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Sample records for rhizobium bacteroid development

  1. Carbon Metabolism Enzymes of Rhizobium tropici Cultures and Bacteroids.

    PubMed

    Romanov, V I; Hernández-Lucas, I; Martínez-Romero, E

    1994-07-01

    We determined the activities of selected enzymes involved in carbon metabolism in free-living cells of Rhizobium tropici CFN299 grown in minimal medium with different carbon sources and in bacteroids of the same strain. The set of enzymatic activities in sucrose-grown cells suggests that the pentose phosphate pathway, with the participation of the Entner-Doudoroff pathway, is probably the primary route for sugar catabolism. In glutamate- and malate-grown cells, high activities of the gluconeogenic enzymes (phosphoenolpyruvate carboxykinase, fructose-6-phosphate aldolase, and fructose bisphosphatase) were detected. In bacteroids, isolated in Percoll gradients, the levels of activity for many of the enzymes measured were similar to those of malate-grown cells, except that higher activities of glucokinase, glucose-6-phosphate dehydrogenase, and NAD-dependent phosphogluconate dehydrogenase were detected. Phosphoglucomutase and UDP glucose pyrophosphorylase showed high and constant levels under all growth conditions and in bacteroids. PMID:16349319

  2. Fluorescence studies with malate dehydrogenase from rhizobium japonicum 3I1B-143 bacteroids: a two-tryptophan containing protein

    NASA Astrophysics Data System (ADS)

    Ghiron, Camillo A.; Eftink, Maurice R.; Waters, James K.; Emerich, David W.

    1990-05-01

    A number of fluorescence studies, both of trp residues and bound NADH, have been reported for porcine MDH. The large number of trp residues (6) complicates the interpretation of some studies. To circumvent this we have performed studies with a two tryptophan (per subunit) MDH from Rhizobium japonicum 311B-143 bacteroids. We have performed phase/modulation fluorescence lifetime measurements, as a function of temperature and added quencher KI, in order to resolved the 1.3 ns (blue) and 6.6 ns (red) contributions from the two classes of trp residues. Anisotropy decay studies have also been performed. The binding of NADH dynamically quenches the fluorescence of both tip residues, but, unlike mammalian cytoplasmic and mitochondrial MDH, there is not a large enhancement in fluorescence of bound NADH upon forming a ternary complex with either tartronic acid or D-malonate.

  3. Membrane energization in relation with nitrogen fixation in Azotobacter vinelandii and Rhizobium leguminosarum bacteroids.

    PubMed

    Veeger, C; Laane, C; Scherings, G; van Zeeland Wolbers, L

    1978-01-01

    Nitrogen fixation in A. vinelandii and R. leguminosarum bacteroides shows identical characteristics with respect to the dependence on membrane energization, the sensitivity to uncouplers, the ATP/ADP-ratio, and the dependences on flavodoxinhydroquinone as electrondonor. Although we have been successful in preparing inside-out vesicles which can be energized, attempts to couple these membranes to N2-ase were still unsuccessful. One of the major problems could be the failure to energize these vesicles directly by ATP. Although subject to polymerisation after addition of MgCl2, it could be shown that the actual mol.wt. of the O2-stable N2-ase complex is about 300,000 in agreement with a 1:1:1 stoichiometry of the three constituent proteins, namely, component I, component II and the 2Fe-2S protein. PMID:667180

  4. Terminal bacteroid differentiation in the legume-rhizobium symbiosis: nodule-specific cysteine-rich peptides and beyond.

    PubMed

    Alunni, Benoît; Gourion, Benjamin

    2016-07-01

    Contents 411 I. 411 II. 412 III. 412 IV. 413 V. 414 VI. 414 VII. 415 VIII. 415 416 References 416 SUMMARY: Terminal bacteroid differentiation (TBD) is a remarkable case of bacterial cell differentiation that occurs after rhizobia are released intracellularly within plant cells of symbiotic legume organs called nodules. The hallmarks of TBD are cell enlargement, genome amplification and membrane permeabilization. This plant-driven process is governed by a large family of bacteroid-targeted nodule-specific cysteine-rich (NCR) peptides that were until recently thought to be restricted to a specific lineage of the legume family, including the model plant Medicago truncatula. Recently, new plant and bacterial factors involved in TBD have been identified, challenging our view of this phenomenon at mechanistic and evolutionary levels. Here, we review the recent literature and discuss emerging questions about the mechanisms and the role(s) of TBD. PMID:27241115

  5. Development of new host-specific Bacteroides qPCRs for the identification of fecal contamination sources in water.

    PubMed

    Gómez-Doñate, Marta; Casanovas-Massana, Arnau; Muniesa, Maite; Blanch, Anicet R

    2016-02-01

    Bacteroides spp. have been proposed as indicators of fecal contamination in microbial source tracking (MST) methodologies. The aim of this study was to develop new qPCR assays that target host-specific Bacteroidal 16S ribosomal RNA genes, to determine the source of fecal contamination in water. Denaturing gradient gel electrophoresis (DGGE) was used to select for host-specific bands of Bacteroides associated with a fecal pollution source and later to design four qPCR host-specific assays. A set of common primers for Bacteroides spp., four different Bacteroides spp. host-associated hydrolysis probes (human, cattle, pig, and poultry), and one hydrolysis probe for the Bacteroides genus were designed. This set of qPCR assays together with other previously developed Bacteroidetes MST targets were used to analyze water samples with fecal contamination from the four sources studied. The host-specific Bacteroides qPCRs designed for human (HMprobeBac), pig (PGprobeBac), and poultry (PLprobeBac) were highly specific for its sources (1.0, 0.97, and 1.0, respectively) although its sensitivity was lower (0.45, 0.50, and 0.73, respectively). The cattle-specific qPCR was totally unspecific and was discarded for future experiments. When compared to previously designed assays, the human and pig qPCRs showed better accuracies (0.86 and 0.84) than their counterparts HF183 and Pig-2-Bac (0.38 and 0.65). Thus, the newly designed human, pig, and poultry qPCR assays outperform other methods developed until date and may be useful for source tracking purposes. PMID:26763626

  6. Microgravity effects on the legume/Rhizobium symbiosis

    NASA Astrophysics Data System (ADS)

    Urban, James E.

    1997-01-01

    Symbiotic nitrogen fixation is of critical importance to world agriculture and likely will be a critical part of life support systems developed for prolonged missions in space. Bacteroid formation, an essential step in an effective Dutch White Clover/Rhizobium leguminosarum bv trifolii symbiosis, is induced by succinic acid which is produced by the plant and which is bound and incorporated by the bacterium. Aspirin mimics succinate in its role as a bacteroid inducer and measures of aspirin binding mimiced measurements of succinate binding. In normal gravity (1×g), rhizobium bacteria immediately bound relatively high levels of aspirin (or succinate) in a readily reversible manner. Within a few seconds a portion of this initially bound aspirin became irreversibly bound. In the microgravity environment aboard the NASA 930 aircraft, rhizobia did not display the initial reversible binding of succinate, but did display a similar kinetic pattern of irreversible binding, and ultimately bound 32% more succinate (Acta Astronautica 36:129-133, 1995.) In normal gravity succinate treated cells stop dividing and swell to their maximum size (twice the normal cell volume) within a time equivalent to the time required for two normal cell doublings. Swelling in microgravity was tested in FPA and BPM sample holders aboard the space shuttle (USML-1, and STS-54, 57, and 60.) The behavior of cells in the two sample holders was similar, and swelling behavior of cells in microgravity was identical to behavior in normal gravity.

  7. [The defense and regulatory mechanisms during development of legume-Rhizobium symbiosis].

    PubMed

    Glian'ko, A K; Akimova, G P; Sokolova, M G; Makarova, L E; Vasil'eva, G G

    2007-01-01

    The roles of indolylacetic acid, the peroxidase system, catalase, active oxygen species, and phenolic compounds in the physiological and biochemical mechanisms involved in the autoregulation of nodulation in the developing legume-Rhizobium symbiosis were studied. It was inferred that the concentration of indolylacetic acid in the roots of inoculated plants, controlled by the enzymes of the peroxidase complex, is the signal permitting or limiting nodulation at the initial stages of symbiotic interaction. Presumably, the change in the level of active oxygen species is determined by an antioxidant activity of phenolic compounds. During the development of symbiosis, phytohormones, antioxidant enzymes, and active oxygen species may be involved in the regulation of infection via both a direct antibacterial action and regulation of functional activity of the host plant defense systems. PMID:17619575

  8. Rhizobium lipopolysaccharide modulates infection thread development in white clover root hairs.

    PubMed Central

    Dazzo, F B; Truchet, G L; Hollingsworth, R I; Hrabak, E M; Pankratz, H S; Philip-Hollingsworth, S; Salzwedel, J L; Chapman, K; Appenzeller, L; Squartini, A

    1991-01-01

    The interaction between Rhizobium lipopolysaccharide (LPS) and white clover roots was examined. The Limulus lysate assay indicated that Rhizobium leguminosarum bv. trifolii (hereafter called R. trifolii) released LPS into the external root environment of slide cultures. Immunofluorescence and immunoelectron microscopy showed that purified LPS from R. trifolii 0403 bound rapidly to root hair tips and infiltrated across the root hair wall. Infection thread formation in root hairs was promoted by preinoculation treatment of roots with R. trifolii LPS at a low dose (up to 5 micrograms per plant) but inhibited at a higher dose. This biological activity of LPS was restricted to the region of the root present at the time of exposure to LPS, higher with LPS from cells in the early stationary phase than in the mid-exponential phase, incubation time dependent, incapable of reversing inhibition of infection by NO3- or NH4+, and conserved among serologically distinct LPSs from several wild-type R. trifolii strains (0403, 2S-2, and ANU843). In contrast, infections were not increased by preinoculation treatment of roots with LPSs from R. leguminosarum bv. viciae strain 300, R. meliloti 102F28, or members of the family Enterobacteriaceae. Most infection threads developed successfully in root hairs pretreated with R. trifolii LPS, whereas many infections aborted near their origins and accumulated brown deposits if pretreated with LPS from R. meliloti 102F28. LPS from R. leguminosarum 300 also caused most infection threads to abort. Other specific responses of root hairs to infection-stimulating LPS from R. trifolii included acceleration of cytoplasmic streaming and production of novel proteins. Combined gas chromatography-mass spectroscopy and proton nuclear magnetic resonance analyses indicated that biologically active LPS from R. trifolii 0403 in the early stationary phase had less fucose but more 2-O-methylfucose, quinovosamine, 3,6-dideoxy-3-(methylamino)galactose, and

  9. Rhizobium meliloti mutants unable to synthesize anthranilate display a novel symbiotic phenotype.

    PubMed Central

    Barsomian, G D; Urzainqui, A; Lohman, K; Walker, G C

    1992-01-01

    Analyses of Rhizobium meliloti trp auxotrophs suggest that anthranilate biosynthesis by the R. meliloti trpE(G) gene product is necessary during nodule development for establishment of an effective symbiosis. trpE(G) mutants, as well as mutants blocked earlier along this pathway in aromatic amino acid biosynthesis, form nodules on alfalfa that have novel defects. In contrast, R. meliloti trp mutants blocked later in the tryptophan-biosynthetic pathway form normal, pink, nitrogen-fixing nodules. trpE(G) mutants form two types of elongated, defective nodules containing unusually extended invasion zones on alfalfa. One type contains bacteroids in its base and is capable of nitrogen fixation, while the other lacks bacteroids and cannot fix nitrogen. The trpE(G) gene is expressed in normal nodules. Models are discussed to account for these observations, including one in which anthranilate is postulated to act as an in planta siderophore. Images PMID:1320610

  10. Alfalfa Enod12 genes are differentially regulated during nodule development by Nod factors and Rhizobium invasion.

    PubMed Central

    Bauer, P; Crespi, M D; Szécsi, J; Allison, L A; Schultze, M; Ratet, P; Kondorosi, E; Kondorosi, A

    1994-01-01

    MsEnod12A and MsEnod12B are two early nodulin genes from alfalfa (Medicago sativa). Differential expression of these genes was demonstrated using a reverse transcription-polymerase chain reaction approach. MsEnod12A RNA was detected only in nodules and not in other plant tissues. In contrast, MsEnod12B transcripts were found in nodules and also at low levels in roots, flowers, stems, and leaves. MsEnod12B expression was enhanced in the root early after inoculation with the microsymbiont Rhizobium meliloti and after treatment with purified Nod factors, whereas MsEnod12A induction was detected only when developing nodules were visible. In situ hybridization showed that in nodules, MsEnod12 expression occurred in the infection zone. In empty Fix- nodules the MsEnod12A transcript level was much reduced, and in spontaneous nodules it was not detectable. These data indicate that MsEnod12B expression in roots is related to the action of Nod factors, whereas MsEnod12A expression is associated with the invasion process in nodules. Therefore, alfalfa possesses different mechanisms regulating MsEnod12A and MsEnod12B expression. PMID:8066132

  11. Characterization of the lipopolysaccharide from a Rhizobium phaseoli mutant that is defective in infection thread development.

    PubMed Central

    Carlson, R W; Kalembasa, S; Turowski, D; Pachori, P; Noel, K D

    1987-01-01

    The lipopolysaccharide (LPS) from a Rhizobium phaseoli mutant, CE109, was isolated and compared with that of its wild-type parent, CE3. A previous report has shown that the mutant is defective in infection thread development, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that it has an altered LPS (K. D. Noel, K. A. VandenBosch, and B. Kulpaca, J. Bacteriol. 168:1392-1462, 1986). Mild acid hydrolysis of the CE3 LPS released a polysaccharide and an oligosaccharide, PS1 and PS2, respectively. Mild acid hydrolysis of CE109 LPS released only an oligosaccharide. Chemical and immunochemical analyses showed that CE3-PS1 is the antigenic O chain of this strain and that CE109 LPS does not contain any of the major sugar components of CE3-PS1. CE109 oligosaccharide was identical in composition to CE3-PS2. The lipid A's from both strains were very similar in composition, with only minor quantitative variations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of CE3 and CE109 LPSs showed that CE3 LPS separated into two bands, LPS I and LPS II, while CE109 had two bands which migrated to positions similar to that of LPS II. Immunoblotting with anti-CE3 antiserum showed that LPS I contains the antigenic O chain of CE3, PS1. Anti-CE109 antiserum interacted strongly with both CE109 LPS bands and CE3 LPS II and interacted weakly with CE3 LPS I. Mild-acid hydrolysis of CE3 LPS I, extracted from the polyacrylamide gel, showed that it contained both PS1 and PS2. The results in this report showed that CE109 LPS consists of only the lipid A core and is missing the antigenic O chain. Images PMID:3667520

  12. Evaluation of nitrate reductase activity in Rhizobium japonicum

    SciTech Connect

    Streeter, J.G.; DeVine, P.J.

    1983-08-01

    Nitrate reductase activity was evaluated by four approaches, using four strains of Rhizobium japonicum and 11 chlorate-resistant mutants of the four strains. It was concluded that in vitro assays with bacteria or bacteroids provide the most simple and reliable assessment of the presence or absence of nitrate reductase. Nitrite reductase activity with methyl viologen and dithionite was found, but the enzyme activity does not confound the assay of nitrate reductase. 18 references

  13. A Peptidoglycan-Remodeling Enzyme Is Critical for Bacteroid Differentiation in Bradyrhizobium spp. During Legume Symbiosis.

    PubMed

    Gully, Djamel; Gargani, Daniel; Bonaldi, Katia; Grangeteau, Cédric; Chaintreuil, Clémence; Fardoux, Joël; Nguyen, Phuong; Marchetti, Roberta; Nouwen, Nico; Molinaro, Antonio; Mergaert, Peter; Giraud, Eric

    2016-06-01

    In response to the presence of compatible rhizobium bacteria, legumes form symbiotic organs called nodules on their roots. These nodules house nitrogen-fixing bacteroids that are a differentiated form of the rhizobium bacteria. In some legumes, the bacteroid differentiation comprises a dramatic cell enlargement, polyploidization, and other morphological changes. Here, we demonstrate that a peptidoglycan-modifying enzyme in Bradyrhizobium strains, a DD-carboxypeptidase that contains a peptidoglycan-binding SPOR domain, is essential for normal bacteroid differentiation in Aeschynomene species. The corresponding mutants formed bacteroids that are malformed and hypertrophied. However, in soybean, a plant that does not induce morphological differentiation of its symbiont, the mutation does not affect the bacteroids. Remarkably, the mutation also leads to necrosis in a large fraction of the Aeschynomene nodules, indicating that a normally formed peptidoglycan layer is essential for avoiding the induction of plant immune responses by the invading bacteria. In addition to exopolysaccharides, capsular polysaccharides, and lipopolysaccharides, whose role during symbiosis is well defined, our work demonstrates an essential role in symbiosis for yet another rhizobial envelope component, the peptidoglycan layer. PMID:26959836

  14. Isolation of Bacteroides from fish and human fecal samples for identification of unique molecular markers.

    PubMed

    Kabiri, Leila; Alum, Absar; Rock, Channah; McLain, Jean E; Abbaszadegan, Morteza

    2013-12-01

    Bacteroides molecular markers have been used to identify human fecal contamination in natural waters, but recent work in our laboratory confirmed cross-amplification of several human-specific Bacteroides spp. assays with fecal DNA from fish. For identification of unique molecular markers, Bacteroides from human (n = 4) and fish (n = 7) fecal samples were cultured and their identities were further confirmed using Rapid ID 32A API strips. The 16S rDNA from multiple isolates from each sample was PCR amplified, cloned, and sequenced to identify unique markers for development of more stringent human-specific assays. In human feces, Bacteroides vulgatus was the dominant species (75% of isolates), whereas in tilapia feces, Bacteroides eggerthii was dominant (66%). Bacteroides from grass carp, channel catfish, and blue catfish may include Bacteroides uniformis, Bacteroides ovatus, or Bacteroides stercoris. Phylogenic analyses of the 16S rRNA gene sequences showed distinct Bacteroides groupings from each fish species, while human sequences clustered with known B. vulgatus. None of the fish isolates showed significant similarity to Bacteroides sequences currently deposited in NCBI (National Center for Biotechnology Information). This study expands the current sequence database of cultured fish Bacteroides. Such data are essential for identification of unique molecular markers in human Bacteroides that can be utilized in differentiating fish and human fecal contamination in water samples. PMID:24313449

  15. Development of a Gene Inactivation System for Bacteroides forsythus: Construction and Characterization of a BspA Mutant

    PubMed Central

    Honma, Kiyonobu; Kuramitsu, Howard K.; Genco, Robert J.; Sharma, Ashu

    2001-01-01

    Bacteroides forsythus is a gram-negative anaerobic bacterium associated with periodontitis. The bspA gene encoding a cell surface associated leucine-rich repeat protein (BspA) involved in adhesion to fibronectin and fibrinogen was recently cloned from this bacterium in our laboratory. We now describe the construction of a BspA-defective mutant of B. forsythus. This is the first report describing the generation of a specific gene knockout mutant of B. forsythus, and this procedure should be useful in establishing the identity of virulence-associated factors in these organisms. PMID:11402017

  16. Comparison of nucleic acid content in populations of free-living and symbiotic Rhizobium meliloti by flow microfluorometry.

