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Wenliang Wu - One of the best experts on this subject based on the ideXlab platform.
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Identification of atpD as an optimal reference gene to explore antibiotic resistance and stress tolerance in Rahnella aquatilis
Journal of Applied Microbiology, 2019Co-Authors: Li Li, Junping Li, J. Peng, Wenliang WuAbstract:Rahnella aquatilis is a Gram-negative bacterial species with potential for agricultural and industrial applications, as well as a human pathogen. This study aims to identify an optimal reference gene to explore antibiotic resistance and stress tolerance in R. aquatilis using reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Expression levels of 14 housekeeping genes in R. aquatilis were estimated by RT-qPCR under six different conditions: exponential phase, stationary phase, acid, salinity, antibiotic and oxidative stresses. BestKeeper and the ΔCt method were used to evaluate the stability of each gene. The atpD gene was stably expressed in all conditions, thus was selected and validated as an optimal reference gene. Transcript levels of 17 putative ampicillin-resistance genes in R. aquatilis strain HX2 were evaluated using the proposed RT-qPCR. Six genes encoding efflux transporters and β-lactamase were overexpressed after ampicillin treatment. Additionally, the expression of seven putative stress response genes in strain HX2 was assessed, and five genes were up-regulated by respective stress treatments. The atpD gene has been identified as an optimal reference gene for expression analysis of R. aquatilis responses to abiotic stresses by RT-qPCR. The proposed RT-qPCR is suitable for gene expression analysis in R. aquatilis, thus useful for studying antimicrobial resistance and stress tolerance in this bacterium and others closely related. © 2019 The Society for Applied Microbiology.
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disruption of gene pqqa or pqqb reduces plant growth promotion activity and biocontrol of crown gall disease by Rahnella aquatilis hx2
PLOS ONE, 2014Co-Authors: Lei Li, Ziwei Jiao, Lauren Hale, Wenliang WuAbstract:Rahnella aquatilis strain HX2 has the ability to promote maize growth and suppress sunflower crown gall disease caused by Agrobacterium vitis, A. tumefaciens, and A. rhizogenes. Pyrroloquinoline quinone (PQQ), a cofactor of aldose and alcohol dehydrogenases, is required for the synthesis of an antibacterial substance, gluconic acid, by HX2. Mutants of HX2 unable to produce PQQ were obtained by in-frame deletion of either the pqqA or pqqB gene. In this study, we report the independent functions of pqqA and pqqB genes in relation to PQQ synthesis. Interestingly, both the pqqA and pqqB mutants of R. aquatilis eliminated the ability of strain HX2 to produce antibacterial substance, which in turn, reduced the effectiveness of the strain for biological control of sunflower crown gall disease. The mutation also resulted in decreased mineral phosphate solubilization by HX2, which reduced the efficacy of this strain as a biological fertilizer. These functions were restored by complementation with the wild-type pqq gene cluster. Additionally, the phenotypes of HX2 derivatives, including colony morphology, growth dynamic, and pH change of culture medium were impacted to different extents. Our findings suggested that pqqA and pqqB genes individually play important functions in PQQ biosynthesis and are required for antibacterial activity and phosphorous solubilization. These traits are essential for R. aquatilis efficacy as a biological control and plant growth promoting strain. This study enhances our fundamental understanding of the biosynthesis of an environmentally significant cofactor produced by a promising biocontrol and biological fertilizer strain.
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draft genome sequence of Rahnella aquatilis strain hx2 a plant growth promoting rhizobacterium isolated from vineyard soil in beijing china
Journal of Bacteriology, 2012Co-Authors: Ziwei Jiao, David E Crowley, Yongjun Wang, Lei Li, Wenliang WuAbstract:ABSTRACT Rahnella aquatilis strain HX2 is a plant growth-promoting, disease-suppressive rhizobacterium that was isolated from a vineyard soil in Beijing, China. Here, we report the genome sequence of this strain, which provides a valuable resource for future research examining the mechanisms of traits associated with plant growth promotion and biocontrol.
Thierry Heulin - One of the best experts on this subject based on the ideXlab platform.
