A novel symbiotic nitrogen-fixing member of the Ochrobactrum clade isolated from root nodules of Acacia mangium.
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Ten strains of root nodule bacteria were isolated from the nodules of Acacia mangium grown in the Philippines and Thailand. Partial sequences (approx. 300 bp) of the 16S rRNA gene of each isolate were analyzed. The nucleotide sequences of strain DASA 35030 indicated high homology (>99%) with members of the genus Ochrobactrum in Brucellaceae, although the sequences of other isolates were homologous to those of two distinct genera Bradyrhizobium and Rhizobium. The strain DASA 35030 was strongly suggested to be a strain of Ochrobactrum by full length sequences of the 16S rRNA gene, fatty acids composition, G+C contents of the DNA, and other physiological characteristics. Strain DASA 35030 induced root nodules on A. mangium, A. albida and Paraserianthes falcataria. The nodules formed by strain DASA 35030 fixed nitrogen and the morphology of the nodules is the same as those of nodules formed by the other isolates. This is the first report that the strain of Ochrobactrum possesses complete symbiotic ability with Acacia. (+info)
Interaction of endotoxins with Toll-like receptor 4 correlates with their endotoxic potential and may explain the proinflammatory effect of Brucella spp. LPS.
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Endotoxins displaying differences in the chemical structure of their lipid A were used to induce the expression of chemokines in the human monocytic THP-1 cell line. LPS from two enterobacterial species such as Escherichia coli and Yersinia enterocolitica induced mRNA expression of IFN-gamma-inducible protein (IP)-10, macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, monocyte chemoattractant protein (MCP)-1 and IL-8. LPS from the non-enterobacterial genera Brucella and Ochrobactrum induced the expression of these chemokines to a lower extent. Attempts to address the signaling routes involved in these responses were carried out in transiently transfected HEK293 cells. Induction of kappaB-driven transcriptional activity by enterobacterial LPS was observed in cells transfected with TLR-4 alone, although co-transfection of TLR-4, MD-2 and CD14 provided optimal induction. The response to Brucella spp. and Ochrobactrum anthropi LPS was only significant at the concentration of 10 microg/ml. These data indicate that LPS from Brucella spp. and O. anthropi, which contain lipid A moieties with structural features different from those of Enterobacteriaceae elicit biochemical signaling via TLR-4 only at high concentrations. Neither TLR-1, TLR-2 and TLR-6 nor heterodimeric combinations of these receptor molecules are involved. Conversely, the ability of LPS to activate the TLR-4 route is a reliable molecular biomarker for endotoxicity. (+info)
Involvement of linear plasmids in aerobic biodegradation of vinyl chloride.
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Pseudomonas putida strain AJ and Ochrobactrum strain TD were isolated from hazardous waste sites based on their ability to use vinyl chloride (VC) as the sole source of carbon and energy under aerobic conditions. Strains AJ and TD also use ethene and ethylene oxide as growth substrates. Strain AJ contained a linear megaplasmid (approximately 260 kb) when grown on VC or ethene, but it contained no circular plasmids. While strain AJ was growing on ethylene oxide, it was observed to contain a 100-kb linear plasmid, and its ability to use VC as a substrate was retained. The linear plasmids in strain AJ were cured, and the ability of strain AJ to consume VC, ethene, and ethylene oxide was lost following growth on a rich substrate (Luria-Bertani broth) through at least three transfers. Strain TD contained three linear plasmids, ranging in size from approximately 90 kb to 320 kb, when growing on VC or ethene. As with strain AJ, the linear plasmids in strain TD were cured following growth on Luria-Bertani broth and its ability to consume VC and ethene was lost. Further analysis of these linear plasmids may help reveal the pathway for VC biodegradation in strains AJ and TD and explain why this process occurs at many but not all sites where groundwater is contaminated with chloroethenes. Metabolism of VC and ethene by strains AJ and TD is initiated by an alkene monooxygenase. Their yields during growth on VC (0.15 to 0.20 mg of total suspended solids per mg of VC) are similar to the yields reported for other isolates (i.e., Mycobacterium sp., Nocardioides sp., and Pseudomonas sp.). (+info)
Nodulation of Lupinus albus by strains of Ochrobactrum lupini sp. nov.