    PubMed Central

    Paau, A S; Lee, D; Cowles, J R

    1977-01-01

    Populations of symbiotic Rhizobium meliloti extracted from alfalfa nodules were shown by flow microfluorometry to contain a significant number of bacteroids with higher nucleic acid content than the free-living rhizobia. Bacteroids with lower nucleic acid content than the free-living bacteria were not detected in significant quantities in these populations. These results indicate that the incapability of bacteroids to reestablish growth in nutrient media may not be caused by a decrease in nucleic acid content of the symbiotic rhizobia. PMID:838682

  17. Effects of microgravity on the binding of acetylsalicylic acid by Rhizobium leguminosarum bv. trifolii

    NASA Astrophysics Data System (ADS)

    Urban, James E.; Gerren, Richard; Zoelle, Jeffery

    1995-07-01

    Bacteroids can be induced in vitro by treating growing Rhizobium leguminosarum bv. trifolii with succinic acid or succinic acid structural analogs like acetylsalicylic acid. Quantitating bacteroid induction by measuring acetylsalicylic binding under normal (1 g) conditions showed two forms of binding to occur. In one form of binding cells immediately bound comparatively high levels of acetylsalicylic acid, but the binding was quickly reversed. The second form of binding increased with time by first-order kinetics, and reached saturation in 40 s. Similar experiments performed in the microgravity environment aboard the NASA 930 aircraft showed only one form of binding and total acetylsalicylic acid bound was 32% higher than at 1 g.

  18. (A structural assessment of the role of the cell surface carbohydrates of Rhizobium in the Rhizobium/legume symbiosis)

    SciTech Connect

    Hollingsworth, R.I.

    1991-01-01

    Research continued on the study of cell surface carbohydrates of Rhizobium. Objectives include: To characterize, at a structural level, the differences between the lipopolysaccharides of a representative number of strains from different Rhizobium species to determine which features of LPS structure are species-specific and might, therefore, be determinants of host specificity. Determine the effect(s) of nod gene induction on the structure of Rhizobium lipopolysaccharides and determine whether synthesis of a modified LPS molecule or a new surface glycoconjugate is initiated by nod gene induction. Develop a non-chemical means for rapidly screening large numbers of bacterial strains in order to determine which glycoconjugate structural features are conserved between strains of the same species. Provide the necessary structural information which, when coupled with developments in the rapidly expanding field of Rhizobium genetics, should lead to a clear understanding of the role of Rhizobium surface glycoconjugates in host/symbiont interactions. Progress is discussed.

  19. A rhizobium leguminosarum mutant defective in symbiotic iron acquisition

    SciTech Connect

    Nadler, K.D.; Chen, Jing-Wen; John, T.R. ); Johnston, A.W.B. )

    1990-02-01

    Iron acquisition by symbiotic Rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. Rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. The pop-1 mutation in strain 116 imparted to it a complex phenotype, characteristic of iron deficiency. Several iron(III)-solubilizing agents, such as citrate, hydroxyquinoline, and dihydroxybenzoate, stimulated growth of 116 on low-iron solid medium; anthranilic acid, the R. leguminosarum siderophore, inhibited low-iron growth of 116. The initial rate of {sup 55}Fe uptake by suspensions of iron-starved 116 cells was 10-fold less than that of iron-starved wild-type cells. Electron microscopic observations revealed no morphological abnormalities in the small, white nodules induced by 116. Nodule cortical cells were filled with vesicles containing apparently normal bacteroids. No premature degeneration of bacteroids or of plant cell organelles was evident. The authors mapped pop-1 by R plasmid-mediated conjugation and recombination to the ade-27-rib-2 region of the R. leguminosarum chromosome. No segregation of pop-1 and the symbiotic defect was observed among the recombinants from these crosses. Cosmid pKN1, a pLAFR1 derivative containing a 24-kilobase-pair fragment of R. leguminosarum DNA, conferred on 116 the ability to grow on dipyridyl medium and to fix nitrogen symbiotically.

  20. CERBERUS, a novel U-box protein containing WD-40 repeats, is required for formation of the infection thread and nodule development in the legume-Rhizobium symbiosis.

    PubMed

    Yano, Koji; Shibata, Satoshi; Chen, Wen-Li; Sato, Shusei; Kaneko, Takakazu; Jurkiewicz, Anna; Sandal, Niels; Banba, Mari; Imaizumi-Anraku, Haruko; Kojima, Tomoko; Ohtomo, Ryo; Szczyglowski, Krzysztof; Stougaard, Jens; Tabata, Satoshi; Hayashi, Makoto; Kouchi, Hiroshi; Umehara, Yosuke

    2009-10-01

    Endosymbiotic infection of legume plants by Rhizobium bacteria is initiated through infection threads (ITs) which are initiated within and penetrate from root hairs and deliver the endosymbionts into nodule cells. Despite recent progress in understanding the mutual recognition and early symbiotic signaling cascades in host legumes, the molecular mechanisms underlying bacterial infection processes and successive nodule organogenesis are still poorly understood. We isolated a novel symbiotic mutant of Lotus japonicus, cerberus, which shows defects in IT formation and nodule organogenesis. Map-based cloning of the causal gene allowed us to identify the CERBERUS gene, which encodes a novel protein containing a U-box domain and WD-40 repeats. CERBERUS expression was detected in the roots and nodules, and was enhanced after inoculation of Mesorhizobium loti. Strong expression was detected in developing nodule primordia and the infected zone of mature nodules. In cerberus mutants, Rhizobium colonized curled root hair tips, but hardly penetrated into root hair cells. The occasional ITs that were formed inside the root hair cells were mostly arrested within the epidermal cell layer. Nodule organogenesis was aborted prematurely, resulting in the formation of a large number of small bumps which contained no endosymbiotic bacteria. These phenotypic and genetic analyses, together with comparisons with other legume mutants with defects in IT formation, indicate that CERBERUS plays a critical role in the very early steps of IT formation as well as in growth and differentiation of nodules. PMID:19508425

  1. Characterization of bacteroides melaninogenicus.

    PubMed Central

    Harding, G K; Sutter, V L; Finegold, S M; Bricknell, K S

    1976-01-01

    Fifty-eight human isolates of Bacteroides melaninogenicus, 42 from a variety of clinical infections and the rest from normal flora, were studied for pigment production and ultraviolet light fluorescence and by forty biochemical and other tests, including end-product analysis by gas-liquid chromatography. In a number of instances, tests were repeated several times and the results were reproducible. Agar plate dilution susceptibility tests were also performed to 12 antimicrobial agents. These 58 strains could be reliably placed into three groups, corresponding to the three subspecies described, based on seven characteristics. These included acid production in peptone-yeast-glucose medium, production of n-butyric acid from peptone-yeast-glucose medium, esculin hydrolysis, starch hydrolysis, indole production, effect on milk, and lipase production. Production of hydrogen gas in peptone-yeast-fructose medium may be another distinguishing characteristic. In general there was not much difference in the susceptibility of the three groups to the various antimicrobial agents tested. Two strains had a minimal inhibitory concentration of penicillin G of 16 and 32 U/ml, respectively. Three strains did not produce a black pigment in spite of prolonged incubation on blood-containing media. PMID:10317

  2. Modulation of development, growth dynamics, wall crystallinity, and infection sites in white clover root hairs by membrane chitolipooligosaccharides from Rhizobium leguminosarum biovar trifolii.

    PubMed Central

    Dazzo, F B; Orgambide, G G; Philip-Hollingsworth, S; Hollingsworth, R I; Ninke, K O; Salzwedel, J L

    1996-01-01

    We used bright-field, time-lapse video, cross-polarized, phase-contrast, and fluorescence microscopies to examine the influence of isolated chitolipooligosaccharides (CLOSs) from wild-type Rhizobium leguminosarum bv. trifolii on development of white clover root hairs, and the role of these bioactive glycolipids in primary host infection. CLOS action caused a threefold increase in the differentiation of root epidermal cells into root hairs. At maturity, root hairs were significantly longer because of an extended period of active elongation without a change in the elongation rate itself. Time-series image analysis showed that the morphological basis of CLOS-induced root hair deformation is a redirection of tip growth displaced from the medial axis as previously predicted. Further studies showed several newly described infection-related root hair responses to CLOSs, including the localized disruption of the normal crystallinity in cell wall architecture and the induction of new infection sites. The application of CLOS also enabled a NodC- mutant of R. leguminosarum bv. trifolii to progress further in the infection process by inducing bright refractile spot modifications of the deformed root hair walls. However, CLOSs did not rescue the ability of the NodC- mutant to induce marked curlings or infection threads within root hairs. These results indicate that CLOS Nod factors elicit several host responses that modulate the growth dynamics and symbiont infectibility of white clover root hairs but that CLOSs alone are not sufficient to permit successful entry of the bacteria into root hairs during primary host infection in the Rhizobium-clover symbiosis. PMID:8655563

  3. Fecal detection of enterotoxigenic Bacteroides fragilis.

    PubMed

    Chen, L A; Van Meerbeke, S; Albesiano, E; Goodwin, A; Wu, S; Yu, H; Carroll, K; Sears, C

    2015-09-01

    Bacteroides fragilis is a common colonic symbiote of which one subtype, enterotoxigenic Bacteroides fragilis (ETBF), causes inflammatory diarrhea. However, asymptomatic ETBF colonization is common. Through its primary virulence factor, B. fragilis toxin (BFT), ETBF causes asymptomatic, chronic colitis in C57BL/6 mice and increased colon tumorigenesis in multiple intestinal neoplasia mice. Human studies suggest an association between ETBF infection, inflammatory bowel disease, and colon cancer. Additional studies on ETBF epidemiology are, therefore, crucial. The goal of this study is to develop a reliable fecal diagnostic for ETBF. To develop a sensitive assay for ETBF, we tested multiple protocols on mouse stools spiked with serially diluted ETBF. Each assay was based on either touchdown or quantitative polymerase chain reaction (qPCR) and used primers targeted to bft to detect ETBF. Using touchdown PCR or qPCR, the mean ETBF detection limit was 1.55 × 10(6) colony-forming units (CFU)/g stool and 1.33 × 10(4) CFU/g stool, respectively. Augmentation of Bacteroides spp. growth in fecal samples using PYGB (Peptone Yeast Glucose with Bile) broth enhanced ETBF detection to 2.93 × 10(2) CFU/g stool using the touchdown PCR method and 2.63 × 10(2) CFU/g stool using the qPCR method. Fecal testing using combined culture-based amplification and bft touchdown PCR is a sensitive assay for the detection of ETBF colonization and should be useful in studying the role of ETBF colonization in intestinal diseases, such as inflammatory bowel disease and colon cancer. We conclude that touchdown PCR with culture-based amplification may be the optimal ETBF detection strategy, as it performs as well as qPCR with culture-based amplification, but is a less expensive technique. PMID:26173688

  4. [A structural assessment of the role of the cell surface carbohydrates of Rhizobium in the Rhizobium/legume symbiosis]. Progress report, June 1989--June 1991

    SciTech Connect

    Hollingsworth, R.I.

    1991-12-31

    Research continued on the study of cell surface carbohydrates of Rhizobium. Objectives include: To characterize, at a structural level, the differences between the lipopolysaccharides of a representative number of strains from different Rhizobium species to determine which features of LPS structure are species-specific and might, therefore, be determinants of host specificity. Determine the effect(s) of nod gene induction on the structure of Rhizobium lipopolysaccharides and determine whether synthesis of a modified LPS molecule or a new surface glycoconjugate is initiated by nod gene induction. Develop a non-chemical means for rapidly screening large numbers of bacterial strains in order to determine which glycoconjugate structural features are conserved between strains of the same species. Provide the necessary structural information which, when coupled with developments in the rapidly expanding field of Rhizobium genetics, should lead to a clear understanding of the role of Rhizobium surface glycoconjugates in host/symbiont interactions. Progress is discussed.

  5. Products of Dark CO2 Fixation in Pea Root Nodules Support Bacteroid Metabolism 1

    PubMed Central

    Rosendahl, Lis; Vance, Carroll P.; Pedersen, Walther B.

    1990-01-01

    Products of the nodule cytosol in vivo dark [14C]CO2 fixation were detected in the plant cytosol as well as in the bacteroids of pea (Pisum sativum L. cv “Bodil”) nodules. The distribution of the metabolites of the dark CO2 fixation products was compared in effective (fix+) nodules infected by a wild-type Rhizobium leguminosarum (MNF 300), and ineffective (fix−) nodules of the R. leguminosarum mutant MNF 3080. The latter has a defect in the dicarboxylic acid transport system of the bacterial membrane. The 14C incorporation from [14C]CO2 was about threefold greater in the wild-type nodules than in the mutant nodules. Similarly, in wild-type nodules the in vitro phosphoenolpyruvate carboxylase activity was substantially greater than that of the mutant. Almost 90% of the 14C label in the cytosol was found in organic acids in both symbioses. Malate comprised about half of the total cytosol organic acid content on a molar basis, and more than 70% of the cytosol radioactivity in the organic acid fraction was detected in malate in both symbioses. Most of the remaining 14C was contained in the amino acid fraction of the cytosol in both symbioses. More than 70% of the 14C label found in the amino acids of the cytosol was incorporated in aspartate, which on a molar basis comprised only about 1% of the total amino acid pool in the cytosol. The extensive 14C labeling of malate and aspartate from nodule dark [14C]CO2 fixation is consistent with the role of phosphoenolpyruvate carboxlase in nodule dark CO2 fixation. Bacteroids from the effective wild-type symbiosis accumulated sevenfold more 14C than did the dicarboxylic acid transport defective bacteroids. The bacteroids of the effective MNF 300 symbiosis contained the largest proportion of the incorporated 14C in the organic acids, whereas ineffective MNF 3080 bacteroids mainly contained 14C in the amino acid fraction. In both symbioses a larger proportion of the bacteroid 14C label was detected in malate and aspartate

  6. Rhizobium sp. strain ORS571 ammonium assimilation and nitrogen fixation.

    PubMed Central

    Donald, R G; Ludwig, R A

    1984-01-01

    Among rhizobia studied, Rhizobium sp. strain ORS571 alone grew unambiguously on N2 as sole N source. In ORS571 , only the glutamine synthetase (GS)-glutamate synthase ( GOGAT ) pathway assimilated ammonium. However, ORS571 exhibited two unique physiological aspects of this pathway: ORS571 had only GS I, whereas all other Rhizobiaceae studied had both GS I and GS II, and both NADPH- and NADH-dependent GOGAT activities were present. ORS571 GS-affected and NADPH- GOGAT -affected mutant strains were defective in both ammonium assimilation (Asm-) and N2 fixation (Nif-) in culture and in planta ; NADH- GOGAT mutants were Asm- but Nif+. "Bacteroid" GS activity was essentially nil, suggesting symbiotic ammonium export. Physiological studies on effects of glutamine, ammonium, methionine sulfoximine, and diazo-oxo-norleucine on nitrogenase induction in culture implied a regulatory role for the intracellular glutamine pool. Images PMID:6144666

  7. Identification and manipulation of Rhizobium phytohormone genes

    SciTech Connect

    Ditta, G.S.

    1988-06-27

    The goal of this project was to determine whether phytohormone production by the gram-negative bacterium Rhizobium meliloti is required for successful modulation and symbiosis with alfalfa. specifically, we undertook the study of indoleacetic acid (IAA; auxin) production by R. meliloti and sought to create a mutant totally deficient in IAA biosynthesis. For many years it has been known that rhizobia are capable of synthesizing and excreting IAA, and it has often been suggested that this could be of importance for the initiation of root nodule development. Published work demonstrating the involvement of bacterial IAA genes in pathogenesis by Pseudomonas syringae and Agrobacterium tumefaciens further emphasized the need for this type of study in Rhizobium.

  8. Lipopolysaccharide O-Chain Core Region Required for Cellular Cohesion and Compaction of In Vitro and Root Biofilms Developed by Rhizobium leguminosarum

    PubMed Central

    Russo, Daniela M.; Abdian, Patricia L.; Posadas, Diana M.; Williams, Alan; Vozza, Nicolás; Giordano, Walter; Kannenberg, Elmar; Downie, J. Allan

    2014-01-01

    The formation of biofilms is an important survival strategy allowing rhizobia to live on soil particles and plant roots. Within the microcolonies of the biofilm developed by Rhizobium leguminosarum, rhizobial cells interact tightly through lateral and polar connections, forming organized and compact cell aggregates. These microcolonies are embedded in a biofilm matrix, whose main component is the acidic exopolysaccharide (EPS). Our work shows that the O-chain core region of the R. leguminosarum lipopolysaccharide (LPS) (which stretches out of the cell surface) strongly influences bacterial adhesive properties and cell-cell cohesion. Mutants defective in the O chain or O-chain core moiety developed premature microcolonies in which lateral bacterial contacts were greatly reduced. Furthermore, cell-cell interactions within the microcolonies of the LPS mutants were mediated mostly through their poles, resulting in a biofilm with an altered three-dimensional structure and increased thickness. In addition, on the root epidermis and on root hairs, O-antigen core-defective strains showed altered biofilm patterns with the typical microcolony compaction impaired. Taken together, these results indicate that the surface-exposed moiety of the LPS is crucial for proper cell-to-cell interactions and for the formation of robust biofilms on different surfaces. PMID:25416773

  9. MgtE From Rhizobium leguminosarum Is a Mg²⁺ Channel Essential for Growth at Low pH and N2 Fixation on Specific Plants.

    PubMed

    Hood, Graham; Karunakaran, Ramakrishnan; Downie, J Allan; Poole, Philip

    2015-12-01

    MgtE is predicted to be a Rhizobium leguminosarum channel and is essential for growth when both Mg²⁺ is limiting and the pH is low. N₂was only fixed at 8% of the rate of wild type when the crop legume Pisum sativum was inoculated with an mgtE mutant of R. leguminosarum and, although bacteroids were present, they were few in number and not fully developed. R. leguminosarum MgtE was also essential for N₂fixation on the native legume Vicia hirsuta but not when in symbiosis with Vicia faba. The importance of MgtE and the relevance of the contrasting phenotypes is discussed. PMID:26422403

  10. A carbonic anhydrase gene is induced in the nodule primordium and its cell-specific expression is controlled by the presence of Rhizobium during development.

    PubMed

    Coba de la Peña, T; Frugier, F; McKhann, H I; Bauer, P; Brown, S; Kondorosi, A; Crespi, M

    1997-03-01

    Under nitrogen starvation, Rhizobium meliloti is able to induce nitrogen-fixing nodules on alfalfa roots. Certain alfalfa cultivars spontaneously develop pseudonodules in the absence of bacteria. A transcript, Msca1, expressed in spontaneous and R. meliloti-induced nodules, that codes for a carbonic anhydrase (CA), an enzyme catalyzing the hydration of CO2 has been identified. This is the first CA gene cloned from a non-photosynthetic tissue in plants. Msca1 was activated initially in all cells of the bacterium-induced nodule primordium and was also induced by cytokinin treatment of alfalfa roots. The presence of CA enzymatic activity in different nodule types was demonstrated. Thus, Msca1 is a new early nodulin gene with a function possibly related to the increased amyloplast deposition of the dividing cortical cells. Msca1 transcripts were subsequently found mainly in a peripheral envelope of cells in developing and mature nodules. This novel pattern of gene expression is controlled by the presence of the bacterium inside the nodule. Sucrose synthase and phosphoenol pyruvate carboxylase (PEPC), other genes of the carbon fixation metabolism, were expressed in the same peripheral cells and even more strongly in the nitrogen-fixing region. Analysis of expression patterns of these genes indicated that early CA function may not be related to carbon fixation through PEPC. CA might be acting in pH regulation and/or CO2/HCO3-transport during nodule initiation. Thus, carbonic anhydrase may play different roles at several stages of nodule development and function. PMID:9107031

  11. Multiple antibiotic resistance in Rhizobium japonicum.

    PubMed

    Cole, M A; Elkan, G H

    1979-05-01

    A total of 48 strains of the soil bacterium Rhizobium japonicum were screened for their response to several widely used antibiotics. Over 60% of the strains were resistant to chloramphenicol, polymyxin B, and erythromycin, and 47% or more of the strains were resistant to neomycin and penicillin G, when tested by disk assay procedures. The most common grouping of resistances in strains was simultaneous resistance to tetracycline, penicillin G, neomycin, chloramphenicol, and streptomycin (25% of all strains tested). The occurrence of multiple drug resistance in a soil bacterium that is not a vertebrate pathogen suggests that chemotherapeutic use of antibiotics is not required for the development of multiple drug resistance. PMID:485137

  12. The development of plasmid-free strains of Agrobacterium tumefaciens by using incompatibility with a Rhizobium meliloti plasmid to eliminate pAtC58.