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a major outer membrane protein of Rahnella aquatilis functions as a porin and root adhesin
Journal of Bacteriology, 1998Co-Authors: Wafa Achouak, Gerard Molle, Jean-marie Pagès, Thierry HeulinAbstract:A 38-kDa major outer membrane protein (OMP) was isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3. This protein exists as a stable trimer in the presence of 2% sodium dodecyl sulfate at temperatures below 60°C. Single channel experiments showed that this major OMP of R. aquatilis CF3 is able to form pores in the planar lipid membrane. Two oligonucleotides encoding the N-terminal portion of the 38-kDa OMP and C-terminal portion of OmpC were used to amplify the 38-kDa gene by PCR. The deduced amino acid sequence showed a strong homology with Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, and Serratia marcescens OmpC sequences, except loops L6 and L7, which are postulated to be cell surface exposed. On the basis of the OmpF-PhoE three-dimensional structure, it seems likely that this 38-kDa organizes three 16-strand b-barrel subunits. The relationship between the structure and the double functionality of this protein as porin and as a root adhesin is discussed. Rahnella aquatilis is a gram-negative enteric bacterium. It was isolated first from drinking and river water (15) and subsequently from human clinical specimens (27) and from the rhizospheres of different plants (5). R. aquatilis CF3 appears to lack fimbriae which could mediate the adhesive mechanism of other bacteria such as Klebsiella sp. (18). Since the R. aquatilis major outer membrane protein (OMP), which has an apparent molecular mass of 38 kDa, was shown to be involved in the adhesion of this organism to wheat roots (1), we consider OMPs to be important in the interaction between this R. aquatilis strain and roots of its host plant. The previously determined N-terminal amino acid sequence (1) indicates that this protein could be related to the enterobacterial porin family. These major OMPs are organized in a trimeric structure and are usually found in gram-negative bacteria (25). They form three water-filled channels that allow diffusion of small nutrients through the outer membrane (24). Porins might also be involved in other functions, such as those described during the invasion of epithelial cells by Salmonella typhimurium (9) and Shigella flexneri (6). We had previously reported that the N-terminal sequence of the major OMP (38 kDa) of R. aquatilis CF3 showed strong homology with enterobacterial porins (1). As this protein seems to be involved in the adhesion of R. aquatilis to plant roots (1), we sought to characterize it.
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purification and partial characterization of an outer membrane protein involved in the adhesion of Rahnella aquatilis to wheat roots
FEMS Microbiology Ecology, 1995Co-Authors: Wafa Achouak, Thierry HeulinAbstract:A 38 kDa major outer membrane protein isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3 showed high affinity for wheat roots in an in vitro adhesion assay. Antibodies directed against the 38 kDa protein were able to bind to whole cells of R. aquatilis and strongly reduced attachment to wheat roots, suggesting a role in adhesion to and colonization of plant roots. The N-terminal sequence of the 38 kDa protein revealed a strong homology with enterobacterial porins.
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Research articlePurification and partial characterization of an outer membrane protein involved in the adhesion of Rahnella aquatilis to wheat roots
FEMS Microbiology Ecology, 1995Co-Authors: Wafa Achouak, R. De Mot, Thierry HeulinAbstract:A 38 kDa major outer membrane protein isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3 showed high affinity for wheat roots in an in vitro adhesion assay. Antibodies directed against the 38 kDa protein were able to bind to whole cells of R. aquatilis and strongly reduced attachment to wheat roots, suggesting a role in adhesion to and colonization of plant roots. The N-terminal sequence of the 38 kDa protein revealed a strong homology with enterobacterial porins.
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bacillus polymyxa and Rahnella aquatilis the dominant n2 fixing bacteria associated with wheat rhizosphere in french soils
European Journal of Soil Biology, 1994Co-Authors: Thierry Heulin, Odile Berge, L Gouzou, K.p. Hebbar, Patrick Mavingui, Jacques BalandreauAbstract:Au cours d'une etude sur les bacteries fixatrices d'azote adaptees a la rhizosphere des plantes, nous avons isole 56 souches bacteriennes representatives de la rhizosphere d'un ble de printemps (cv. Castan) ayant atteint le stade trois feuilles. L'etape d'isolement a ete realisee par enrichissement en presence d'exsudats produits par de jeunes plantules de ble germant sterilement (technique du «modele spermosphere»). Bacillus polymyxa et Bacillus circulans sont les especes fixatrices d'azote les plus frequentes dans trois des quatre sols etudies. Dans le quatrieme sol, l'espece fixatrice d'azote dominante est Rahnella aquatilis, qui est une enterobacterie taxonomiquement proche de Enterobacter agglomerans et Erwinia herbicola (.)
