samples or strains that were vancomycin-resistant or beta-hemolytic. No differentiating phenotypic features between groups I and II were found using the rapid ID 32 STREP system. The two groups could be further subdivided into, respectively, four and three subclusters in both RAPD-PCR and AFLP analyses, and a high correlation was seen between the subclusters generated by these two methods. Subclusters of group I were to some extent correlated with origin, pathogenicity, and bacteriocinogeny of the strains. Host specificity of E. faecium strains was not confirmed

From learning taxonomies to phylogenetic learning: Integration of 16S rRNA gene data into FAME-based bacterial classification

<p>Abstract</p> <p>Background</p> <p>Machine learning techniques have shown to improve bacterial species classification based on fatty acid methyl ester (FAME) data. Nonetheless, FAME analysis has a limited resolution for discrimination of bacteria at the species level. In this paper, we approach the species classification problem from a taxonomic point of view. Such a taxonomy or tree is typically obtained by applying clustering algorithms on FAME data or on 16S rRNA gene data. The knowledge gained from the tree can then be used to evaluate FAME-based classifiers, resulting in a novel framework for bacterial species classification.</p> <p>Results</p> <p>In view of learning in a taxonomic framework, we consider two types of trees. First, a FAME tree is constructed with a supervised divisive clustering algorithm. Subsequently, based on 16S rRNA gene sequence analysis, phylogenetic trees are inferred by the NJ and UPGMA methods. In this second approach, the species classification problem is based on the combination of two different types of data. Herein, 16S rRNA gene sequence data is used for phylogenetic tree inference and the corresponding binary tree splits are learned based on FAME data. We call this learning approach 'phylogenetic learning'. Supervised Random Forest models are developed to train the classification tasks in a stratified cross-validation setting. In this way, better classification results are obtained for species that are typically hard to distinguish by a single or flat multi-class classification model.</p> <p>Conclusions</p> <p>FAME-based bacterial species classification is successfully evaluated in a taxonomic framework. Although the proposed approach does not improve the overall accuracy compared to flat multi-class classification, it has some distinct advantages. First, it has better capabilities for distinguishing species on which flat multi-class classification fails. Secondly, the hierarchical classification structure allows to easily evaluate and visualize the resolution of FAME data for the discrimination of bacterial species. Summarized, by phylogenetic learning we are able to situate and evaluate FAME-based bacterial species classification in a more informative context.</p