    PubMed

    Hynes, M F; Simon, R; Pühler, A

    1985-03-01

    Agrobacterium tumefaciens strains LBA275 and LBA290 were cured of their cryptic plasmid pAtC58 by the introduction of the Rhizobium meliloti plasmid pRme41a, which is incompatible with pAtC58. pRme41a and pTiC58, the resident Ti plasmid of LBA275, were subsequently eliminated by growth at supraoptimal temperature (40 degrees C). The resulting plasmid-free Agrobacterium strains, UBAPF1 and UBAPF2, have proved extremely useful for the study of Rhizobium plasmids. The loss of the cryptic plasmid pAtC58 has no effect on the tumor-forming ability of the Agrobacterium strains; when the Ti plasmid is present, normal tumors are formed on Kalanchoe daigremontiana. PMID:4001194

  13. Fine Structure of Bacteroids in Root Nodules of Vigna sinensis, Acacia longifolia, Viminaria juncea, and Lupinus angustifolius

    PubMed Central

    Dart, P. J.; Mercer, F. V.

    1966-01-01

    Dart, P. J. (University of Sydney, Sydney, Australia), and F. V. Mercer. Fine structure of bacteroids in root nodules of Vigna sinensis, Acacia longifolia, Viminaria juncea, and Lupinus angustifolius. J. Bacteriol. 91:1314–1319.—In nodules of Vigna sinensis, Acacia longifolia, and Viminaria juncea, membrane envelopes enclose groups of bacteroids. The bacteroids often contain inclusion granules and electron-dense bodies, expand little during development, and retain their rod form with a compact, central nucleoid area. The membrane envelope may persist around bacteroids after host cytoplasm breakdown. In nodules of Lupinus angustifolius, the membrane envelopes enclose only one or two bacteroids, which expand noticeably during development and change from their initial rod structure. Images PMID:5929757

  14. Characterization of Bacteroides forsythus isolates.

    PubMed

    Takemoto, T; Kurihara, H; Dahlen, G

    1997-06-01

    Fifteen Bacteroides forsythus strains freshly isolated from patients with periodontitis were used together with three collection strains and one type strain for characterization of growth on various media; determination of enzymatic profiles, antibiotic susceptibility profiles, 16S rRNA ribotypes, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) outer membrane protein profiles, and pathogenicity; and gas chromatography analysis by using a wound chamber model in rabbits. All strains were stimulated by N-acetylmuramic acid, while one strain needed a further supplement such as yeast extract for optimal growth. All strains showed trypsin-like activity. While 10 different ribotypes were found, the SDS-PAGE profiles revealed similar patterns for all strains. All strains were sensitive to penicillin G (MICs, <0.5 microg/ml), ampicillin (MICs, <1.0 microg/ml), amoxicillin (MICs, <0.38 microg/ml), metronidazole (MICs, <0.005 microg/ml), tetracycline (MICs, <0.19 microg/ml), doxycycline (MICs, 0.05 microg/ml), erythromycin (MICs, <0.4 microg/ml), and clindamycin (MICs, <0.016 microg/ml), while they were less sensitive to ciprofloxacin (MICs, <4 microg/ml). B. forsythus did not cause abscess formation by monoinoculation. B. forsythus coinoculated with Fusobacterium nucleatum ATCC 10953 caused abscess formation in 75% of rabbits, while it caused abscess formation in 100% of rabbits when it was coinoculated with Porphyromonas gingivalis FDC 381. In the case of the latter combination, four of six rabbits died of sepsis after 6 to 7 days, and P. gingivalis and B. forsythus were recovered from the heart blood at a proportion of 10:1. B. forsythus strains were highly virulent and invasive in combination with P. gingivalis. PMID:9163447

  15. Characterization of Bacteroides forsythus isolates.

    PubMed Central

    Takemoto, T; Kurihara, H; Dahlen, G

    1997-01-01

    Fifteen Bacteroides forsythus strains freshly isolated from patients with periodontitis were used together with three collection strains and one type strain for characterization of growth on various media; determination of enzymatic profiles, antibiotic susceptibility profiles, 16S rRNA ribotypes, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) outer membrane protein profiles, and pathogenicity; and gas chromatography analysis by using a wound chamber model in rabbits. All strains were stimulated by N-acetylmuramic acid, while one strain needed a further supplement such as yeast extract for optimal growth. All strains showed trypsin-like activity. While 10 different ribotypes were found, the SDS-PAGE profiles revealed similar patterns for all strains. All strains were sensitive to penicillin G (MICs, <0.5 microg/ml), ampicillin (MICs, <1.0 microg/ml), amoxicillin (MICs, <0.38 microg/ml), metronidazole (MICs, <0.005 microg/ml), tetracycline (MICs, <0.19 microg/ml), doxycycline (MICs, 0.05 microg/ml), erythromycin (MICs, <0.4 microg/ml), and clindamycin (MICs, <0.016 microg/ml), while they were less sensitive to ciprofloxacin (MICs, <4 microg/ml). B. forsythus did not cause abscess formation by monoinoculation. B. forsythus coinoculated with Fusobacterium nucleatum ATCC 10953 caused abscess formation in 75% of rabbits, while it caused abscess formation in 100% of rabbits when it was coinoculated with Porphyromonas gingivalis FDC 381. In the case of the latter combination, four of six rabbits died of sepsis after 6 to 7 days, and P. gingivalis and B. forsythus were recovered from the heart blood at a proportion of 10:1. B. forsythus strains were highly virulent and invasive in combination with P. gingivalis. PMID:9163447

  16. Modulation of endogenous indole-3-acetic acid biosynthesis in bacteroids within Medicago sativa nodules.

    PubMed

    Bianco, C; Senatore, B; Arbucci, S; Pieraccini, G; Defez, R

    2014-07-01

    To evaluate the dose-response effects of endogenous indole-3-acetic acid (IAA) on Medicago plant growth and dry weight production, we increased the synthesis of IAA in both free-living and symbiosis-stage rhizobial bacteroids during Rhizobium-legume symbiosis. For this purpose, site-directed mutagenesis was applied to modify an 85-bp promoter sequence, driving the expression of iaaM and tms2 genes for IAA biosynthesis. A positive correlation was found between the higher expression of IAA biosynthetic genes in free-living bacteria and the increased production of IAA under both free-living and symbiotic conditions. Plants nodulated by RD65 and RD66 strains, synthetizing the highest IAA concentration, showed a significant (up to 73%) increase in the shoot fresh weight and upregulation of nitrogenase gene, nifH, compared to plants nodulated by the wild-type strain. When these plants were analyzed by confocal microscopy, using an anti-IAA antibody, the strongest signal was observed in bacteroids of Medicago sativa RD66 (Ms-RD66) plants, even when they were located in the senescent nodule zone. We show here a simple system to modulate endogenous IAA biosynthesis in bacteria nodulating legumes suitable to investigate which is the maximum level of IAA biosynthesis, resulting in the maximal increase of plant growth. PMID:24814784

  17. The effect of environmental conditions on expression of Bacteroides fragilis and Bacteroides thetaiotaomicron C10 protease genes

    PubMed Central

    2012-01-01

    Background Bacteroides fragilis and Bacteroides thetaiotaomicron are members of the normal human intestinal microbiota. However, both organisms are capable of causing opportunistic infections, during which the environmental conditions to which the bacteria are exposed change dramatically. To further explore their potential for contributing to infection, we have characterized the expression in B. thetaiotaomicron of four homologues of the gene encoding the C10 cysteine protease SpeB, a potent extracellular virulence factor produced by Streptococcus pyogenes. Results We identified a paralogous set of genes (btp genes) in the B. thetaiotaomicron genome, that were related to C10 protease genes we recently identified in B. fragilis. Similar to C10 proteases found in B. fragilis, three of the B. thetaiotaomicron homologues were transcriptionally coupled to genes encoding small proteins that are similar in structural architecture to Staphostatins, protease inhibitors associated with Staphopains in Staphylococcus aureus. The expression of genes for these C10 proteases in both B. fragilis and B. thetaiotaomicron was found to be regulated by environmental stimuli, in particular by exposure to oxygen, which may be important for their contribution to the development of opportunistic infections. Conclusions Genes encoding C10 proteases are increasingly identified in operons which also contain genes encoding proteins homologous to protease inhibitors. The Bacteroides C10 protease gene expression levels are responsive to different environmental stimuli suggesting they may have distinct roles in the bacterial-host interaction. PMID:22943521

  18. SURVIVAL AND DETECTION OF 'BACTEROIDES' SPP., PROSPECTIVE INDICATOR BACTERIA

    EPA Science Inventory

    Preliminary experiments were performed to assess the use of intestinal Bacteroides spp. as indicators of fecal contamination of water. Viable counts of Bacteroides fragilis, an anaerobic bacterium, declined more rapidly than those of Escherichia coli and Streptococcus faecalis. H...

  19. Characterization of a Multidrug-Resistant, Novel Bacteroides Genomospecies

    PubMed Central

    Salipante, Stephen J.; Kalapila, Aley; Pottinger, Paul S.; Hoogestraat, Daniel R.; Cummings, Lisa; Duchin, Jeffrey S.; Sengupta, Dhruba J.; Pergam, Steven A.; Cookson, Brad T.

    2015-01-01

    Metronidazole- and carbapenem-resistant Bacteroides fragilis are rare in the United States. We isolated a multidrug-resistant anaerobe from the bloodstream and intraabdominal abscesses of a patient who had traveled to India. Whole-genome sequencing identified the organism as a novel Bacteroides genomospecies. Physicians should be aware of the possibility for concomitant carbapenem- and metronidazole-resistant Bacteroides infections. PMID:25529016

  20. Cloning and characterization of hydrogen uptake genes from Rhizobium leguminosarum.

    PubMed Central

    Leyva, A; Palacios, J M; Mozo, T; Ruiz-Argüeso, T

    1987-01-01

    A gene library of genomic DNA from the hydrogen uptake (Hup)-positive strain 128C53 of Rhizobium leguminosarum was constructed by using the broad-host-range mobilizable cosmid vector pLAFR1. The resulting recombinant cosmids contained insert DNA averaging 21 kilobase pairs (kb) in length. Two clones from the above gene library were identified by colony hybridization with DNA sequences from plasmid pHU1 containing hup genes of Bradyhizobium japonicum. The corresponding recombinant cosmids, pAL618 and pAL704, were isolated, and a region of about 28 kb containing the sequences homologous to B. japonicum hup-specific DNA was physically mapped. Further hybridization analysis with three fragments from pHU1 (5.9-kb HindIII, 2.9-kb EcoRI, and 5.0-kb EcoRI) showed that the overall arrangement of the R. leguminosarum hup-specific region closely parallels that of B. japonicum. The presence of functional hup genes within the isolated cosmid DNA was demonstrated by site-directed Tn5 mutagenesis of the 128C53 genome and analysis of the Hup phenotype of the Tn5 insertion strains in symbiosis with peas. Transposon Tn5 insertions at six different sites spanning 11 kb of pAL618 completely suppressed the hydrogenase activity of the pea bacteroids. Images PMID:2822654

  1. High-Resolution Transcriptomic Analyses of Sinorhizobium sp. NGR234 Bacteroids in Determinate Nodules of Vigna unguiculata and Indeterminate Nodules of Leucaena leucocephala

    PubMed Central

    Li, Yan; Tian, Chang Fu; Chen, Wen Feng; Wang, Lei; Sui, Xin Hua; Chen, Wen Xin

    2013-01-01

    The rhizobium-legume symbiosis is a model system for studying mutualistic interactions between bacteria and eukaryotes. Sinorhizobium sp. NGR234 is distinguished by its ability to form either indeterminate nodules or determinate nodules with diverse legumes. Here, we presented a high-resolution RNA-seq transcriptomic analysis of NGR234 bacteroids in indeterminate nodules of Leucaena leucocephala and determinate nodules of Vigna unguiculata. In contrast to exponentially growing free-living bacteria, non-growing bacteroids from both legumes recruited several common cellular functions such as cbb3 oxidase, thiamine biosynthesis, nitrate reduction pathway (NO-producing), succinate metabolism, PHB (poly-3-hydroxybutyrate) biosynthesis and phosphate/phosphonate transporters. However, different transcription profiles between bacteroids from two legumes were also uncovered for genes involved in the biosynthesis of exopolysaccharides, lipopolysaccharides, T3SS (type three secretion system) and effector proteins, cytochrome bd ubiquinol oxidase, PQQ (pyrroloquinoline quinone), cytochrome c550, pseudoazurin, biotin, phasins and glycolate oxidase, and in the metabolism of glutamate and phenylalanine. Noteworthy were the distinct expression patterns of genes encoding phasins, which are thought to be involved in regulating the surface/volume ratio of PHB granules. These patterns are in good agreement with the observed granule size difference between bacteroids from L. leucocephala and V. unguiculata. PMID:23936444

  2. Bacteroides sartorii is an earlier heterotypic synonym of Bacteroides chinchillae and has priority.

    PubMed

    Sakamoto, Mitsuo; Ohkuma, Moriya

    2012-06-01

    Strains of the recently proposed species Bacteroides chinchillae share more than 99.4 % 16S rRNA gene sequence similarity with the type strain of Bacteroides sartorii although these two species do not appear to be similar from their published descriptions. The aim of this study was to perform phenotypic and genetic analyses of both species to clarify their taxonomic position. B. chinchillae JCM 16497(T) exhibited high hsp60 gene sequence similarity with B. sartorii JCM 17136(T) (100 %) as well as B. chinchillae JCM 16498 (100 %). The hsp60 gene sequence analysis and levels of DNA-DNA relatedness observed demonstrated B. sartorii JCM 17136(T), B. chinchillae JCM 16497(T), and B. chinchillae JCM 16498 are members of a single species. Based on these data, we propose Bacteroides chinchillae as a later heterotypic synonym of Bacteroides sartorii. An emended description of B. sartorii is provided. PMID:21764984

  3. Interaction of Bacteroides fragilis and Bacteroides thetaiotaomicron with the kallikrein–kinin system

    PubMed Central

    Mörgelin, Matthias; Cooney, Jakki C.; Frick, Inga-Maria

    2011-01-01

    Many bacterial pathogens interfere with the contact system (kallikrein–kinin system) in human plasma. Activation of this system has two consequences: cleavage of high-molecular-mass kininogen (HK) resulting in release of the potent proinflammatory peptide bradykinin, and initiation of the intrinsic pathway of coagulation. In this study, two species of the Gram-negative anaerobic commensal organism Bacteroides, namely Bacteroides fragilis and Bacteroides thetaiotaomicron, were found to bind HK and fibrinogen, the major clotting protein, from human plasma as shown by immunoelectron microscopy and Western blot analysis. In addition, these Bacteroides species were capable of activating the contact system at its surface leading to a significant prolongation of the intrinsic coagulation time and also to the release of bradykinin. Members of the genus Bacteroides have been known to act as opportunistic pathogens outside the gut, with B. fragilis being the most common isolate from clinical infections, such as intra-abdominal abscesses and bacteraemia. The present results thus provide more insight into how Bacteroides species cause infection. PMID:21527472

  4. Molecular Investigations of Bacteroides as Microbial Source Tracking Tools in Southeast Louisiana Watersheds

    NASA Astrophysics Data System (ADS)

    Schulz, C. J.; Childers, G. W.; Engel, A. S.

    2006-12-01

    Microbial Source Tracking (MST) is a developing field that is gaining increased attention. MST refers to a host of techniques that discriminates among the origins of fecal material found in natural waters from different sources (e.g. human, livestock, and wildlife) by using microbial indicator species with specificity to only certain host organisms. The development of species-specific molecular markers would allow for better evaluation of public health risks and tracking of nutrient sources impacting a watershed. Although several MST methods have been reported with varying levels of success, few offer general applicability for natural waters due to spatial and temporal constraints associated with these methods. One group of molecular MST markers that show promise for broad environmental applications are molecular 16S rDNA probes for Bacteroides. This method is based on 16S rDNA detection directly from environmental samples without the need for a preliminary cultivation step. In this study we have expanded previous sampling efforts to compile a database of over 1000 partial 16S rRNA Bacteroides genes retrieved from the fecal material of 15 different host species (human, cat, dog, pig, kangaroo). To characterize survival of Bacteroides outside of the host, survival time of the Bacteroides marker was compared to that of E.coli under varying natural environmental conditions (temperature and salinity). Bacteroides displayed a survival curve with shouldering and tailing similar to that of E.coli, but log reduction times differed with treatment. In summary, MST marker stability was identified within host species and the overall Bacteroides community structure correlated to host diet, suggesting that detection of a Bacteroides community could confidently identify fecal contamination point sources. Natural water samples from southeast Louisiana were collected for MST including the Tangipahoa River watershed where the source of fecal contamination has been hotly debated. The

  5. Genome-wide transcript analysis of Bradyrhizobium japonicum bacteroids in soybean root nodules.

    PubMed

    Pessi, Gabriella; Ahrens, Christian H; Rehrauer, Hubert; Lindemann, Andrea; Hauser, Felix; Fischer, Hans-Martin; Hennecke, Hauke

    2007-11-01

    The transcriptome of endosymbiotic Bradyrhizobium japonicum bacteroids was assessed, using RNA extracted from determinate soybean root nodules. Results were compared with the transcript profiles of B. japonicum cells grown in either aerobic or microaerobic culture. Microoxia is a known trigger for the induction of symbiotically relevant genes. In fact, one third of the genes induced in bacteroids at day 21 after inoculation are congruent with those up-regulated in culture by a decreased oxygen concentration. The other induced genes, however, may be regulated by cues other than oxygen limitation. Both groups of genes provide a rich source for the possible discovery of novel functions related to symbiosis. Samples taken at different timepoints in nodule development have led to the distinction of genes expressed early and late in bacteroids. The experimental approach applied here is also useful for B. japonicum mutant analyses. As an example, we compared the transcriptome of wild-type bacteroids with that of bacteroids formed by a mutant defective in the RNA polymerase transcription factor sigma54. This led to a collection of hitherto unrecognized B. japonicum genes potentially transcribed in planta in a sigma54-dependent manner. PMID:17977147

  6. Rapid glutamic acid decarboxylase test for identification of Bacteroides and Clostridium spp.

    PubMed Central

    Jilly, B J; Schreckenberger, P C; LeBeau, L J

    1984-01-01

    A rapid 4-h test for glutamic acid decarboxylase is described for the identification of certain anaerobic bacteria. The test substrate consisted of 1.0 g of L-glutamic acid, 0.3 ml of Triton X-155, and 0.05 g of bromcresol green sodium salt in 1 liter of water. The substrate was dispensed in 0.5-ml amounts into test tubes, and a turbid suspension was made with the test organism. The test was then incubated aerobically at 35 degrees C for 4 h. The development of a blue color was considered positive. A total of 345 strains of clinically isolated anaerobic bacteria were tested. All isolates of Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides uniformis. Clostridium perfringens, and Clostridium sordellii gave a positive reaction. Some isolates of Bacteroides distasonis and Bacteroides vulgatus were also positive. The use of this rapid test in conjunction with other rapid methods, such as the spot indol test, will enable laboratory workers to report these pathogens on the same day on which an inoculum of pure culture growth on agar is available. PMID:6376535

  7. [Structure of surface glycoconjugates or Rhizobium species and their function in nitrogen fixation]; Progress report

    SciTech Connect

    1991-01-01

    Lipopolysaccharides (LPS) were isolated and purified from the surface of the Rhizobium species R. trifolii, R. leguminosarium and R. meliloti. A novel core tetrasaccharide and a trisaccharide required for nodulation were discovered. Several types of LPS from a single culture, inducible by nod gene inducers, were resolved by electrophoresis and chromatography. Other potential inducers are being investigated. At least three separate loci control LPS biosynthesis in R. meliloti. We maintain secreted, sulphated LPS involved in nodulation is attached to the cell surface, and have demonstrated sulphated, lipid-linked carbohydrates on the surface of R. meliloti. Antibodies to purified cell surface carbohydrate oligomers are being prepared. These antibodies will be used to screen bacteria, and also to identify cell surface changes associated with differentiation of a bacteria to a bacteroid.