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The nodulation of legumes has for more than a century been considered an exclusive capacity of a group of microorganisms commonly known as rhizobia and belonging to the alpha-Proteobacteria. However, in the last 3 years four nonrhizobial species, belonging to alpha and beta subclasses of the Proteobacteria, have been described as legume-nodulating bacteria. In the present study, two fast-growing strains, LUP21 and LUP23, were isolated from nodules of Lupinus honoratus. The phylogenetic analysis based on the 16S and 23S rRNA gene sequences showed that the isolates belong to the genus Ochrobactrum. The strains were able to reinfect Lupinus plants. A plasmid profile analysis showed the presence of three plasmids. The nodD and nifH genes were located on these plasmids, and their sequences were obtained. These sequences showed a close resemblance to the nodD and nifH genes of rhizobial species, suggesting that the nodD and nifH genes carried by strain LUP21T were acquired by horizontal gene transfer. A polyphasic study including phenotypic, chemotaxonomic, and molecular features of the strains isolated in this study showed that they belong to a new species of the genus Ochrobactrum for which we propose the name Ochrobactrum lupini sp. nov. Strain LUP21T (LMG 20667T) is the type strain. (+info)
Genotyping of Ochrobactrum spp. by AFLP analysis.
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AFLP was used to analyze the genetic diversity among Ochrobactrum strains. AFLP patterns showed a great genomic variability that separated the samples into three distinct clusters. Ochrobactrum intermedium was found to be closely related to Brucella abortus S99. (+info)
Molecular and phenotypic features for identification of the opportunistic pathogens Ochrobactrum spp.
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Among the six species characterized within the genus Ochrobactrum, Ochrobactrum anthropi and Ochrobactrum intermedium are currently reported as opportunistic pathogens in humans. Since the species identification is mainly based on 16S rDNA analysis, the aim of this study was to search for other characteristics useful for Ochrobactrum species discrimination. Ribotyping, morphological and biochemical analyses, and antimicrobial susceptibility testing were performed for a panel of 35 clinical isolates, first identified to the species level using 16S rDNA sequencing. Type and reference strains of five Ochrobactrum species were comparatively analysed. Commercial identification systems such as API 20NE and VITEK 2 were tested for their ability to identify Ochrobactrum anthropi and to detect other members of the genus Ochrobactrum. An improved protocol for the identification of Ochrobactrum spp. by routine medical microbiology practices is proposed: isolation of a non-fastidious non-fermenting oxidase-positive Gram-negative rod resistant to all beta-lactams except imipenem indicates the genus Ochrobactrum, and the API 20NE system confirms the genus identification for most strains, whereas the VITEK 2 system using ID-GNB cards was less powerful. Urease activity, the mucoidy of the colonies, growth at 45 degrees C on tryptic soy agar, and susceptibility to colistin, tobramycin and netilmicin should be considered as differential characteristics for identification of O. anthropi and O. intermedium to the species level. However, definitive identification depends on genotyping methods. (+info)
Involvement of coenzyme M during aerobic biodegradation of vinyl chloride and ethene by Pseudomonas putida strain AJ and Ochrobactrum sp. strain TD.
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The involvement of coenzyme M in aerobic biodegradation of vinyl chloride and ethene in Pseudomonas putida strain AJ and Ochrobactrum sp. strain TD was demonstrated using PCR, hybridization, and enzyme assays. The results of this study extend the range of eubacteria known to use epoxyalkane:coenzyme M transferase. (+info)
Ochrobactrum oryzae sp. nov., an endophytic bacterial species isolated from deep-water rice in India.
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A non-pigmented, motile, Gram-negative bacterium designated MTCC 4195(T) was isolated from surface-sterilized seeds and plant tissue from deep-water rice (Oryza sativa) cultivated in Suraha Tal Lake in northern India. This isolate was shown to reinfect and colonize deep-water rice endophytically. The highest level of 16S rRNA sequence similarity (96.8 %) to strain MTCC 4195(T) was shown by Ochrobactrum gallinifaecis DSM 15295(T). Strain MTCC 4195(T) utilized gamma-hydroxybutyric acid, adonitol, d-glucosaminic acid and arabinose as carbon sources, but failed to use gentiobiose or citrate. The cell-wall fatty acids of strain MTCC 4195(T) were characterized by the presence of a relatively large proportion of C(18 : 1)omega7c and a relative small proportion of C(16 : 0) in comparison with Ochrobactrum species. DNA-DNA relatedness studies showed less than 52 % binding with the DNAs of type strains of other species of the genus Ochrobactrum. On the basis of phenotypic and genotypic characteristics and the results of 16S rRNA gene sequence analysis, the novel species Ochrobactrum oryzae sp. nov. is proposed, with MTCC 4195(T) (=DSM 17471(T)) as the type strain. (+info)