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Bacillus polymyxa and Rahnella aquatilis, the dominant N2-fixing bacteria associated with wheat roots in French soils
European Journal of Soil Biology, 1994Co-Authors: Thierry Heulin, Odile Berge, K.p. Hebbar, Patrick Mavingui, L. Gouzoux, Jacques BalandreauAbstract:In a study of adaptive traits of rhizosphere inhabiting N2-fixing bacteria, 56 strains representative for the diazotrophic population were isolated from the rhizosphere of three week old spring wheat plants (cv. Castan). For the isolation procedure, a medium was used which contained the exudates of sterile plantlets of wheat (the ''spermosphere model''). N2-fixing Bacillus polymyxa and Bacillus circulans were dominant in three out of four French soils studied. The dominant N2-fixing microflora of the fourth soil was a population of Rahnella aquatilis, an enteric bacterium closely related to Enterobacter agglomerans and Erwinia herbicola. The sizes of these N2-fixing populations were between 1 and 5 x 10(5) cfu g-1 dry weight of rhizosphere soil. These two rhizosphere populations differed markedly by two important characters: (1) when associated with plants under gnotobiotic conditions, the average acetylene reduction activity was much higher in Bacillus than in R. aquatilis strains; (2) in vitro, 90% of Bacillus isolates exhibited a clear antagonistic activity against Gaeumannomyces graminis var. tritici (Ggt), the causative agent of the take-all disease of wheat, whereas none of the 25 strains of R. aquatilis tested showed any antogonistic activity.
Evelina L. Zdorovenko - One of the best experts on this subject based on the ideXlab platform.
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Rahnella aquatilis 95u003 lipopolysaccharide
Microbiology, 2010Co-Authors: L D Varbanets, L. B. Skoklyuk, V. V. Shubchynskyy, Evelina L. Zdorovenko, S. I. PokhilAbstract:The lipopolysaccharide of a new species of Enterobacteriaceae, Rahnella aquatilis 95U003, was isolated and investigated. The structural components of the lipopolysaccharide molecule, lipid A, core oligosaccharide, and O-specific polysaccharide, were isolated by mild acidic hydrolysis. In lipid A, 3-hydroxytetradecanoic (64.3%) and tetradecanoic (22.3%) acids were found to be predominant fatty acids. In fractions 1 and 2 of the core oligosaccharides, galactose (36.6 and 43.6%), mannose (35.5 and 23.5%), and glucose (42.1 and 25.3%) were shown to be the major monosaccharides. The O-specific polysaccharide consisted of regularly repeating hexasaccharide units of the following structure: Open image in new window
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Rahnella aquatilis 95U003 lipopolysaccharide
Microbiology, 2010Co-Authors: L D Varbanets, L. B. Skoklyuk, V. V. Shubchynskyy, Evelina L. Zdorovenko, S. I. PokhilAbstract:The lipopolysaccharide of a new species of Enterobacteriaceae, Rahnella aquatilis 95U003, was isolated and investigated. The structural components of the lipopolysaccharide molecule, lipid A, core oligosaccharide, and O-specific polysaccharide, were isolated by mild acidic hydrolysis. In lipid A, 3-hydroxytetradecanoic (64.3%) and tetradecanoic (22.3%) acids were found to be predominant fatty acids. In fractions 1 and 2 of the core oligosaccharides, galactose (36.6 and 43.6%), mannose (35.5 and 23.5%), and glucose (42.1 and 25.3%) were shown to be the major monosaccharides. The O-specific polysaccharide consisted of regularly repeating hexasaccharide units of the following structure:
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isolation and structure elucidation of two different polysaccharides from the lipopolysaccharide of Rahnella aquatilis 33071t
Carbohydrate Research, 2009Co-Authors: Evelina L. Zdorovenko, L D Varbanets, G. M. Zdorovenko, Georgy V. Zatonsky, Alexander S Shashkov, Yuriy A KnirelAbstract:Abstract Two different polysaccharides were obtained by mild acid degradation of the lipopolysaccharide of Rahnella aquatilis 33071 T . These were studied by sugar and methylation analyses along with 1D and 2D 1 H and 13 C NMR spectroscopy. The following structures were established for the polysaccharides: Download full-size image The former structure is new, whereas the latter has been reported earlier as the structure of the O-specific polysaccharide of R. aquatilis 95 U003 (Zdorovenko, E. L.; Varbanets, L. D.; Zatonsky, G. V.; Kachala, V. V.; Zdorovenko, G. M.; Shashkov, A. S.; Knirel, Y. A. Carbohydr. Res. 2008 , 343 , 2494–2497).