  8. Effects of culture age on symbiotic infectivity of Rhizobium japonicum.

    PubMed

    Bhuvaneswari, T V; Mills, K K; Crist, D K; Evans, W R; Bauer, W D

    1983-01-01

    The infectivity of the soybean symbiont Rhizobium japonicum changed two- to fivefold with culture age for strains 110 ARS, 138 Str Spc, and 123 Spc, whereas culture age had relatively little effect on the infectivity of strains 83 Str and 61A76 Str. Infectivity was measured by determining the number of nodules which developed on soybean primary roots in the zone which contained developing and preemergent root hairs at the time of inoculation. Root cells in this region of the host root are susceptible to Rhizobium infection, but this susceptibility is lost during acropetal development and maturation of the root cells within a period of 4 to 6 h (T. V. Bhuvaneswari, B. G. Turgeon, and W. D. Bauer, Plant Physiol. 66:1027-1031, 1980). Profiles of nodulation frequency at different locations on the root were not affected by the age of the R. japonicum cultures, indicating that culture age affected the efficiency of Rhizobium infection rather than how soon infections were initiated after inoculation. Inoculum dose-response experiments also indicated that culture age affected the efficiency of infection. Two strains, 61A76 Str and 83 Str, were relatively inefficient at all culture ages, particularly at low inoculum doses. Changes in infectivity with culture age were reasonably well correlated with changes in the proportion of cells in a culture capable of binding soybean lectin. Suspensions of R. japonicum in water were found to retain their viability and infectivity. PMID:6681538

  9. Effects of culture age on symbiotic infectivity of Rhizobium japonicum

    SciTech Connect

    Bhuvaneswari, T.V.; Mills, K.K.; Crist, D.K.; Evans, W.R.; Bauer, W.D.

    1983-01-01

    The infectivity of the soybean symbiont Rhizobium japonicum changed two- to fivefold with culture age for strains 110 ARS, 138 Str Spc, and 123 Spc, whereas culture age had relatively little effect on the infectivity of strains 83 Str and 61A76 Str. Infectivity was measured by determining the number of nodules which developed on soybean primary roots in the zone which contained developing and preemergent root hairs at the time of inoculation. Root cells in this region of the host root are susceptible to Rhizobium infection, but this susceptibility is lost during acropetal development and maturation of the root cells within a period of 4 to 6 h. Profiles of nodulation frequency at different locations on the root were not affected by the age of the R. japonicum cultures, indicating that culture age affected the efficiency of Rhizobium infection rather than how soon infections were initiated after inoculation. Inoculum dose-response experiments also indicated that culture age affected the efficiency of infection. Two strains, 61A76 Str and 83 Str, were relatively inefficient at all culture ages, particularly at low inoculum doses. Changes in infectivity with culture age were reasonably well correlated with changes in the proportion of cells in a culture capable of binding soybean lectin. Suspensions of R. japonicum in water were found to retain their viability and infectivity. 15 references, 6 figures, 2 tables.

  10. Rhizobium meliloti Genes Encoding Catabolism of Trigonelline Are Induced under Symbiotic Conditions.

    PubMed

    Boivin, C.; Camut, S.; Malpica, C. A.; Truchet, G.; Rosenberg, C.

    1990-12-01

    Rhizobium meliloti trc genes controlling the catabolism of trigonelline, a plant secondary metabolite often abundant in legumes, are closely linked to nif-nod genes on the symbiotic megaplasmid pSym [Boivin, C., Malpica, C., Rosenberg, C., Denarie, J., Goldman, A., Fleury, V., Maille, M., Message, B., and Tepfer, D. (1989). In Molecular Signals in the Microbe-Plant Symbiotic and Pathogenic Systems. (Berlin: Springer-Verlag), pp. 401-407]. To investigate the role of trigonelline catabolism in the Rhizobium-legume interaction, we studied the regulation of trc gene expression in free-living and in endosymbiotic bacteria using Escherichia coli lacZ as a reporter gene. Experiments performed with free-living bacteria indicated that trc genes were organized in at least four transcription units and that the substrate trigonelline was a specific inducer for three of them. Noninducing trigonelline-related compounds such as betaines appeared to antagonize the inducing effect of trigonelline. None of the general or symbiotic regulatory genes ntrA, dctB/D, or nodD seemed to be involved in trigonelline catabolism. trc fusions exhibiting a low basal and a high induced [beta]-galactosidase activity when present on pSym were used to monitor trc gene expression in alfalfa tissue under symbiotic conditions. Results showed that trc genes are induced during all the symbiotic steps, i.e., in the rhizosphere, infection threads, and bacteroids of alfalfa, suggesting that trigonelline is a nutrient source throughout the Rhizobium-legume association. PMID:12354952

  11. USE OF BACTEROIDES PCR-BASED METHODS TO EXAMINE FECAL CONTAMINATION SOURCES IN TROPICAL COASTAL WATERS

    EPA Science Inventory

    Several library independent Microbial Source Tracking methods have been developed to rapidly determine the source of fecal contamination. Thus far, none of these methods have been tested in tropical marine waters. In this study, we used a Bacteroides 16S rDNA PCR-based...

  12. Conserved nodulation genes in Rhizobium meliloti and Rhizobium trifolii

    SciTech Connect

    Fisher, R.F.; Tu, J.K.; Long, S.R.

    1985-06-01

    Plasmids which contained wild-type or mutated Rhizobium meliloti nodulation (Nod) genes were introduced into Nod/sup -/ R. trifolii mutants ANU453 and ANU851 and tested for their ability to nodulate clover. Cloned wild-type and mutated R. meliloti Nod gene segments restored ANU851 to Nod/sup +/, with the exception of nodD mutants. Similarly, wild-type and mutant R. meliloti nod genes complemented ANU453 to Nod/sup +/, except for nod CII mutants. Thus, ANU851 identifies the equivalent of the R. meliloti nodD genes, and ANU453 specifies the equivalent of the R. meliloti nodCII genes. In addition, cloned wild-type R. trifolii nod genes were introduced into seven R. meliloti Nod/sup -/ mutants. All seven mutants were restored to Nod/sup +/ on alfalfa. Our results indicate that these genes represent common nodulation functions and argue for an allelic relationship between nod genes in R. meliloti and R. trifolii.

  13. Products of dark CO sub 2 fixation in pea root nodules support bacteroid metabolism. [Pisum sativum L

    SciTech Connect

    Rosendahl, L.; Pedersen, W.B. ); Vance, C.P. )

    1990-05-01

    Products of the nodule cytosol in vivo dark ({sup 14}C)CO{sub 2} fixation were detected in the plant cytosol as well as in the bacteroids of pea (Pisum sativum L. cv Bodil) nodules. The distribution of the metabolites of the dark CO{sub 2} fixation products was compared in effective (fix{sup +}) nodules infected by a wild-type Rhizobium leguminosarum (MNF 300), and ineffective (fix{sup {minus}}) nodules of the R. leguminosarum mutant MNF 3080. The latter has a defect in the dicarboxylic acid transport system of the bacterial membrane. The {sup 14}C incorporation from ({sup 14}C)CO{sub 2} was about threefold greater in the wild-type nodules than in the mutant nodules. Similarly, in wild-type nodules the in vitro phosphoenolpyruvate carboxylase activity was substantially greater than that of the mutant. Almost 90% of the {sup 14}C label in the cytosol was found in organic acids in both symbioses. The results indicate a central role for nodule cytosol dark CO{sub 2} fixation in the supply of the bacteroids with dicarboxylic acids.

  14. Activities of Nigerian chewing stick extracts against Bacteroides gingivalis and Bacteroides melaninogenicus.

    PubMed

    Rotimi, V O; Laughon, B E; Bartlett, J G; Mosadomi, H A

    1988-04-01

    The in vitro activities of extracts of Nigerian chewing sticks against Bacteroides gingivalis and B. melaninogenicus are presented. The greatest inhibitory action was produced by Serindeia werneckei, whereas Fagara zanthoxyloides produced no appreciable inhibitory effect. A generally good correlation was found between the killing curves and MICs. Only extracts of Anogeissus leiocarpus showed acute toxicity in mice. PMID:2897830

  15. Activities of Nigerian chewing stick extracts against Bacteroides gingivalis and Bacteroides melaninogenicus.

    PubMed Central

    Rotimi, V O; Laughon, B E; Bartlett, J G; Mosadomi, H A

    1988-01-01

    The in vitro activities of extracts of Nigerian chewing sticks against Bacteroides gingivalis and B. melaninogenicus are presented. The greatest inhibitory action was produced by Serindeia werneckei, whereas Fagara zanthoxyloides produced no appreciable inhibitory effect. A generally good correlation was found between the killing curves and MICs. Only extracts of Anogeissus leiocarpus showed acute toxicity in mice. PMID:2897830

  16. Bacteroides plebeius sp. nov. and Bacteroides coprocola sp. nov., isolated from human faeces.

    PubMed

    Kitahara, Maki; Sakamoto, Mitsuo; Ike, Masako; Sakata, Shinji; Benno, Yoshimi

    2005-09-01

    Nine strains of Gram-negative, anaerobic rod were isolated from human faeces. Based on phylogenetic analysis and specific phenotypic characteristics, these strains were included within the Bacteroides cluster and were divided into two clusters. Strains from the two clusters showed 16S rRNA gene sequence similarities of 90.4 and 92.7% to the nearest recognized species, Bacteroides vulgatus. The strains also formed two clusters exhibiting a 16S rRNA gene sequence divergence of approximately 6%. DNA-DNA hybridization studies confirmed that the two novel strain clusters were distinct from each other. Based on the phenotypic and phylogenetic findings, two novel species, Bacteroides plebeius sp. nov. and Bacteroides coprocola sp. nov., are proposed, each representing one of the two strain clusters. The DNA G+C content of the type strains were 43.9 mol% for B. plebeius (M12(T)=JCM 12973(T)=DSM 17135(T)) and 42.4 mol% for B. coprocola (M16(T)=JCM 12979(T)=DSM 17136(T)). PMID:16166722

  17. The arginine deiminase pathway in Rhizobium etli: DNA sequence analysis and functional study of the arcABC genes.

    PubMed Central

    D'Hooghe, I; Vander Wauven, C; Michiels, J; Tricot, C; de Wilde, P; Vanderleyden, J; Stalon, V

    1997-01-01

    Sequence analysis upstream of the Rhizobium etli fixLJ homologous genes revealed the presence of three open reading frames homologous to the arcABC genes of Pseudomonas aeruginosa. The P. aeruginosa arcABC genes code for the enzymes of the arginine deiminase pathway: arginine deiminase, catabolic ornithine carbamoyltransferase (cOTCase), and carbamate kinase. OTCase activities were measured in free-living R. etli cells and in bacteroids isolated from bean nodules. OTCase activity in free-living cells was observed at a different pH optimum than OTCase activity in bacteroids, suggesting the presence of two enzymes with different characteristics and different expression patterns of the corresponding genes. The characteristics of the OTCase isolated from the bacteroids were studied in further detail and were shown to be similar to the properties of the cOTCase of P. aeruginosa. The enzyme has a pH optimum of 6.8 and a molecular mass of approximately 450 kDa, is characterized by a sigmoidal carbamoyl phosphate saturation curve, and exhibits a cooperativity for carbamoyl phosphate. R. etli arcA mutants, with polar effects on arcB and arcC, were constructed by insertion mutagenesis. Bean nodules induced by arcA mutants were still able to fix nitrogen but showed a significantly lower acetylene reduction activity than nodules induced by the wild type. No significant differences in nodule dry weight, plant dry weight, and number of nodules were found between the wild type and the mutants. Determination of the OTCase activity in extracts from bacteroids revealed a strong decrease in activity of this enzyme in the arcA mutant compared to the wild-type strain. Finally, we observed that expression of an R. etli arcA-gusA fusion was strongly induced under anaerobic conditions. PMID:9393705

  18. Bacteroides-associated pylephlebitis in a patient with strongyloidiasis.

    PubMed

    Stone, Neil R H; Martin, Thomas; Biswas, Jason; Barrett, Jessica; Hickish, Tom; Dasgupta, Dhruba; Newsholme, William

    2015-02-01

    Strongyloidiasis is associated with Gram-negative bacteremia. Septic portal vein thrombosis or pylephlebitis is a rare but serious complication of intra-abdominal infection, and it is often associated with Bacteroides bacteremia. We present the first report of pylephlebitis with Bacteroides bacteremia associated with underlying Strongyloides stercoralis infection and briefly review the management of septic portal vein thrombosis. PMID:25510718

  19. Effect of Protein Additives on Acetylene Reduction (Nitrogen Fixation) by Rhizobium in the Presence and Absence of Soybean Cells 1

    PubMed Central

    Anderson, Stephen J.; Phillips, Donald A.

    1976-01-01

    The effect of protein additives on acetylene reduction (N2 fixation) by Rhizobium associated with soybean cells (Glycine max [L.] Merr.) in vitro was studied. Acetylene reduction was promoted on the basal medium supplemented with 1.4 mg of N/ml supplied as aqueous extracts of hexane-extracted soybean, red kidney beans (Phaseolus vulgaris L.), or peas (Pisum sativum L.). Commercial samples of α-casein, or bovine serum albumin also promoted acetylene reduction at a concentration of 1.4 mg of N/ml of basal medium, but egg albumin supplying an equal amount of nitrogen to the basal medium completely suppressed acetylene reduction. Autoclaving the aqueous extract of hexane-extracted soybean meal had no effect on its ability to promote acetylene reduction. The presence of 40 mm succinate decreased acetylene reduction with leguminous proteins supplying 1.4 mg of N/ml but promoted acetylene reduction by Rhizobium 32H1-soybean cell associations on media containing α-casein, bovine serum albumin, or egg albumin suppling 1.4 mg of N/ml. Similar results were obtained with both cowpea Rhizobium 32H1 and Rhizobium japonicum 61A96. Pure cultures of Rhizobium 32H1 developed acetylene-reducing activity in the presence of soybean extract on basal agar medium and in vermiculite supplied with N-free mineral salts plus crude soybean meal. The results suggest that in certain situations, free living Rhizobium may reduce N2 under field conditions. PMID:16659592

  20. The symbiovar trifolii of Rhizobium bangladeshense and Rhizobium aegyptiacum sp. nov. nodulate Trifolium alexandrinum in Egypt.

    PubMed

    Shamseldin, Abdelaal; Carro, Lorena; Peix, Alvaro; Velázquez, Encarna; Moawad, Hassan; Sadowsky, Michael J

    2016-06-01

    In the present work we analyzed the taxonomic status of several Rhizobium strains isolated from Trifolium alexandrinum L. nodules in Egypt. The 16S rRNA genes of these strains were identical to those of Rhizobium bangladeshense BLR175(T) and Rhizobium binae BLR195(T). However, the analyses of recA and atpD genes split the strains into two clusters. Cluster II strains are identified as R. bangladeshense with >98% similarity values in both genes. The cluster I strains are phylogenetically related to Rhizobium etli CFN42(T) and R. bangladeshense BLR175(T), but with less than 94% similarity values in recA and atpD genes. DNA-DNA hybridization analysis showed 42% and 48% average relatedness between the strain 1010(T) from cluster I with respect to R. bangladeshense BLR175(T) and R. etli CFN42(T), respectively. Phenotypic characteristics of cluster I strains also differed from those of their closest related Rhizobium species. Analysis of the nodC gene showed that the strains belong to two groups within the symbiovar trifolii which was identified in Egypt linked to the species R. bangladeshense. Based on the genotypic and phenotypic characteristics, the group I strains belong to a new species for which the name Rhizobium aegyptiacum sp. nov. (sv. trifolii) is proposed, with strain 1010(T) being designated as the type strain (= USDA 7124(T)=LMG 29296(T)=CECT 9098(T)). PMID:27236564

  1. Morphogenetic expression of Bacteroides nodosus fimbriae in Pseudomonas aeruginosa.

    PubMed Central

    Mattick, J S; Bills, M M; Anderson, B J; Dalrymple, B; Mott, M R; Egerton, J R

    1987-01-01

    Type 4 fimbriae are found in a range of pathogenic bacteria, including Bacteroides nodosus, Moraxella bovis, Neisseria gonorrhoeae, and Pseudomonas aeruginosa. The structural subunits of these fimbriae all contain a highly conserved hydrophobic amino-terminal sequence preceding a variable hydrophilic carboxy-terminal region. We show here that recombinant P. aeruginosa cells containing the B. nodosus fimbrial subunit gene under the control of a strong promoter (pL, from bacteriophage lambda) produced large amounts of fimbriae that were structurally and antigenically indistinguishable from those produced by B. nodosus. This was demonstrated by fimbrial isolation and purification, electrophoretic and Western transfer analyses, and immunogold labeling and electron microscopy. These results suggest that type 4 fimbriated bacteria use a common mechanism for fimbrial assembly and that the structural subunits are interchangeable, thereby providing a basis for the development of multivalent vaccines. Images PMID:2878919

  2. [The first metronidazole-resistant Bacteroides species isolated at Marmara University Hospital: Bacteroides thetaiotaomicron].

    PubMed

    Toprak Ülger, Nurver; Sayın, Elvan; Soyad, Ad; Dane, Faysal; Söyletir, Güner

    2013-10-01

    Bacteroides species, the predominant constituents of the human intestinal microbiota can cause serious intraabdominal and postoperative wound infections and bacteremia. Moreover, these bacteria are more resistant to antimicrobial agents than the other anaerobes. The limited number of the antimicrobials, such as carbapenems, beta-lactam/beta-lactamase inhibitors and nitroimidazoles are highly effective in eliminating Bacteroides. However, a few metronidazole-resistant isolates have been reported from several countries recently. The nim genes (nim A-G) are suggested to be responsible for the majority of the metronidazole resistance. Here, we describe a metronidazole-resistant Bacteroides thetaiotaomicron isolated from a blood culture. A gram-negative obligate anaerobic rod was isolated from the postoperative 5th day blood culture of a 62-year-old male patient with adenocarcinoma of the pancreas head. The strain was identified as B.thetaiotaomicron by using a combination of conventional tests and commercially available biochemical kits. Antimicrobial susceptibility testing was performed by agar dilution method. The resistance genes were investigated by means of PCR using specific primer pairs for nim gene. The purified PCR product was sequenced and analyzed by comparison of the consensus sequences with GenBank sequences. The MIC for metronidazole was 16 mg/L. Although the strain was intermediate according the CLSI criteria, it was resistant (> 4 mg/L) according to EUCAST criteria. The isolate was nim gene positive, and nucleotide sequencing of the PCR product shared 100% similarity with nimE gene (emb |AM042593.1 |). On the other hand the isolate was susceptible to carbapenems and sulbactam-ampicillin. Following administration of ampicillin-sulbactam, the patient's fever disappeared after 24 hours. The clinical condition improved considerably and he was discharged at day 8. The patient was followed up at the medical oncology clinic; however he died due to disease

  3. Structural Characterization of the Primary O-antigenic Polysaccharide of the Rhizobium leguminosarum 3841 Lipopolysaccharide and Identification of a New 3-Acetimidoylamino-3-deoxyhexuronic Acid Glycosyl Component

    PubMed Central

    Forsberg, L. Scott; Carlson, Russell W.

    2008-01-01

    Rhizobium are Gram-negative bacteria that survive intracellularly, within host membrane-derived plant cell compartments called symbiosomes. Within the symbiosomes the bacteria differentiate to bacteroids, the active form that carries out nitrogen fixation. The progression from free-living bacteria to bacteroid is characterized by physiological and morphological changes at the bacterial surface, a phase shift with an altered array of cell surface glycoconjugates. Lipopolysaccharides undergo structural changes upon differentiation from the free living to the bacteroid (intracellular) form. The array of carbohydrate structures carried on lipopolysaccharides confer resistance to plant defense mechanisms and may serve as signals that trigger the plant to allow the infection to proceed. We have determined the structure of the major O-polysaccharide (OPS) isolated from free living Rhizobium leguminosarum 3841, a symbiont of Pisum sativum, using chemical methods, mass spectrometry, and NMR spectroscopy analysis. The OPS is composed of several unusual glycosyl residues, including 6-deoxy-3-O-methyl-d-talose and 2-acetamido-2deoxy-l-quinovosamine. In addition, a new glycosyl residue, 3-acetimidoylamino-3-deoxy-d-gluco-hexuronic acid was identified and characterized, a novel hexosaminuronic acid that does not have an amino group at the 2-position. The OPS is composed of three to four tetrasaccharide repeating units of →4)-β-dGlcp3NAmA-(1→4)-[2-O-Ac-3-O-Me-α-d-6dTalp-(1→3)]-α-l-Fucp-(1→3)-α-l-QuipNAc-(1→. The unique 3-amino hexuronate residue, rhizoaminuronic acid, is an attractive candidate for selective inhibition of OPS synthesis. PMID:18387959

  4. Localization of aluminum in soybean bacteroids and seeds

    SciTech Connect

    Roth, L.E.; Dunlap, J.R.; Stacey, G.

    1987-10-01

    Aluminum, long known to be detrimental to soybean productivity, was localized in the polyphosphate granules (PPG) of bacteroids in root nodules of soybean plants. By using energy-dispersive X-ray analysis, bacteroids in early infections were shown to have typical PPG constituents. However, in PPG in older infections and after the bacteroids were digested intracellularly, aluminum was also detected. These results indicate that aluminum accumulates in PPG after a period when organisms have been resident in host cells and that high levels of aluminum were present in the bacteroids at the time of their demise. At least some of the aluminum in these laboratory-grown plants could have come from the seeds used.

  5. Characterization of the cycHJKL genes involved in cytochrome c biogenesis and symbiotic nitrogen fixation in Rhizobium leguminosarum.

    PubMed Central

    Delgado, M J; Yeoman, K H; Wu, G; Vargas, C; Davies, A E; Poole, R K; Johnston, A W; Downie, J A

    1995-01-01

    Mutants of Rhizobium leguminosarum bv. viciae unable to respire via the cytochrome aa3 pathway were identified by the inability to oxidize N,N'-dimethyl-p-phenylenediamine. Two mutants which were complemented by cosmid pIJ1942 from an R. leguminosarum clone bank were identified. Although pea nodules induced by these mutants contained many bacteroids, no symbiotic nitrogen fixation was detected. Heme staining of cellular proteins revealed that all cytochrome c-type heme proteins were absent. These mutants lacked spectroscopically detectable cytochrome c, but cytochromes aa3 and d were present, the latter at a higher-than-normal level. DNA sequence analysis of complementing plasmids revealed four apparently cotranscribed open reading frames (cycH, cycJ, cycK, and cycL). CycH, CycJ, CycK, and CycL are homologous to Bradyrhizobium japonicum and Rhizobium meliloti proteins thought to be involved in the attachment of heme to cytochrome c apoproteins; CycK and CycL are also homologous to the Rhodobacter capsulatus ccl1 and ccl2 gene products and the Escherichia coli nrfE and nrfF gene products involved in the assembly of c-type cytochromes. The absence of cytochrome c heme proteins in these R. leguminosarum mutants is consistent with the view that the cycHJKL operon could be involved in the attachment of heme to apocytochrome c. PMID:7665469

  6. Rapid and correct identification of intestinal Bacteroides spp. with chromosomal DNA probes by whole-cell dot blot hybridization

    SciTech Connect

    Morotomi, M.; Ohno, T.; Mutai, M.

    1988-05-01

    A dot blot hybridization procedure with /sup 32/P-labeled whole chromosomal DNA of the type strains as probes was developed as a rapid and simple method for identification of intestinal Bacteroides species. Bacterial cells were fixed onto membrane filters by slight suction, treated with 0.5 N NaOH, and hybridized with these probes. Of 65 Bacteroides strains isolated from 19 human fecal specimens, which were identified as B. fragilis, B. thetaiotaomicron, B. ovatus, B. caccae, B. uniformis, B. stercoris, B. vulgatus, B. distasonis, and B. merdae by conventional phenotypic characterization, 62 (95%) were correctly identified with this hybridization procedure.

  7. Polyethylene glycol-facilitated transformation of Bacteroides fragilis with plasmid DNA

    SciTech Connect

    Smith, C.J.

    1985-10-01

    A method for the transformation of Bacteroides fragilis with plasmid DNA was developed by using the clindamycin resistance plasmid pBFTM10 as the source of transforming DNA. The method was technically simple to perform and resulted in an average of 4.2 x 10/sup 3/ tranformants per ..mu..g of pBFTM10 added. A method for the preparation of frozen competent cells is also described.

  8. Host-symbiont interactions-V. The structure of acidic extracellular polysaccharides secreted by Rhizobium leguminosarum and Rhizobium trifolii

    SciTech Connect

    Robertsen, B.K.; Aman, P.; Darvill, A.G.; McNeil, M.; Albersheim, P.

    1981-01-01

    The sequence of the glycosyl residues and the anomeric configurations of the glycosl linkages of the acidic polysaccharides secreted by Rhizobium leguminosarum 128c53, Rhizobium leguminosarum 128c63, Rhizobium trifolii NA30, and Rhizobium trifolii 0403 have been determined. Each of the glycosyl residues of these polysaccharides was determined to be in the D configuration and in the pyranose ring form. These results add support to the proposal that R. leguminosarum and R. trifolii have a particularly close genetic relationship. The significance of these results with regard to the possible function of these polysaccharides in the nodulation process is discussed. (JMT)

  9. Bacteroides gingivalis and Bacteroides intermedius recognize different sites on human fibrinogen

    SciTech Connect

    Lantz, M.S.; Allen, R.D.; Bounelis, P.; Switalski, L.M.; Hook, M. )

    1990-02-01

    Bacteroides (Porphyromonas) gingivalis and Bacteroides (Porphyromonas) intermedius have been implicated in the etiology of human periodontal diseases. These organisms are able to bind and degrade human fibrinogen, and these interactions may play a role in the pathogenesis of periodontal disease. In attempts to map the bacterial binding sites along the fibrinogen molecule, we have found that strains of B. gingivalis and B. intermedius, respectively, recognize spatially distant and distinct sites on the fibrinogen molecule. Isolated reduced and alkylated alpha-, beta-, and gamma-fibrinogen chains inhibited binding of 125I-fibrinogen to both Bacteroides species in a concentration-dependent manner. Plasmin fragments D and to some extent fragment E, however, produced a concentration-dependent inhibition of 125I-fibrinogen binding to B. intermedius strains but did not affect binding of 125I-fibrinogen to B. gingivalis strains. Radiolabeled fibrinogen chains and fragments were compared with 125I-fibrinogen with respect to specificity and reversibility of binding to bacteria. According to these criteria, gamma chain most closely resembled the native fibrinogen molecule in behavior toward B. gingivalis strains and fragments D most closely resembled fibrinogen in behavior toward B. intermedius strains. The ability of anti-human fibrinogen immunoglobulin G (IgG) to inhibit binding of 125I-fibrinogen to B. intermedius strains was greatly reduced by absorbing the IgG with fragments D. Absorbing the IgG with fragments D had no effect on the ability of the antibody to inhibit binding of 125I-fibrinogen to B. gingivalis strains. A purified staphylococcal fibrinogen-binding protein blocked binding of 125I-fibrinogen to B. intermedius strains but not to B. gingivalis strains.

  10. A Novel Tightly Regulated Gene Expression System for the Human Intestinal Symbiont Bacteroides thetaiotaomicron

    PubMed Central

    Horn, Nikki; Carvalho, Ana L.; Overweg, Karin; Wegmann, Udo; Carding, Simon R.; Stentz, Régis

    2016-01-01

    There is considerable interest in studying the function of Bacteroides species resident in the human gastrointestinal (GI)-tract and the contribution they make to host health. Reverse genetics and protein expression techniques, such as those developed for well-characterized Escherichia coli cannot be applied to Bacteroides species as they and other members of the Bacteriodetes phylum have unique promoter structures. The availability of useful Bacteroides-specific genetic tools is therefore limited. Here we describe the development of an effective mannan-controlled gene expression system for Bacteroides thetaiotaomicron containing the mannan-inducible promoter–region of an α-1,2-mannosidase gene (BT_3784), a ribosomal binding site designed to modulate expression, a multiple cloning site to facilitate the cloning of genes of interest, and a transcriptional terminator. Using the Lactobacillus pepI as a reporter gene, mannan induction resulted in an increase of reporter activity in a time- and concentration-dependent manner with a wide range of activity. The endogenous BtcepA cephalosporinase gene was used to demonstrate the suitability of this novel expression system, enabling the isolation of a His-tagged version of BtCepA. We have also shown with experiments performed in mice that the system can be induced in vivo in the presence of an exogenous source of mannan. By enabling the controlled expression of endogenous and exogenous genes in B. thetaiotaomicron this novel inducer-dependent expression system will aid in defining the physiological role of individual genes and the functional analyses of their products. PMID:27468280

  11. Nutritional features of Bacteroides fragilis subsp. fragilis.

    PubMed

    Varel, V H; Bryant, M P

    1974-08-01

    Studies of three reference strains of Bacteroides fragilis subsp. fragilis showed that they grow well in a minimal defined medium containing glucose, hemin, vitamin B(12), minerals, bicarbonate-carbon dioxide buffer, NH(4)Cl, and sulfide. The vitamin B(12) requirement of 0.1 ng/ml was replaced with 7.5 mug of methionine. Cysteine or sulfide was an excellent source of sulfur, thioglycolate was a poor source, and thiosulfate, methionine, beta-mercaptoethanol, dithiothreitol, sulfate, or sulfite did not serve as sole sources of sulfur. Neither single amino acids, nitrate, urea, nor a complex mixture of L-amino acids or peptides effectively replaced ammonia as the nitrogen source. Comparative studies with a few strains of other subspecies of B. fragilis including B. fragilis subsp. vulgatus, B. fragilis subsp. thetaiotaomicron, and B. fragilis subsp. distasonis indicate that they exhibit similar growth responses in the minimal medium. A single strain of B. fragilis subsp. ovatus required other materials. The results indicate the great biosynthetic ability of these organisms and suggest that, in their ecological niche within the large intestine, many nutrients such as amino acids are in very low supply, whereas materials such as ammonia, heme, and vitamin B(12), or related compounds, must be available during much of the time. PMID:4853401

  12. Design and evaluation of Bacteroides DNA probes for the specific detection of human fecal pollution.

    PubMed Central

    Kreader, C A

    1995-01-01

    Because Bacteroides spp. are obligate anaerobes that dominate the human fecal flora, and because some species may live only in the human intestine, these bacteria might be useful to distinguish human from nonhuman sources of fecal pollution. To test this hypothesis, PCR primers specific for 16S rRNA gene sequences of Bacteroides distasonis, B. thetaiotaomicron, and B. vulgatus were designed. Hybridization with species-specific internal probes was used to detect the intended PCR products. Extracts from 66 known Bacteroides strains, representing 10 related species, were used to confirm the specificity of these PCR-hybridization assays. To test for specificity in feces, procedures were developed to prepare DNA of sufficient purity for PCR. Extracts of feces from 9 humans and 70 nonhumans (cats, dogs, cattle, hogs, horses, sheep, goats, and chickens) were each analyzed with and without an internal positive control to verify that PCR amplification was not inhibited by substances in the extract. In addition, serial dilutions from each extract that tested positive were assayed to estimate the relative abundance of target Bacteroides spp. in the sample. Depending on the primer-probe set used, either 78 or 67% of the human fecal extracts tested had high levels of target DNA. On the other hand, only 7 to 11% of the nonhuman extracts tested had similarly high levels of target DNA. An additional 12 to 20% of the nonhuman extracts had levels of target DNA that were 100- to 1,000-fold lower than those found in humans.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7538270

  13. Design and evaluation of Bacteroides DNA probes for the specific detection of human fecal pollution

    SciTech Connect

    Kreader, C.A.

    1995-04-01

    Because Bacteroides spp. are obligate anaerobes that dominate the human fecal flora, and because some species may live only in the human intestine, these bacteria might be useful to distinguish human from nonhuman sources of fecal pollution. To test this hypothesis, PCR primers specific for 16S rRNA gene sequences of Bacteroides distasonis, B. thetaiotaomicron, and B. vulgatus were designed. Hybridization with species-specific internal probes was used to detect the intended PCR products. Extracts from 66 known Bacteroides strains, representing 10 related species, were used to confirm the specificity of these PCR-hybridization assays. To test for specificity in feces, procedures were developed to prepare DNA of sufficient purity for PCR. Extracts of feces from 9 humans and 70 nonhumans (cats, dogs, cattle, hogs, horses, sheep, goats, and chickens) were each analyzed with and without an internal positive control to verify that PCR amplification was not inhibited by substances in the extract. In addition, serial dilutions from each extract that tested positive were assayed to estimate the relative abundance of target Bacteroides spp. in the sample. Depending on the primer-probe set used, either 78 or 67% of the human fecal extracts tested had high levels of target DNA. On the other hand, only 7 to 11% of the nonhuman extracts tested had similarly high levels of target DNA. An additional 12 to 20% of the nonhuman extracts had levels of target DNA that were 100- to 1,000-fold lower than those found in humans. Although the B. vulgatus probes detected high levels of their target DNA in most of the house pets, similarly high levels of target DNA were found only in a few individuals from other groups of nonhumans. Therefore, the results indicate that these probes can distinguish human from non human feces in many cases. 50 refs., 5 figs., 2 tabs.

  14. Cytotoxic and immunostimulatory effects of Bacteroides cell products.

    PubMed

    Fotos, P G; Lewis, D M; Gerencser, V F; Gerencser, M A

    1990-09-01

    The etiologic role of Bacteroides in both periodontal and periapical infections has been well documented, with current interest focusing on the specific pathogenic mechanisms involved. The effects of cell fractions derived from Bacteroides gingivalis (BG), Bacteroides intermedius (BI), and Bacteroides asaccharolyticus (BA) have been studied in vitro through: an assessment of the direct cytotoxic effects on human gingival fibroblasts using a tetrazolium dye reduction assay, an evaluation of murine lymphocyte stimulation and interleukin-1 release, and the induction of human lymphocyte-mediated cytotoxicity. Both BG and BI stimulated interleukin-1 release (P less than 0.001), while BA, a nonoral organism, was not significantly active in this respect. Only BG sonicates were able to induce lymphocyte-mediated cytotoxicity (P less than 0.005). All three Bacteroides species demonstrated direct cytotoxic effects on cultured gingival fibroblasts, and these effects were related to the relative protein content and endotoxin activity of the sonicate preparations for each organism. These data show that BG and BI possess factors which may enhance their virulence through activities not shared with BA. PMID:2250226

  15. Amino Acid and Vitamin Requirements of Several Bacteroides Strains

    PubMed Central

    Quinto, Grace

    1966-01-01

    Nutritional studies were performed on nine Bacteroides strains, by use of the methodology and media of anaerobic rumen microbiology. Ristella perfoetens CCI required l-arginine hydrochloride, l-tryptophan, l-leucine, l-histidine hydrochloride, l-cysteine hydrochloride, dl-valine, dl-tyrosine, and the vitamin calcium-d-pantothenate, since scant turbidity developed in media without these nutrients. R. perfoetens was stimulated by glycine, dl-lysine hydrochloride, dl-isoleucine, l-proline, l-glutamic acid, dl-alanine, dl-phenylalanine, dl-methionine, and the vitamins nicotinamide and p-aminobenzoic acid, since maximal turbidity developed more slowly in media without these nutrients than in complete medium. Medium A-23, which was devised for R. perfoetens, contained salts, 0.0002% nicotinamide and calcium d-pantothenate, 0.00001% p-aminobenzoic acid, 0.044% l-tryptophan, 0.09% l-glutamic acid, and 0.1% of the other 13 amino acids listed above. Zuberella clostridiformis and seven strains of R. pseudoinsolita did not require vitamins, and showed no absolute requirement for any one amino acid. Various strains produced maximal turbidity more slowly in media deficient in l-proline, glycine, l-glutamic acid, dl-serine, l-histidine hydrochloride, dl-alanine, or l-cysteine hydrochloride, than in complete medium. These eight strains grew optimally in medium A-23 plus 0.1% dl-serine but without vitamins. PMID:16349673

  16. An osmoregulated dipeptide in stressed Rhizobium meliloti.

    PubMed Central

    Smith, L T; Smith, G M

    1989-01-01

    One common mechanism of cellular adaptation to osmotic stress is the accumulation of organic solutes in the cytosol. We have used natural-abundance 13C nuclear magnetic resonance to identify all organic solutes that accumulate to significant levels in Rhizobium meliloti. Our studies led to the discovery of a new dipeptide, N-acetylglutaminylglutamine amide (NAGGN), which is accumulated during osmotic stress. Only rarely have peptides been shown to function in bacteria, and furthermore, this is the first example of a peptide playing a role in osmoregulation. Evidence for the biological role of NAGGN in osmotic-stress protection is presented. PMID:2768187

  17. (Analysis of the Rhizobium meliloti surface):

    SciTech Connect

    Signer, E.R.

    1988-03-03

    We have identified a number of genes in Rhizobium meliloti that affect outer membrane lipopolysaccharides (LPS). These include three genes defined by mutants with different patterns of resistance to a panel of bacteriophages, of which Class 2 and 3 are closely linked to each other but not to Class 1 or 4;another gene, closely linked to Class 2 and 3, defined only by its ability to suppress Class 1 defects;and three genes, unlinked to each other, defined by mutants with increased sensitivity to deoxycholate. Of the mutants that define these genes, only those in Class 2 have a clear effect on alfalfa symbiosis, having a Fix phenotype.

  18. Variability among Rhizobium Strains Originating from Nodules of Vicia faba.

    PubMed

    van Berkum, P; Beyene, D; Vera, F T; Keyser, H H

    1995-07-01

    Rhizobium strains from nodules of Vicia faba were diverse in plasmid content and serology. Results of multilocus gel electrophoresis and restriction fragment length polymorphism indicated several deep chromosomal lineages among the strains. Linkage disequilibrium among the chromosomal types was detected and may have reflected variation of Rhizobium strains in the different geographical locations from which the strains originated. An investigation of pea strains with antibodies prepared against fava bean strains and restriction fragment length polymorphism analyses, targeting DNA regions coding for rRNA and nodulation, indicated that Rhizobium strains from V. faba nodules were distinguishable from those from Pisum sativum, V. villosa, and Trifolium spp. PMID:16535075

  19. Growth of fast- and slow-growing rhizobia on ethanol. [Bradyrhizobium sp. ; Rhizobium meliloti; Rhizobium loti; Rhizobium leguminosarum; Rhizobium fredii; Bradyrhizobium japonicum

    SciTech Connect

    Sadowsky, M.J.; Bohlool, B.B.

    1986-10-01

    Free-living soybean rhizobia and Bradyrhizobium spp. (lupine) have the ability to catabolize ethanol. Of the 30 strains of rhizobia examined, only the fast- and slow-growing soybean rhizobia and the slow-growing Bradyrhizobium sp (lupine) were capable of using ethanol as a sole source of carbon and energy for growth. Two strains from each of the other Rhizobium species examined (R. meliloti, R. loti, and R. leguminosarum biovars phaseoli, trifolii, and viceae) failed to grow on ethanol. One Rhizobium fredii (fast-growing) strain, USDA 191, and one (slow-growing) Bradyrhizobium japonicum strain, USDA 110, grew in ethanol up to concentrations of 3.0 and 1.0%, respectively. While three of the R. fredii strains examined (USDA 192, USDA 194, and USDA 205) utilized 0.2% acetate, only USDA 192 utilized 0.1% n-propanol. None of the three strains utilized 0.1% methanol, formate, or n-butanol as the sole carbon source.