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structure of the o specific polysaccharide of the lipopolysaccharide of Rahnella aquatilis 95 u003
Carbohydrate Research, 2008Co-Authors: Evelina L. Zdorovenko, L D Varbanets, G. M. Zdorovenko, Vadim V. Kachala, Georgy V. Zatonsky, Alexander S Shashkov, Yuriy A KnirelAbstract:Abstract The O-polysaccharide of Rahnella aquatilis 95 U003 was obtained by mild acid degradation of the lipopolysaccharide and studied by sugar and methylation analyses, Smith degradation and 1 H and 13 C NMR spectroscopy, including 2D 1 H, 1 H COSY, TOCSY, ROESY, H-detected 1 H, 13 C HSQC and HMQC-TOCSY experiments. The O-polysaccharide was found to have a branched hexasaccharide repeating unit of the following structure: Download full-size image
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chemical characteristics and endotoxic activity of the lipopolysaccharide of Rahnella aquatilis 2 95
Microbiology, 2008Co-Authors: L D Varbanets, Evelina L. Zdorovenko, Andrey N OstapchukAbstract:The lipopolysaccharide (LPS) from a new Enterobacteriaceae species, Rahnella aquatilis 2-95, was isolated and investigated. The structural components of the LPS molecule, namely, lipid A, core oligosaccharide, and O-specific polysaccharide, were obtained by mild acid hydrolysis. In lipid A, 3-oxytetradecanoic and tetradecanoic acids were found to be the predominant fatty acids. The major monosaccharides of the core oligosaccharide were galactose, arabinose, fucose, rhamnose, and an unidentified component. The O-specific polysaccharide was found to be assembled of a repeated trisaccharide unit of the following structure: Open image in new window The R. aquatilis 2-95 LPS is less toxic and more pyrogenic than the LPS from the R. aquatilis 1-95 strain studied earlier. Both acyl and phosphate groups are essential for toxic and pyrogenic activity of R. aquatilis 2-95 LPS.
Li Li - One of the best experts on this subject based on the ideXlab platform.
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Identification of atpD as an optimal reference gene to explore antibiotic resistance and stress tolerance in Rahnella aquatilis
Journal of Applied Microbiology, 2019Co-Authors: Li Li, Junping Li, J. Peng, Wenliang WuAbstract:Rahnella aquatilis is a Gram-negative bacterial species with potential for agricultural and industrial applications, as well as a human pathogen. This study aims to identify an optimal reference gene to explore antibiotic resistance and stress tolerance in R. aquatilis using reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Expression levels of 14 housekeeping genes in R. aquatilis were estimated by RT-qPCR under six different conditions: exponential phase, stationary phase, acid, salinity, antibiotic and oxidative stresses. BestKeeper and the ΔCt method were used to evaluate the stability of each gene. The atpD gene was stably expressed in all conditions, thus was selected and validated as an optimal reference gene. Transcript levels of 17 putative ampicillin-resistance genes in R. aquatilis strain HX2 were evaluated using the proposed RT-qPCR. Six genes encoding efflux transporters and β-lactamase were overexpressed after ampicillin treatment. Additionally, the expression of seven putative stress response genes in strain HX2 was assessed, and five genes were up-regulated by respective stress treatments. The atpD gene has been identified as an optimal reference gene for expression analysis of R. aquatilis responses to abiotic stresses by RT-qPCR. The proposed RT-qPCR is suitable for gene expression analysis in R. aquatilis, thus useful for studying antimicrobial resistance and stress tolerance in this bacterium and others closely related. © 2019 The Society for Applied Microbiology.