  20. Identification of Rhizobium-specific intergenic mosaic elements within an essential two-component regulatory system of Rhizobium species.

    PubMed Central

    Osterås, M; Stanley, J; Finan, T M

    1995-01-01

    Analysis of the DNA regions upstream of the phosphoenolpyruvate carboxykinase gene (pckA) in Rhizobium meliloti and Rhizobium sp. strain NGR234 identified an open reading frame which was highly homologous to the Agrobacterium tumefaciens chromosomal virulence gene product ChvI. A second gene product, 500 bp downstream of the chvI-like gene in R. meliloti, was homologous to the A. tumefaciens ChvG protein. The homology between the R. meliloti and A. tumefaciens genes was confirmed, because the R. meliloti chvI and chvG genes complemented A. tumefaciens chvI and chvG mutants for growth on complex media. We were unable to construct chvI or chvG insertion mutants of R. meliloti, whereas mutants carrying insertions outside of these genes were readily obtained. A 108-bp repeat element characterized by two large palindromes was identified in the chvI and chvG intergenic regions of both Rhizobium species. This element was duplicated in Rhizobium sp. strain NGR234. Another structurally similar element with a size of 109 bp was present in R. meliloti but not in Rhizobium sp. strain NGR234. These elements were named rhizobium-specific intergenic mosaic elements (RIMEs), because their distribution seems to be limited to members of the family Rhizobiaceae. A homology search in GenBank detected six more copies of the first element (RIME1), all in Rhizobium species, and three extra copies of the second element (RIME2), only in R. meliloti. Southern blot analysis with a probe specific to RIME1 showed the presence of several copies of the element in the genome of R. meliloti, Rhizobium sp. strain NGR234, Rhizobium leguminosarum, and Agrobacterium rhizogenes, but none was present in A. tumefaciens and Bradyrhizobium japonicum. PMID:7559334

  1. Studying Plant-Rhizobium Mutualism in the Biology Classroom: Connecting the Big Ideas in Biology through Inquiry

    ERIC Educational Resources Information Center

    Suwa, Tomomi; Williamson, Brad

    2014-01-01

    We present a guided-inquiry biology lesson, using the plant-rhizobium symbiosis as a model system. This system provides a rich environment for developing connections between the big ideas in biology as outlined in the College Board's new AP Biology Curriculum. Students gain experience with the practice of scientific investigation, from…

  2. Bacteroides: the Good, the Bad, and the Nitty-Gritty

    PubMed Central

    Wexler, Hannah M.

    2007-01-01

    Summary: Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin). PMID:17934076

  3. Uptake and Metabolism of Carbohydrates by Bradyrhizobium japonicum Bacteroids 1

    PubMed Central

    Salminen, Seppo O.; Streeter, John G.

    1987-01-01

    Bradyrhizobium japonicum bacteroids were isolated anaerobically and were supplied with 14C-labeled trehalose, sucrose, UDP-glucose, glucose, or fructose under low O2 (2% in the gas phase). Uptake and conversion of 14C to CO2 were measured at intervals up to 90 minutes. Of the five compounds studied, UDP-glucose was most rapidly absorbed but it was very slowly metabolized. Trehalose was the sugar most rapidly converted to CO2, and fructose was respired at a rate at least double that of glucose. Sucrose and glucose were converted to CO2 at a very low but measurable rate (<0.1 nanomoles per milligram protein per hour). Carbon Number 1 of glucose appeared in CO2 at a rate 30 times greater than the conversion of carbon Number 6 to CO2, indicating high activity of the pentose phosphate pathway. Enzymes of the Entner-Doudoroff pathway were not detected in bacteroids, but very low activities of sucrose synthase and phosphofructokinase were demonstrated. Although metabolism of sugars by B. japonicum bacteroids was clearly demonstrated, the rate of sugar uptake was only 1/30 to 1/50 the rate of succinate uptake. The overall results support the view that, although bacteroids metabolize sugars, the rates are very low and are inadequate to support nitrogenase. PMID:16665284

  4. Transposon mutagenesis of Bacteroides fragilis using a mariner transposon vector.

    PubMed

    Veeranagouda, Yaligara; Husain, Fasahath; Wexler, Hannah M

    2013-08-01

    The mariner transposon vector pYV07 was tested for use in the mutagenesis of Bacteroides fragilis 638R. The transposon vector efficiently generated mutants in B. fragilis 638R. The transposon disrupted genes were scattered throughout the genome of B. fragilis 638R. This method serves as a powerful tool to study B. fragilis. PMID:23664906

  5. Differential Decay of Human Faecal Bacteroides in Marine and Freshwater

    EPA Science Inventory

    Gene sequences from Bacteroides and relatives are being considered for the enumeration of aquatic fecal contamination and estimation of public health risk. To interpret these data, it is necessary to understand the decay of molecular and cultivated indicators and pathogens in en...

  6. Effects of nano-TiO₂ on the agronomically-relevant Rhizobium-legume symbiosis.

    PubMed

    Fan, Ruimei; Huang, Yu Chu; Grusak, Michael A; Huang, C P; Sherrier, D Janine

    2014-01-01

    The impact of nano-TiO₂ on Rhizobium-legume symbiosis was studied using garden peas and the compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure to nano-TiO₂ did not affect the germination of peas grown aseptically, nor did it impact the gross root structure. However, nano-TiO₂ exposure did impact plant development by decreasing the number of secondary lateral roots. Cultured R. leguminosarum bv. viciae 3841 was also impacted by exposure to nano-TiO₂, resulting in morphological changes to the bacterial cells. Moreover, the interaction between these two organisms was disrupted by nano-TiO₂ exposure, such that root nodule development and the subsequent onset of nitrogen fixation were delayed. Further, the polysaccharide composition of the walls of infected cells of nodules was altered, suggesting that the exposure induced a systemic response in host plants. Therefore, nano-TiO₂ contamination in the environment is potentially hazardous to the Rhizobium-legume symbiosis system. PMID:23933452

  7. RNA-Seq and Microarrays Analyses Reveal Global Differential Transcriptomes of Mesorhizobium huakuii 7653R between Bacteroids and Free-Living Cells

    PubMed Central

    Peng, Jieli; Hao, Baohai; Liu, Liu; Wang, Shanming; Ma, Binguang; Yang, Yi; Xie, Fuli; Li, Youguo

    2014-01-01

    Mesorhizobium huakuii 7653R occurs either in nitrogen-fixing symbiosis with its host plant, Astragalus sinicus, or free-living in the soil. The M. huakuii 7653R genome has recently been sequenced. To better understand the complex biochemical and developmental changes that occur in 7653R during bacteroid development, RNA-Seq and Microarrays were used to investigate the differential transcriptomes of 7653R bacteroids and free-living cells. The two approaches identified several thousand differentially expressed genes. The most prominent up-regulation occurred in the symbiosis plasmids, meanwhile gene expression is concentrated to a set of genes (clusters) in bacteroids to fulfill corresponding functional requirements. The results suggested that the main energy metabolism is active while fatty acid metabolism is inactive in bacteroid and that most of genes relevant to cell cycle are down-regulated accordingly. For a global analysis, we reconstructed a protein-protein interaction (PPI) network for 7653R and integrated gene expression data into the network using Cytoscape. A highly inter-connected subnetwork, with function enrichment for nitrogen fixation, was found, and a set of hubs and previously uncharacterized genes participating in nitrogen fixation were identified. The results described here provide a broader biological landscape and novel insights that elucidate rhizobial bacteroid differentiation, nitrogen fixation and related novel gene functions. PMID:24695521

  8. Optimization of Dairy Sludge for Growth of Rhizobium Cells

    PubMed Central

    Singh, Ashok Kumar; Singh, Gauri; Gautam, Digvijay; Bedi, Manjinder Kaur

    2013-01-01

    In this study dairy sludge was evaluated as an alternative cultivation medium for Rhizobium. Growth of bacterial strains at different concentrations of Dairy sludge was monitored. Maximum growth of all strains was observed at 60% Dairy sludge concentration. At 60% optical density (OD) values are 0.804 for Rhizobium trifolii (MTCC905), 0.825 for Rhizobium trifolii (MTCC906), and 0.793 for Rhizobium meliloti (MTCC100). Growth pattern of strains was observed at 60% Dairy sludge along with different synthetic media (tryptone yeast, Rhizobium minimal medium and yeast extract mannitol). Growth in 60% Dairy sludge was found to be superior to standard media used for Rhizobium. Media were optimized using 60% dairy sludge along with different concentrations of yeast extract (1–7 g/L) and mannitol (7–13 g/L) in terms of optical density at different time intervals, that is, 24, 48 and 72 hours. Maximum growth was observed in 6 g/L of yeast extract and 12 g/L of mannitol at 48-hour incubation period in all strains. The important environmental parameters such as pH were optimized using 60% dairy sludge, 60% dairy sludge +6 g/L yeast extract, and 60% dairy sludge +12 g/L mannitol. The maximum growth of all strains was found at pH 7.0. The present study recommends the use of 60% dairy sludge as a suitable growth medum for inoculant production. PMID:24089690

  9. Detection of Bacteroides fragilis Enterotoxin Gene by PCR

    PubMed Central

    Shetab, Razeq; Cohen, Stuart H.; Prindiville, Thomas; Tang, Yajarayma J.; Cantrell, Mary; Rahmani, Darush; Silva, Joseph

    1998-01-01

    Bacteroides fragilis constitutes about 1% of the bacterial flora in intestines of normal humans. Enterotoxigenic strains of B. fragilis have been associated with diarrheal diseases in humans and animals. The enterotoxin produced by these isolates induces fluid changes in ligated intestinal loops and an in vitro cytotoxic response in HT-29 cells. We developed a nested PCR to detect the enterotoxin gene of B. fragilis in stool specimens. After DNA extraction, a 367-bp fragment was amplified with two outer primers. The amplicon from this reaction was subjected to a second round of amplification with a set of internal primers. With these inner primers, a 290-bp DNA fragment was obtained which was confirmed as part of the B. fragilis enterotoxin gene by Southern blotting with a nonradioactive internal probe and a chemiluminescence system. By this approach, B. fragilis enterotoxin gene sequences were detected in eight known enterotoxigenic human isolates and nine enterotoxigenic horse isolates. No amplification products were obtained from DNA extracted from 28 nonenterotoxigenic B. fragilis isolates or B. distasonis, B. thetaiotaomicron, B. uniformis, B. ovatus, Escherichia coli, or Clostridium difficile. The sensitivity of this assay allowed us to detect as little as 1 pg of enterotoxin DNA sequences or 100 to 1,000 cells of enterotoxigenic B. fragilis/g of stool. Enterotoxin production of all isolates was confirmed in vitro in HT-29 cells. A 100% correlation was obtained between enterotoxin detection by cytotoxin assay and the nested PCR assay. This rapid and sensitive assay can be used to identify enterotoxigenic B. fragilis and may be used clinically to determine the role of B. fragilis in diarrheal diseases. PMID:9620408

  10. Rhizobium japonicum USDA 191 has two nodD genes that differ in primary structure and function.

    PubMed

    Appelbaum, E R; Thompson, D V; Idler, K; Chartrain, N

    1988-01-01

    Several Rhizobium genes (designated nod genes) are involved in early steps in nodule formation. Here we present the results of DNA sequence and functional analysis of two nodD genes from the symbiotic plasmid of USDA 191, a fast-growing strain that forms nitrogen-fixing nodules on soybeans. Both genes encoded full-length nodD-related polypeptides, which were 69% homologous to each other. One of these genes, nodD1, complemented a Rhizobium trifolii nodD::Tn5 mutant for clover nodulation; the other gene, nodD2, did not. The nodD1 coding region was preceded by a conserved DNA sequence previously noted in other rhizobia, but no such sequence was found in front of nodD2. Plants inoculated with a nodD1 insertion mutant appeared to be nitrogen starved and had a greatly reduced nodule number. Plants inoculated with a nodD2 mutant had a partially nitrogen-starved appearance and normal nodule number, were slightly delayed in nodule formation, and formed nodules that contained reduced levels of nodulin-35 and had fewer bacteroids per infected plant cell. Thus, both of these genes are involved in symbiosis. USDA 191 carrying extra copies of nodD2 on a plasmid vector had an altered colony morphology that suggested inhibition of exopolysaccharide synthesis. The predicted gene products of nodD1 and nodD2 both showed homology to LysR, an E. coli regulatory protein. We conclude that nodD1 probably has the same function as nodD in temperate rhizobia, namely, activation of nodABC transcription in the presence of plant signals. nodD2 may be involved in regulation of exopolysaccharide synthetic genes. PMID:2826389

  11. Rhizobium leguminosarum bv. viciae 3841 Adapts to 2,4-Dichlorophenoxyacetic Acid with “Auxin-Like” Morphological Changes, Cell Envelope Remodeling and Upregulation of Central Metabolic Pathways

    PubMed Central

    Bhat, Supriya V.; Booth, Sean C.; McGrath, Seamus G. K.; Dahms, Tanya E. S.

    2015-01-01

    There is a growing need to characterize the effects of environmental stressors at the molecular level on model organisms with the ever increasing number and variety of anthropogenic chemical pollutants. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), as one of the most widely applied pesticides in the world, is one such example. This herbicide is known to have non-targeted undesirable effects on humans, animals and soil microbes, but specific molecular targets at sublethal levels are unknown. In this study, we have used Rhizobium leguminosarum bv. viciae 3841 (Rlv) as a nitrogen fixing, beneficial model soil organism to characterize the effects of 2,4-D. Using metabolomics and advanced microscopy we determined specific target pathways in the Rlv metabolic network and consequent changes to its phenotype, surface ultrastructure, and physical properties during sublethal 2,4-D exposure. Auxin and 2,4-D, its structural analogue, showed common morphological changes in vitro which were similar to bacteroids isolated from plant nodules, implying that these changes are related to bacteroid differentiation required for nitrogen fixation. Rlv showed remarkable adaptation capabilities in response to the herbicide, with changes to integral pathways of cellular metabolism and the potential to assimilate 2,4-D with consequent changes to its physical and structural properties. This study identifies biomarkers of 2,4-D in Rlv and offers valuable insights into the mode-of-action of 2,4-D in soil bacteria. PMID:25919284

  12. Average nucleotide identity of genome sequences supports the description of Rhizobium lentis sp. nov., Rhizobium bangladeshense sp. nov. and Rhizobium binae sp. nov. from lentil (Lens culinaris) nodules.

    PubMed

    Rashid, M Harun-or; Young, J Peter W; Everall, Isobel; Clercx, Pia; Willems, Anne; Santhosh Braun, Markus; Wink, Michael

    2015-09-01

    Rhizobial strains isolated from effective root nodules of field-grown lentil (Lens culinaris) from different parts of Bangladesh were previously analysed using sequences of the 16S rRNA gene, three housekeeping genes (recA, atpD and glnII) and three nodulation genes (nodA, nodC and nodD), DNA fingerprinting and phenotypic characterization. Analysis of housekeeping gene sequences and DNA fingerprints indicated that the strains belonged to three novel clades in the genus Rhizobium. In present study, a representative strain from each clade was further characterized by determination of cellular fatty acid compositions, carbon substrate utilization patterns and DNA-DNA hybridization and average nucleotide identity (ANI) analyses from whole-genome sequences. DNA-DNA hybridization showed 50-62% relatedness to their closest relatives (the type strains of Rhizobium etli and Rhizobium phaseoli) and 50-60% relatedness to each other. These results were further supported by ANI values, based on genome sequencing, which were 87-92% with their close relatives and 88-89% with each other. On the basis of these results, three novel species, Rhizobium lentis sp. nov. (type strain BLR27(T) = LMG 28441(T) = DSM 29286(T)), Rhizobium bangladeshense sp. nov. (type strain BLR175(T) = LMG 28442(T) = DSM 29287(T)) and Rhizobium binae sp. nov. (type strain BLR195(T) = LMG 28443(T) = DSM 29288(T)), are proposed. These species share common nodulation genes (nodA, nodC and nodD) that are similar to those of the symbiovar viciae. PMID:26060217

  13. Rhizobium helianthi sp. nov., isolated from the rhizosphere of sunflower.

    PubMed

    Wei, Xuexin; Yan, Shouwei; Li, Dai; Pang, Huancheng; Li, Yuyi; Zhang, Jianli

    2015-12-01

    A Gram-stain-negative, non-spore-forming, rod-shaped and aerobic bacterium, designated Xi19T, was isolated from a soil sample collected from the rhizosphere of sunflower (Helianthus annuus) in Wuyuan county of Inner Mongolia, China and was characterized taxonomically by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel isolate was related to species of the genus Rhizobium, sharing the greatest 16S rRNA gene sequence similarity with Rhizobium rhizoryzae J3-AN59T (98.4 %), followed by Rhizobium pseudoryzae J3-A127T (97.4 %). There were low similarities ( < 91 %) between the atpD, recA and glnII gene sequences of the novel strain and those of members of the genus Rhizobium. DNA-DNA hybridization values between strain Xi19T and the most related strain Rhizobium rhizoryzae J3-AN59T were low. The major cellular fatty acids of strain Xi19T were C16 : 0, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C19 : 0 cyclo ω8c. Q-10 was identified as the predominant ubiquinone and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The DNA G+C content of strain Xi19T was 60.2 mol%. On the basis of physiological and biochemical characteristics, coupled with genotypic data obtained in this work, strain Xi19T represents a novel species of the genus Rhizobium, for which the name Rhizobium helianthi is proposed. The type strain is Xi19T ( = CGMCC 1.12192T = KCTC 23879T). PMID:26364048

  14. Specificity of a Bacteroides thetaiotaomicron marker for human feces

    USGS Publications Warehouse

    Carson, C.A.; Christiansen, J.M.; Yampara-Iquise, H.; Benson, V.W.; Baffaut, C.; Davis, J.V.; Broz, R.R.; Kurtz, W.B.; Rogers, W.M.; Fales, W.H.

    2005-01-01

    A bacterial primer set, known to produce a 542-bp amplicon specific for Bacteroides thetaiotaomicron, generated this product in PCR with 1 ng of extracted DNA from 92% of 25 human fecal samples, 100% of 20 sewage samples, and 16% of 31 dog fecal samples. The marker was not detected in 1 ng of fecal DNA from 61 cows, 35 horses, 44 pigs, 24 chickens, 29 turkeys, and 17 geese. Copyright ?? 2005, American Society for Microbiology. All Rights Reserved.

  15. Tn4351 transposes in Bacteroides spp. and mediates the integration of plasmid R751 into the Bacteroides chromosome

    SciTech Connect

    Shoemaker, N.B.; Getty, C.; Gardner, J.F.; Salyers, A.A.

    1986-03-01

    The gene for resistance to erythromycin and clindamycin, which is carried on the conjugative Bacteroides plasmid, pBF4, has been shown previously to be part of an element (Tn4351) that transposes in Escherichia coli. The authors have now introduced Tn4351 into Bacteroides uniformis 0061 on the following two suicide vectors: (i) the broad-host-range IncP plasmid R751 (R751::Tn4351) and (ii) pSS-2, a chimeric plasmid which contains 33 kilobases of pBF4 (including Tn4351) cloned into the IncQ plasmid RSF1010 and which is mobilized by R751. When E. coli HB101, carrying either R751::Tn4351 or R751 and pSS-2, was mated with B. uniformis under aerobic conditions, Em/sup r/ transconjugants were detected at a frequency of 10 /sup -6/ to 10/sup -5/ (R751::Tn4351) or 10/sup -8/ to 10/sup -6/ (R751 and pSS-2). In matings involving pSS-2, all Em/sup r/ transconjugants contained simple insertions of Tn4351 in the chromosome, whereas in matings involving R751::Tn4351, about half of the Em/sup r/ transconjugants had R751 cointegrated with Tn4351 in the chromosome. Of the Em/sup r/ transconjugants, 13% were auxotrophs. Bacteroides spp. which had R751 cointegrated with Tn4351 in the chromosome did not transfer R751 or Tn4351 to E. coli HB101 or to isogenic B. uniformis, nor did the integrated R751 mobilize pE5-2, an E. coli-Bacteroides shuttle vector that contains a transfer origin that is recognized by R751.

  16. Nodules are induced on alfalfa roots by Agrobacterium tumefaciens and Rhizobium trifolii containing small segments of the Rhizobium meliloti nodulation region

    SciTech Connect

    Hirsch, A.M.; Drake, D.; Jacobs, T.W.; Long, S.R.

    1985-01-01

    Regions of the Rhizobium meliloti nodulation genes from the symbiotic plasmid were transferred to Agrobacterium tumefaciens and Rhizobium trifolii by conjugation. The A. tumefaciens and R. trifolii trans-conjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency. These were judged to be genuine nodules on the basis of cytological and developmental criteria. Like genuine alfalfa nodules, the nodules were initiated from divisions of the inner root cortical cells. They developed a distally positioned meristem and several peripheral vascular bundles. An endodermis separated the inner tissues of the nodule from the surrounding cortex. No infection threads were found to penetrate either root hairs or the nodule cells. Bacteria were found only in intercellular spaces. Thus, alfalfa nodules induced by A. tumefaciens and R. trifolii transconjugants carrying small nodulation clones of R. meliloti were completely devoid of intracellular bacteria. When these strains were inoculated onto white clover roots, small nodule-like protrusions developed that, when examined cytologically, were found to more closely resemble roots than nodules. Although the meristem was broadened and lacked a root cap, the protrusions had a central vascular bundle and other rootlike features. The results suggest that morphogenesis of alfalfa root nodules can be uncoupled from infection thread formation. The genes encoded in the 8.7-kilobase nodulation fragment are sufficient in A. tumefaciens or R. trifolii backgrounds for nodule morphogenesis.

  17. Survival of Rhizobium inoculum in hydroseeding slurries

    SciTech Connect

    Brown, M.B.; Wolf, D.D.; Morse, R.D.; Neal, J.L.

    1982-12-01

    Disturbed lands such as surface mined areas generally require fertilizer, lime, mulch, and seed for revegetation. Hydroseeding is the most widely used seeding method for mountainous terrain. Where legumes are included in the mixture, Rhizobium inoculum is recommended since disturbed areas are likely to lack indigenous rhizobia. The pH and viability of rhizobia cells in hydroseeder mix slurries were determined in order to establish recommendations for hydroseeding conditions. Of the fertilizer components commonly used for hydroseeding only those containing phosphorus influenced slurry pH. Varying concentrations of triple superphosphate (TSP) and diammonium phosphate (DAP) resulted in hydroseeder mixture pH values ranging from 2.9 to 7.7, respectively. Significant loss of viability of rhizobia occurred at pH values of less than 6.0. In practice, a hydroseeding slurry should contain enough DAP in the fertilizer blend to have a pH of 6.0 or greater which is equivalent to a ratio of DAP to TSP of 4 to 6. Thus, at least 40 of each 100 kg of phosphate should be supplied by DAP. Pulverized agriculture lime did not correct slurry acidity; however, hydrated lime (calcium hydroxide) if added in sufficient amounts could be used to increase the pH to a level that does not significantly alter the viability of the rhizobia.

  18. Characterisation of SalRAB a Salicylic Acid Inducible Positively Regulated Efflux System of Rhizobium leguminosarum bv viciae 3841

    PubMed Central

    Tett, Adrian J.; Karunakaran, Ramakrishnan; Poole, Philip S.

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants. PMID:25133394

  19. Metabolic Reconstruction and Modeling of Nitrogen Fixation in Rhizobium etli

    PubMed Central

    Resendis-Antonio, Osbaldo; Reed, Jennifer L; Encarnación, Sergio; Collado-Vides, Julio; Palsson, Bernhard Ø

    2007-01-01

    Rhizobiaceas are bacteria that fix nitrogen during symbiosis with plants. This symbiotic relationship is crucial for the nitrogen cycle, and understanding symbiotic mechanisms is a scientific challenge with direct applications in agronomy and plant development. Rhizobium etli is a bacteria which provides legumes with ammonia (among other chemical compounds), thereby stimulating plant growth. A genome-scale approach, integrating the biochemical information available for R. etli, constitutes an important step toward understanding the symbiotic relationship and its possible improvement. In this work we present a genome-scale metabolic reconstruction (iOR363) for R. etli CFN42, which includes 387 metabolic and transport reactions across 26 metabolic pathways. This model was used to analyze the physiological capabilities of R. etli during stages of nitrogen fixation. To study the physiological capacities in silico, an objective function was formulated to simulate symbiotic nitrogen fixation. Flux balance analysis (FBA) was performed, and the predicted active metabolic pathways agreed qualitatively with experimental observations. In addition, predictions for the effects of gene deletions during nitrogen fixation in Rhizobia in silico also agreed with reported experimental data. Overall, we present some evidence supporting that FBA of the reconstructed metabolic network for R. etli provides results that are in agreement with physiological observations. Thus, as for other organisms, the reconstructed genome-scale metabolic network provides an important framework which allows us to compare model predictions with experimental measurements and eventually generate hypotheses on ways to improve nitrogen fixation. PMID:17922569

  20. Rhizobium petrolearium sp. nov., isolated from oil-contaminated soil.

    PubMed

    Zhang, Xiaoxia; Li, Baoming; Wang, Haisheng; Sui, Xinhua; Ma, Xiaotong; Hong, Qing; Jiang, Ruibo

    2012-08-01

    Two Gram-negative, aerobic, rod-shaped bacteria, designated strains SL-1(T) and F11, which had the ability to decompose polycyclic aromatic hydrocarbons (PAHs), were isolated from soil samples contaminated by oil. The cells were motile by polar or lateral flagella. According to comparison of 16S rRNA gene sequences, strains SL-1(T) and F11 were identical and showed the greatest degree of similarity (96.8%) to both Rhizobium oryzae Alt505(T) and Rhizobium mesosinicum CCBAU 25010(T); however, only Rhizobium oryzae with SL-1(T) and F11 formed a separate clade. There were low similarities (<90%) between the atpD and recA sequences of the two strains and those of the genus of Rhizobium. The bacteria grew at temperatures of 10-40 °C with an optimum of 30 °C. The pH range for growth was 6.0-10.0 and optimum pH was 7.0-8.0. Growth occurred at NaCl concentrations up to 3.0% (w/v). They were catalase- and oxidase-positive. The main cellular fatty acids were summed feature 8 (18:1ω7c and/or 18:1ω6c) and 16:0. The DNA G+C content was 62.2 mol%. Strain SL-1(T) showed 29 and 0% DNA-DNA relatedness, respectively, with the most related strains R. oryzae Alt505(T) and R. mesosinicum CCBAU 25010(T) according to phylogenic analysis of the 16S rRNA gene. According to physiological and biochemical characteristics and genotypic data obtained in this work, the bacteria represent a novel species of the genus Rhizobium, and the name Rhizobium petrolearium is proposed. The type strain is SL-1(T) ( = ACCC 11238(T) = KCTC 23288(T)) and it could nodulate Medicago sativa in nodulation tests. PMID:21984664

  1. Rhizobium sophorae sp. nov. and Rhizobium sophoriradicis sp. nov., nitrogen-fixing rhizobial symbionts of the medicinal legume Sophora flavescens.

    PubMed

    Jiao, Yin Shan; Yan, Hui; Ji, Zhao Jun; Liu, Yuan Hui; Sui, Xin Hua; Wang, En Tao; Guo, Bao Lin; Chen, Wen Xin; Chen, Wen Feng

    2015-02-01

    Five bacterial strains representing 45 isolates originated from root nodules of the medicinal legume Sophora flavescens were defined as two novel groups in the genus Rhizobium based on their phylogenetic relationships estimated from 16S rRNA genes and the housekeeping genes recA, glnII and atpD. These groups were distantly related to Rhizobium leguminosarum USDA 2370(T) (95.6 % similarity for group I) and Rhizobium phaseoli ATCC 14482(T) (93.4 % similarity for group II) in multilocus sequence analysis. In DNA-DNA hybridization experiments, the reference strains CCBAU 03386(T) (group I) and CCBAU 03470(T) (group II) showed levels of relatedness of 17.9-57.8 and 11.0-42.9 %, respectively, with the type strains of related species. Both strains CCBAU 03386(T) and CCBAU 03470(T) contained ubiquinone 10 (Q-10) as the major respiratory quinone and possessed 16 : 0, 18 : 0, 19 : 0 cyclo ω8c, summed feature 8 and summed feature 2 as major fatty acids, but did not contain 20 : 3 ω6,8,12c. Phenotypic features distinguishing both groups from all closely related species of the genus Rhizobium were found. Therefore, two novel species, Rhizobium sophorae sp. nov. for group I (type strain CCBAU 03386(T) = E5(T) = LMG 27901(T) = HAMBI 3615(T)) and Rhizobium sophoriradicis sp. nov. for group II (type strain CCBAU 03470(T) = C-5-1(T) = LMG 27898(T) = HAMBI 3510(T)), are proposed. Both groups were able to nodulate Phaseolus vulgaris and their hosts of origin (Sophora flavescens) effectively and their nodulation gene nodC was phylogenetically located in the symbiovar phaseoli. PMID:25385989

  2. Enterotoxigenic and nontoxigenic Bacteroides fragilis strains isolated in Brazil.

    PubMed

    Miranda, Karla R; Dias, Mariana F; Guimarães, Priscilla L S; Boente, Renata F; Pauer, Heidi; Ramos, Priscila Z; Falcão, Laís S; Ferreira, Eliane de O; Balassiano, Ilana T; Ferreira, Livia Q; Santos-Filho, Joaquim dos; Paula, Geraldo R de; Antunes, Eduardo N F; Avelar, Katia E S; Domingues, Regina M C P

    2008-11-01

    The presence of enterotoxigenic Bacteroides fragilis and nontoxigenic B. fragilis (NTBF) among 109 strains isolated from 1980-2008 in Brazil were investigated by PCR. One strain, representing 0.9% of the total analyzed strains, harbored the bft gene which was identified as bft-1 isoform based on PCR-RFLP and sequencing. Forty-nine strains (44.9%) exhibited the NTBF pattern III which possesses the flanking region required for pathogenicity island acquisition in which the bft gene is codified. These data reinforce the potential of B. fragilis as an emerging enteropathogen in our country. PMID:19057827

  3. Characteristics of Bacteroides isolates from the cecum of conventional mice.

    PubMed Central

    Tannock, G W

    1977-01-01

    Bacteroides isolates from the cecum of conventional mice were characterized and grouped according to their ability to ferment or hydrolyze carbohydrates and other compounds believed to be present in the intestinal ecosystem. The isolates were divided into 11 groups on the basis of the fermentation of glucose, cellobiose, gum arabic and xylan (hemicelluloses), N-acetylglucosamine, and dextrin; the hydrolysis of starch and casein (proteolysis); and the production of indole. Stock cultures of B. fragilis, B. distasonis, B. ovatus, B. vulgatus, and B. ruminicola were characterized in the same way. The strains isolated most frequently from the mouse cecum resembled B. fragilis (except that arabinose was fermented) and B. thetaiotaomicron. PMID:869524

  4. Surface location of a Bacteroides gingivalis glycylprolyl protease.

    PubMed Central

    Grenier, D; McBride, B C

    1989-01-01

    Various immunological methods were used to localize a glycylprolyl protease previously isolated from Bacteroides gingivalis ATCC 33277. The results obtained by enzyme-linked immunosorbent assay, indirect immunofluorescence staining, and indirect immunogold labeling suggest that the glycylprolyl protease is present on the surface of the cell outer membrane and is specific to B. gingivalis strains. The enzyme was removed from the cell envelope by treatment of the whole cells with sodium dodecyl sulfate, Triton X-100, sodium deoxycholate, and proteinase K. Images PMID:2807524

  5. Transposon Tn5 specifies streptomycin resistance in Rhizobium spp.

    PubMed Central

    Selvaraj, G; Iyer, V N

    1984-01-01

    Transposon Tn5 conferred streptomycin resistance on different strains of Rhizobium meliloti, Rhizobium leguminosarum, and Rhizobium trifolii but not on Escherichia coli. A gene (str) specifying this phenotype has been identified and localized on the physical and genetic map of Tn5. It is transcribed from the promoter of neo, the gene that encodes neomycin phosphotransferase. The str gene is downstream from neo in a single transcriptional unit, as revealed by molecular cloning of different segments of Tn5 and by cloning of the neo-str region of Tn5 downstream from a lac promoter. Fusion of the SalI-generated rightward segment of Tn5 (devoid of neo) to a part of a tetracycline resistance gene, tet, in a plasmid or downstream from a lac promoter in a plasmid resulted in significant levels of streptomycin resistance in an R. meliloti host, suggesting that the str gene product can function independent of neomycin phosphotransferase. A natural isolate of R. meliloti that does not express Tn5-associated streptomycin resistance has been identified. We have used the str of Tn5 as a genetic marker in Rhizobium spp. PMID:6327612

  6. A rhizobium selenitireducens protein showing selenite reductase activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biobarriers remove, via precipitation, the metalloid selenite (SeO3–2) from groundwater; a process that involves the biological reduction of soluble SeO3–2 to insoluble elemental red selenium (Se0). The enzymes associated with this reduction process are poorly understood. In Rhizobium selenitiredu...

  7. Diversity of Rhizobium leguminosarum from pea fields in Washington State

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizobia-mediated biological nitrogen (N) fixation in legumes contributes to yield potential in these crops and also provides residual fertilizer to subsequent cereals. Our objectives were to collect isolates of Rhizobium leguminosarum from several pea fields in Washington, examine genetic diversity...

  8. Infection and nodulation of clover by nonmotile Rhizobium trifolii

    SciTech Connect

    Napoli, C.; Albersheim, P.

    1980-02-01

    Nonmotile mutants of Rhizobium trifolii were isolated to determine whether bacterial motility is required for the infection and nodulation of clover. The nonmotile mutants were screened for their ability to infect and nodulate clover seedlings in Fahraeus glass slide assemblies, plastic growth pouches, and vermiculite-sand-filled clay pots. In each system, the nonmotile mutants were able to infect and nodulate clover.

  9. Rhizobium paknamense sp. nov., isolated from lesser duckweeds (Lemna aequinoctialis).

    PubMed

    Kittiwongwattana, Chokchai; Thawai, Chitti

    2013-10-01

    A Gram-stain-negative, rod-shaped bacterium was isolated and designated strain L6-8(T) during a study of endophytic bacterial communities in lesser duckweed (Lemna aequinoctialis). Cells of strain L6-8(T) were motile with peritrichous flagella. The analysis of the nearly complete 16S rRNA gene sequence indicated that strain L6-8(T) was phylogenetically related to species of the genus Rhizobium. Its closest relatives were Rhizobium borbori DN316(T) (97.6 %), Rhizobium oryzae Alt 505(T) (97.3 %) and Rhizobium pseudoryzae J3-A127(T) (97.0 %). The sequence similarity analysis of housekeeping genes recA, glnII, atpD and gyrB showed low levels of sequence similarity (<91.5 %) between strain L6-8(T) and other species of the genus Rhizobium with validly published names. The pH range for growth was 4.0-9.0 (optimum 6.0-7.0), and the temperature range for growth was 20-45 °C (optimum 30 °C). Strain L6-8(T) tolerated NaCl up to 2 % (w/v) (optimum 1 % NaCl). The predominant components of cellular fatty acids were C19 : 0 cyclo ω8c (31.32 %), summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 25.39 %) and C16 : 0 (12.03 %). The DNA G+C content of strain L6-8(T) was 60.4 mol% (Tm). nodC and nifH were not amplified in strain L6-8(T). DNA-DNA relatedness between strain L6-8(T) and R. borbori DN316(T), R. oryzae Alt505(T) and R. pseudoryzae J3-A127(T) was between 11.2 and 18.3 %. Based on the sequence similarity analyses, phenotypic, biochemical and physiological characteristics and DNA-DNA hybridization, strain L6-8(T) could be readily distinguished from its closest relatives and represents a novel species of the genus Rhizobium, for which the name Rhizobium paknamense sp. nov. is proposed. The type strain is L6-8(T) ( = NBRC 109338(T) = BCC 55142(T)). PMID:23687054

  10. Protein phosphorylation in Bradyrhizobium japonicum bacteroids and cultures.

    PubMed Central

    Karr, D B; Emerich, D W

    1989-01-01

    Protein phosphorylation was demonstrated in Bradyrhizobium japonicum bacteroids in vivo and in cultures in vivo and in vitro. Comparison of in vivo-labeled phosphoproteins of bacteroids and of cultured cells showed differences in both the pattern and intensity of labeling. In cultured cells, comparison of the labeling patterns and intensities of in vivo- and in vitro-labeled phosphoproteins showed a number of similarities; however, several phosphoproteins were found only after one of the two labeling conditions. The labeling intensity was time dependent in both in vivo and in vitro assays and was dependent on the presence of magnesium in in vitro assays. Differences in the rates of phosphorylation and dephosphorylation were noted for a number of proteins. The level of incorporation of 32P into protein was only 2% or less of the total phosphate accumulated during the in vivo labeling period. Several isolation and sample preparation procedures resulted in differences in labeling patterns. Phosphatase inhibitors and several potential metabolic effectors had negligible effects on the phosphorylation pattern. There were no significant changes in the phosphorylation patterns of cells cultured on mannitol, acetate, and succinate, although the intensity of the labeling did vary with the carbon source. Images PMID:2498290

  11. Protein phosphorylation in Bradyrhizobium japonicum bacteroids and cultures

    SciTech Connect

    Karr, D.B.; Emerich, D.W. )

    1989-06-01

    Protein phosphorylation was demonstrated in Bradyrhizobium japonicum bacteroids in vivo and in cultures in vivo and in vitro. Comparison of in vivo-labeled phosphoproteins of bacteroids and of cultured cells showed differences in both the pattern and intensity of labeling. In cultured cells, comparison of the labeling patterns and intensities of in vivo- and in vitro-labeled phosphoproteins showed a number of similarities; however, several phosphoproteins were found only after one of the two labeling conditions. The labeling intensity was time dependent in both in vivo and in vitro assays and was dependent on the presence of magnesium in in vitro assays. Differences in the rates of phosphorylation and dephosphorylation were noted for a number of proteins. The level of incorporation of {sup 32}P into protein was only 2% or less of the total phosphate accumulated during the in vivo labeling period. Several isolation and sample preparation procedures resulted in differences in labeling patterns. Phosphatase inhibitors and several potential metabolic effectors had negligible effects on the phosphorylation pattern. There were no significant changes in the phosphorylation patterns of cells cultured on mannitol, acetate, and succinate, although the intensity of the labeling did vary with the carbon source.

  12. Determinants of nodulation competitiveness in Rhizobium etli. Final report for period September 30, 1996--September 29, 1999

    SciTech Connect

    Handelsman, Jo

    2000-01-04

    Nitrogen is a major limiting nutrient in crop production. Chemical fertilizers, which are used extensively to meet crop nitrogen requirements, contribute to the high energy inputs of modern agriculture and cause human health and environmental problems. Legumes and their bacterial associates have long been used in crop rotations to replenish soil nitrogen, but effective and reliable biological nitrogen fixation for beans is prevented by the lack of nodulation competitiveness of many Rhizobium strains used as inoculants. The result is that the inoculant strains will not occupy the host's nodules and no benefit will be derived from inoculation. Many indigenous soil strains of Rhizobium etli bv. phaseoli, the symbiont of bean, nodulate but fix little or no nitrogen, and therefore the nodulation competitiveness problem is significant for achieving maximum nitrogen benefit from bean crops. This project was directed toward developing an understanding of the basis of nodulation competitiveness.