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biosynthesis of selenium nanoparticles and effects of selenite selenate and selenomethionine on cell growth and morphology in Rahnella aquatilis hx2
Applied Microbiology and Biotechnology, 2018Co-Authors: Huafen Li, Li Li, Gary S Banuelos, Guishen ZhaoAbstract:Rahnella aquatilis HX2 (proteobacteria) shows tolerance to selenium (Se). The minimum inhibitory concentrations of selenomethionine (Se-Met), selenite [Se (IV)], and selenate [Se (VI)] to HX2 are 4.0, 85.0, and 590.0 mM, respectively. HX2 shows the ability to reduce Se (IV) and Se (VI) to elemental Se nanoparticles (SeNPs). The maximum production of SeNPs by HX2 strain is 1.99 and 3.85 mM in Luria-Bertani (LB) broth with 5 mM Se (IV) and 10 mM Se (VI), respectively. The morphology of SeNPs and cells were observed by transmission electron microscope, environmental scanning electron microscope, and selected area electric diffraction detector. Spherical SeNPs with amorphous structure were found in the cytoplasm, membrane, and exterior of cells. Morphological variations of the cell membrane were further confirmed by the release of cellular materials absorbed at 260 nm. Flagella were inhibited and cell sizes were 1.8-, 1.6-, and 1.2-fold increases with the Se-Met, Se (VI), and Se (IV) treatments, respectively. The real-time quantitative PCR analysis indicated that some of the genes controlling Se metabolism or cell morphology, including cysA, cysP, rodA, ZntA, and ada, were significantly upregulated, while grxA, fliO, flgE, and fliC genes were significantly downregulated in those Se treatments. This study provided novel valuable information concerning the cell morphology along with biological synthesis process of SeNPs in R. aquatilis and demonstrated that the strain HX2 could be applied in both biosynthesis of SeNPs and in management of environmental Se pollution.
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first report of Rahnella aquatilis infection in crucian carp carassius auratus in china
Diseases of Aquatic Organisms, 2017Co-Authors: Aijun Lu, Xiucai Hu, Li Li, Ruixia Wang, Chao ZhangAbstract:Rahnella aquatilis infection is rare in aquaculture. Here, a Gram-negative rod-shaped bacterium was isolated from diseased crucian carp Carassius auratus in Xuzhou City, Jiangsu Province, eastern China. The isolate was tentatively named strain KCL-5, and subsequently identified as R. aquatilis by biochemical properties and molecular techniques. The results showed that the isolate KCL-5 was most closely related to the type strain ATCC33071 (= DSM4594) of R. aquatilis, which shared 99.67, 96.26 and 99.58% nucleotide sequence identities for 16S rDNA, gyrB and toxin yhaV genes, respectively. Experimental challenges were conducted which demonstrated pathogenicity of the isolate in crucian carp. Antimicrobial susceptibility testing showed that the isolated strain was susceptible to piperacillin, gentamicin, kanamycin, nalidixic acid, norfloxacin, ofloxacin, azithromycin and erythromycin. To our knowledge, this is the first report on R. aquatilis infection in crucian carp, and the first evidence of pathogenicity in fish.
L D Varbanets - One of the best experts on this subject based on the ideXlab platform.
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biological activity of native and modified lipopolysaccharides Rahnella aquatilis
Mikrobiolohichnyĭ zhurnal, 2011Co-Authors: L B Skokliuk, L D Varbanets, N. V. ShmatkovaAbstract:The results of the comparative toxicity studies of native lipopolysaccharide (LPS) of Rahnella aquatilis 96U037 and that modified by tin complexes indicates that, due to the modification of LPS by tin complex with benzoylhydrazone of 4-dimethylaminobenzaldehyde, a decrease of its toxicity was observed that led to disappearance of the pyrogenic effect. All obtained derivatives lost completely the antigenic activity both in homologous and heterologous systems which may indicate to the interaction of modifying complexes with certain groups being the components of antigenic determinant. The paper is presented in Ukrainian.
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Rahnella aquatilis 95u003 lipopolysaccharide
Microbiology, 2010Co-Authors: L D Varbanets, L. B. Skoklyuk, V. V. Shubchynskyy, Evelina L. Zdorovenko, S. I. PokhilAbstract:The lipopolysaccharide of a new species of Enterobacteriaceae, Rahnella aquatilis 95U003, was isolated and investigated. The structural components of the lipopolysaccharide molecule, lipid A, core oligosaccharide, and O-specific polysaccharide, were isolated by mild acidic hydrolysis. In lipid A, 3-hydroxytetradecanoic (64.3%) and tetradecanoic (22.3%) acids were found to be predominant fatty acids. In fractions 1 and 2 of the core oligosaccharides, galactose (36.6 and 43.6%), mannose (35.5 and 23.5%), and glucose (42.1 and 25.3%) were shown to be the major monosaccharides. The O-specific polysaccharide consisted of regularly repeating hexasaccharide units of the following structure: Open image in new window
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Rahnella aquatilis 95U003 lipopolysaccharide
Microbiology, 2010Co-Authors: L D Varbanets, L. B. Skoklyuk, V. V. Shubchynskyy, Evelina L. Zdorovenko, S. I. PokhilAbstract:The lipopolysaccharide of a new species of Enterobacteriaceae, Rahnella aquatilis 95U003, was isolated and investigated. The structural components of the lipopolysaccharide molecule, lipid A, core oligosaccharide, and O-specific polysaccharide, were isolated by mild acidic hydrolysis. In lipid A, 3-hydroxytetradecanoic (64.3%) and tetradecanoic (22.3%) acids were found to be predominant fatty acids. In fractions 1 and 2 of the core oligosaccharides, galactose (36.6 and 43.6%), mannose (35.5 and 23.5%), and glucose (42.1 and 25.3%) were shown to be the major monosaccharides. The O-specific polysaccharide consisted of regularly repeating hexasaccharide units of the following structure:
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chemical characterisation of structural components of Rahnella aquatilis lipopolysaccharides
Mikrobiolohichnyĭ zhurnal, 2010Co-Authors: L B Skokliuk, L D VarbanetsAbstract:The studies of lipopolysaccharides (LPS) of eight Rahnella aquatilis strains, isolated from different sources have shown that they contain both S- and R-types of molecules. This fact is evidenced by the presence of high-molecular fraction of O-specific polysaccharides (O-PS) and low-molecular fraction of core oligosaccharides. The predominant monosaccharides of core oligosaccharides were glucose, galactose. The presence of only one high-molecular fraction O-PS was a characteristic feature of all investigated strains. The predominant monosaccharides of O-PS were galactose, glucose, mannose, rhamnose and fucose. 3-hydroxytetradecanoic (48.9-93.1%), dodecanoic (2.9-12.1%), tetradecanoic (4.1-25.3%) and hexadecanoic (2.8-15.3%) acids have been obtained in lipids A of LPS depending on the strain. The presence in lipid A of R. aquatilis of only 3-hydroxytetradecanoic acid which is characteristic of Enterobacteriaceae proves the correct ascribing of the isolated strains to this family.
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isolation and structure elucidation of two different polysaccharides from the lipopolysaccharide of Rahnella aquatilis 33071t
Carbohydrate Research, 2009Co-Authors: Evelina L. Zdorovenko, L D Varbanets, G. M. Zdorovenko, Georgy V. Zatonsky, Alexander S Shashkov, Yuriy A KnirelAbstract:Abstract Two different polysaccharides were obtained by mild acid degradation of the lipopolysaccharide of Rahnella aquatilis 33071 T . These were studied by sugar and methylation analyses along with 1D and 2D 1 H and 13 C NMR spectroscopy. The following structures were established for the polysaccharides: Download full-size image The former structure is new, whereas the latter has been reported earlier as the structure of the O-specific polysaccharide of R. aquatilis 95 U003 (Zdorovenko, E. L.; Varbanets, L. D.; Zatonsky, G. V.; Kachala, V. V.; Zdorovenko, G. M.; Shashkov, A. S.; Knirel, Y. A. Carbohydr. Res. 2008 , 343 , 2494–2497).