  13. Survival of Rhizobium in Acid Soils

    PubMed Central

    Lowendorf, Henry S.; Baya, Ana Maria; Alexander, Martin

    1981-01-01

    A Rhizobium strain nodulating cowpeas did not decline in abundance after it was added to sterile soils at pH 6.9 and 4.4, and the numbers fell slowly in nonsterile soils at pH 5.5 and 4.1. A strain of R. phaseoli grew when added to sterile soils at pH 6.7 and 6.9; it maintained large, stable populations in soils of pH 4.4, 5.5, and 6.0, but the numbers fell markedly and then reached a stable population size in sterile soils at pH 4.3 and 4.4. The abundance of R. phaseoli added to nonsterile soils with pH values of 4.3 to 6.7 decreased similarly with time regardless of soil acidity, and the final numbers were less than in the comparable sterile soils. The minimum pH values for the growth of strains of R. meliloti in liquid media ranged from 5.3 to 5.9. Two R. meliloti strains, which differed in acid tolerance for growth in culture, did not differ in numbers or decline when added to sterile soils at pH 4.8, 5.2, and 6.3. The population size of these two strains was reduced after they were introduced into nonsterile soils at pH 4.8, 5.4, and 6.4, and the number of survivors was related to the soil pH. The R. meliloti strain that was more acid sensitive in culture declined more readily in sterile soil at pH 4.6 than did the less sensitive strain, and only the former strain was eliminated from nonsterile soil at pH 4.8; however, the less sensitive strain also survived better in limed soil. The cell density of the two R. meliloti strains was increased in pH 6.4 soil in the presence of growing alfalfa. The decline and elimination of the tolerant, but not the sensitive, strain was delayed in soil at pH 4.6 by roots of growing alfalfa. PMID:16345909

  14. Protection of sheep against experimental footrot by vaccination with pili purified from Bacteroides nodosus.

    PubMed

    Every, D; Skerman, T M

    1982-10-01

    Merino sheep vaccinated with either whole Bacteroides nodosus organisms, a crude surface antigen preparation or highly purified pili (>99% homogeneity) in oil adjuvant, developed significant resistance to artificial footrot infection when compared with unvaccinated control sheep inoculated with saline-in-oil emulsion (Freund;s incomplete adjuvant) alone. The pili-vaccinated sheep generally had higher K-agglutinating antibody titres than sheep vaccinated with whole B. nodosus. These results confirmed the role of B. nodosus pilus protein both as a protective antigen and the K-agglutinogen. Vaccines prepared with Freund;s incomplete adjuvant containing either purified pili, crude pili or B. nodosus whole cells did not produce significantly different injection-site reactions. PMID:16030827

  15. Rhizobium meliloti exopolysaccharide mutants elicit feedback regulation of nodule formation in alfalfa

    SciTech Connect

    Caetano-Anolles, G.; Lagares, A.; Bauer, W.D. )

    1990-02-01

    Nodule formation by wild-type Rhizobium meliloti is strongly suppressed in younger parts of alfalfa (Medicago sativum L.) root systems as a feedback response to development of the first nodules. Mutants of R. meliloti deficient in exopolysaccharide synthesis can induce the formation of organized nodular structures (pseudonodules) on alfalfa roots but are defective in their ability to invade and multiply within host tissues. The formation of empty pseudonodules by exo mutants was found to elicit a feedback suppression of nodule formation similar to that elicited by the wild-type bacteria. Inoculation of an exo mutant onto one side of a split-root system 24 hours before inoculation of the second side with wild-type cells suppressed wild-type nodule formation on the second side in proportion to the extent of pseudonodule formation by the exo mutants. The formation of pseudonodules is thus sufficient to elicit systemic feedback control of nodulation in the host root system: infection thread development and internal proliferation of the bacteria are not required for elicitation of feedback. Pseudonodule formation by the exo mutants was found to be strongly suppressed in split-root systems by prior inoculation on the opposite side with the wild type. Thus, feedback control elicited by the wild-type inhibits Rhizobium-induced redifferentiation of host root cells.

  16. 5S ribosomal ribonucleic acid sequences in Bacteroides and Fusobacterium: evolutionary relationships within these genera and among eubacteria in general

    NASA Technical Reports Server (NTRS)

    Van den Eynde, H.; De Baere, R.; Shah, H. N.; Gharbia, S. E.; Fox, G. E.; Michalik, J.; Van de Peer, Y.; De Wachter, R.

    1989-01-01

    The 5S ribosomal ribonucleic acid (rRNA) sequences were determined for Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides capillosus, Bacteroides veroralis, Porphyromonas gingivalis, Anaerorhabdus furcosus, Fusobacterium nucleatum, Fusobacterium mortiferum, and Fusobacterium varium. A dendrogram constructed by a clustering algorithm from these sequences, which were aligned with all other hitherto known eubacterial 5S rRNA sequences, showed differences as well as similarities with respect to results derived from 16S rRNA analyses. In the 5S rRNA dendrogram, Bacteroides clustered together with Cytophaga and Fusobacterium, as in 16S rRNA analyses. Intraphylum relationships deduced from 5S rRNAs suggested that Bacteroides is specifically related to Cytophaga rather than to Fusobacterium, as was suggested by 16S rRNA analyses. Previous taxonomic considerations concerning the genus Bacteroides, based on biochemical and physiological data, were confirmed by the 5S rRNA sequence analysis.

  17. Carbohydrate, Organic Acid, and Amino Acid Composition of Bacteroids and Cytosol from Soybean Nodules 1

    PubMed Central

    Streeter, John G.

    1987-01-01

    Metabolites in Bradyrhizobium japonicum bacteroids and in Glycine max (L.) Merr. cytosol from root nodules were analyzed using an isolation technique which makes it possible to estimate and correct for changes in concentration which may occur during bacteroid isolation. Bacteroid and cytosol extracts were fractionated on ion-exchange columns and were analyzed for carbohydrate composition using gas-liquid chromatography and for organic acid and amino acid composition using high performance liquid chromatography. Analysis of organic acids in plant tissues as the phenacyl derivatives is reported for the first time and this approach revealed the presence of several unknown organic acids in nodules. The time required for separation of bacteroids and cytosol was varied, and significant change in concentration of individual compounds during the separation of the two fractions was estimated by calculating the regression of concentration on time. When a statistically significant slope was found, the true concentration was estimated by extrapolating the regression line to time zero. Of 78 concentration estimates made, there was a statistically significant (5% level) change in concentration during sample preparation for only five metabolites: glucose, sucrose, and succinate in the cytosol and d-pinitol and serine in bacteroids. On a mass basis, the major compounds in bacteroids were (descending order of concentration): myo-inositol, d-chiro-inositol, α,α-trehalose, sucrose, aspartate, glutamate, d-pinitol, arginine, malonate, and glucose. On a proportional basis (concentration in bacteroid as percent of concentration in bacteroid + cytosol fractions), the major compounds were: α-aminoadipate (94), trehalose (66), lysine (58), and arginine (46). The results indicate that metabolite concentrations in bacteroids can be reliably determined. PMID:16665774

  18. Expression of pili from Bacteroides nodosus in Pseudomonas aeruginosa.

    PubMed Central

    Elleman, T C; Hoyne, P A; Stewart, D J; McKern, N M; Peterson, J E

    1986-01-01

    The pili of Bacteroides nodosus, the causative agent of ovine footrot, constitute the major host-protective immunogen against homologous serotypic challenge. The pilin gene from B. nodosus 198 has been cloned and morphologically expressed as extracellular pili in Pseudomonas aeruginosa by using a plasmid-borne, thermoregulated expression system. B. nodosus pilin could not be detected in cultures of P. aeruginosa grown at 32 degrees C, but after induction at 37 degrees C, B. nodosus pili were expressed on the cell surface of P. aeruginosa to the virtual exclusion of the host cell pili. Pili harvested from induced P. aeruginosa cultures were used to immunize sheep against footrot. The serum agglutinating antibody titers of vaccinated sheep were comparable to those of sheep receiving pili from B. nodosus. Subsequent challenge of the sheep with B. nodosus 198 indicated that the recombinant- DNA-derived pili vaccine and the B. nodosus pili vaccine provided similar levels of protection against footrot. Images PMID:2877967

  19. Basis for the competitiveness of rhizobium japonicum in nodulation of soybean. Final progress report

    SciTech Connect

    Bauer, W.D.; Evans, W.R.

    1984-07-30

    These studies were concerned with the determination of the characteristics of the soybean symbiont R. japonicum that are crucial to the inoculum competitiveness of one strain of the bacterium over other strains with respect to nodule formation. Our work has been focused on the initial infection events, such as attachment, which precede the development of a fully functional nodule because it is these primary events which determine the success or failure of a particular rhizobia to initiate infections. Experiments concerned with the attachment of R. japonicum to soybean roots have indicated that both soybean symbiotic and non-symbiotic species of rhizobia attach comparably well to soybean roots. There was no evidence of attachment mediated by soybean lectin, as previously claimed, but evidence was obtained for attachment mediated by pili on the Rhizobium cells. It was also found that the efficiency of infection varied substantially with culture age for certain strains while with other strains the efficiency of infection remained approximately constant during growth. We have utilized these observations to investigate the relationship between the efficiency of infection and competitiveness. An unexpected outcome of these studies was the finding that R. japonicum, and other slow-growing Rhizobium species, maintain both viability and symbiotic infectivity over prolonged periods of storage at ambient temperatures when suspended in water. The simplicity and cost-effectiveness of this storage procedure may provide an alternative method to the current practices employed in inoculum preparation. 2 figures, 3 tables.

  20. Genome sequence of the clover symbiont Rhizobium leguminosarum bv. trifolii strain CC275e.

    PubMed

    Delestre, Clément; Laugraud, Aurélie; Ridgway, Hayley; Ronson, Clive; O'Callaghan, Maureen; Barrett, Brent; Ballard, Ross; Griffiths, Andrew; Young, Sandra; Blond, Celine; Gerard, Emily; Wakelin, Steve

    2015-01-01

    Rhizobium leguminosarum bv. trifolii strain CC275e is a highly effective, N2-fixing microsymbiont of white clover (Trifolium repens L.). The bacterium has been widely used in both Australia and New Zealand as a clover seed inoculant and, as such, has delivered the equivalent of millions of dollars of nitrogen into these pastoral systems. R. leguminosarum strain CC275e is a rod-shaped, motile, Gram-negative, non-spore forming bacterium. The genome was sequenced on an Illumina MiSeq instrument using a 2 × 150 bp paired end library and assembled into 29 scaffolds. The genome size is 7,077,367 nucleotides, with a GC content of 60.9 %. The final, high-quality draft genome contains 6693 protein coding genes, close to 85 % of which were assigned to COG categories. This Whole Genome Shotgun project has been deposited at DDBJ/EMBL/GenBank under the accession JRXL00000000. The sequencing of this genome will enable identification of genetic traits associated with host compatibility and high N2 fixation characteristics in Rhizobium leguminosarum. The sequence will also be useful for development of strain-specific markers to assess factors associated with environmental fitness, competiveness for host nodule occupancy, and survival on legume seeds (New Zealand Ministry of Business, Innovation and Employment program, 'Improving forage legume-rhizobia performance' contract C10X1308 and DairyNZ Ltd.). PMID:26649149

  1. Persistence of Bacteroides ovatus under simulated sunlight irradiation

    PubMed Central

    2014-01-01

    Background Bacteroides ovatus, a member of the genus Bacteroides, is considered for use in molecular-based methods as a general fecal indicator. However, knowledge on its fate and persistence after a fecal contamination event remains limited. In this study, the persistence of B. ovatus was evaluated under simulated sunlight exposure and in conditions similar to freshwater and seawater. By combining propidium monoazide (PMA) treatment and quantitative polymerase chain reaction (qPCR) detection, the decay rates of B. ovatus were determined in the presence and absence of exogenous photosensitizers and in salinity up to 39.5 parts per thousand at 27°C. Results UVB was found to be important for B. ovatus decay, averaging a 4 log10 of decay over 6 h of exposure without the presence of extracellular photosensitizers. The addition of NaNO2, an exogenous sensitizer producing hydroxyl radicals, did not significantly change the decay rate of B. ovatus in both low and high salinity water, while the exogenous sensitizer algae organic matter (AOM) slowed down the decay of B. ovatus in low salinity water. At seawater salinity, the decay rate of B. ovatus was slower than that in low salinity water, except when both NaNO2 and AOM were present. Conclusion The results of laboratory experiments suggest that if B. ovatus is released into either freshwater or seawater environment in the evening, 50% of it may be intact by the next morning; if it is released at noon, only 50% may be intact after a mere 5 min of full spectrum irradiation on a clear day. This study provides a mechanistic understanding to some of the important environmental relevant factors that influenced the inactivation kinetics of B. ovatus in the presence of sunlight irradiation, and would facilitate the use of B. ovatus to indicate the occurrence of fecal contamination. PMID:24993443

  2. Impact of heavy metals on an arctic rhizobium

    SciTech Connect

    Appanna, V.D. )

    1991-03-01

    Bacteria belonging to the genus Rhizobium, when residing in the root nodules of leguminous plants, fix nitrogen and thus contribute very significantly to the global nitrogen and thus contribute very significantly to the global nitrogen budget. Although there is paucity of data concerning the effects of metal pollutants on these agronomically important organisms, their negative impact on the nitrogen fixing ability of these microbes is evident. As rhizobia from root nodules of arctic legumes have been demonstrated to contribute significantly to the ecological balance in this region, the impact of some metals, found in elevated amounts in acidic surroundings on this unique Rhizobium has been assessed. In this paper the ability of the microbe to tolerate abnormal levels of manganese and aluminum is reported and the effectiveness of iron in reversing cadmium toxicity is also discussed.

  3. Regulation of phenolic catabolism in Rhizobium leguminosarum biovar trifolii

    SciTech Connect

    Parke, D. ); Rynne, F.; Glenn, A. )

    1991-09-01

    In members of the family Rhizobiaceae, many phenolic compounds are degraded by the protocatechuate branch of the {beta}-ketoadipate pathway, In this paper the authors describe a novel pattern of induction of protocatechuate (pca) genes in Rhizobium leguminosarum biovar trifolii. Isolation of pca mutant strains revealed that 4-hydroxybenzoate, quinate, and 4-coumarate are degraded via the protocatechuate pathway. At least three inducers govern catabolism of 4-hydroxybenzoate to succinyl coenzyme A and acetyl coenzyme A. The enzyme that catalyzes the initial step is induced by its substrate, whereas the catabolite {beta}-carboxy-cis, cis-muconate induces enzymes for the upper protocatechuate pathway, and {beta}-ketoadipate elicits expression of the enzyme for a subsequent step, {beta}-ketoadipate succinyl-coenzyme A transferase. Elucidation of the induction pattern relied in part on complementation of mutant Rhizobium strains by known subclones of Acinetobacter genes expressed off the lac promoter in a broad-host-range vector.

  4. Rhizobium pongamiae sp. nov. from Root Nodules of Pongamia pinnata

    PubMed Central

    Kesari, Vigya; Ramesh, Aadi Moolam; Rangan, Latha

    2013-01-01

    Pongamia pinnata has an added advantage of N2-fixing ability and tolerance to stress conditions as compared with other biodiesel crops. It harbours “rhizobia” as an endophytic bacterial community on its root nodules. A gram-negative, nonmotile, fast-growing, rod-shaped, bacterial strain VKLR-01T was isolated from root nodules of Pongamia that grew optimal at 28°C, pH 7.0 in presence of 2% NaCl. Isolate VKLR-01 exhibits higher tolerance to the prevailing adverse conditions, for example, salt stress, elevated temperatures and alkalinity. Strain VKLR-01T has the major cellular fatty acid as C18:1  ω7c (65.92%). Strain VKLR-01T was found to be a nitrogen fixer using the acetylene reduction assay and PCR detection of a nifH gene. On the basis of phenotypic, phylogenetic distinctiveness and molecular data (16S rRNA, recA, and atpD gene sequences, G + C content, DNA-DNA hybridization etc.), strain VKLR-01T = (MTCC 10513T = MSCL 1015T) is considered to represent a novel species of the genus Rhizobium for which the name Rhizobium pongamiae sp. nov. is proposed. Rhizobium pongamiae may possess specific traits that can be transferred to other rhizobia through biotechnological tools and can be directly used as inoculants for reclamation of wasteland; hence, they are very important from both economic and environmental prospects. PMID:24078904

  5. Non-contiguous finished genome sequence of Bacteroides coprosuis type strain (PC 139T)

    SciTech Connect

    Land, Miriam L; Held, Brittany; Gronow, Sabine; Abt, Birte; Lucas, Susan; Glavina Del Rio, Tijana; Nolan, Matt; Tice, Hope; Cheng, Jan-Fang; Pitluck, Sam; Liolios, Konstantinos; Pagani, Ioanna; Ivanova, N; Mavromatis, K; Pati, Amrita; Tapia, Roxanne; Han, Cliff; Goodwin, Lynne A.; Chen, Amy; Palaniappan, Krishna; Hauser, Loren John; Brambilla, Evelyne-Marie; Rohde, Manfred; Goker, Markus; Detter, J. Chris; Woyke, Tanja; Bristow, James; Eisen, Jonathan; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Lapidus, Alla L.

    2011-01-01

    Bacteroides coprosuis Whitehead et al. 2005 belongs to the genus Bacteroides, which is a member of the family Bacteroidaceae. Members of the genus Bacteroides in general are known as beneficial protectors of animal guts against pathogenic microorganisms, and as contributors to the degradation of complex molecules such as polysaccharides. B. coprosuis itself was isolated from a manure storage pit of a swine facility, but has not yet been found in an animal host. The species is of interest solely because of its isolated phylogenetic location. The genome of B. coprosuis is already the 5th sequenced type strain genome from the genus Bacteroides. The 2,991,798 bp long genome with its 2,461 protein-coding and 78 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  6. Root Exudates of Various Host Plants of Rhizobium leguminosarum Contain Different Sets of Inducers of Rhizobium Nodulation Genes.

    PubMed

    Zaat, S A; Wijffelman, C A; Mulders, I H; van Brussel, A A; Lugtenberg, B J

    1988-04-01

    Rhizobium promoters involved in the formation of root nodules on leguminous plants are activated by flavonoids in plant root exudate. A series of Rhizobium strains which all contain the inducible Rhizobium leguminosarum nodA promoter fused to the Escherichia coli lacZ gene, and which differ only in the source of the regulatory nodD gene, were recently used to show that the regulatory nodD gene determines which flavonoids are able to activate the nodA promoter (HP Spaink, CA Wijffelman, E Pees, RJH Okker, BJJ Lugtenberg 1987 Nature 328: 337-340). Since these strains therefore are able to discriminate between various flavonoids, they were used to determine whether or not plants that are nodulated by R. leguminosarum produce different inducers. After chromatographic separation of root exudate constituents from Vicia sativa L. subsp. nigra (L.), V. hirsuta (L.) S.F. Gray, Pisum sativum L. cv Rondo, and Trifolium subterraneum L., the fractions were tested with a set of strains containing a nodD gene of R. leguminosarum, R. trifolii, or Rhizobium meliloti, respectively. It appeared that the source of nodD determined whether, and to what extent, the R. leguminosarum nodA promoter was induced. Lack of induction could not be attributed to the presence of inhibitors. Most of the inducers were able to activate the nodA promoter in the presence of one particular nodD gene only. The inducers that were active in the presence of the R. leguminosarum nodD gene were different in each root exudate. PMID:16666070

  7. Rhizobium ipomoeae sp. nov., isolated from a water convolvulus field.

    PubMed

    Sheu, Shih-Yi; Chen, Zih-Han; Young, Chiu-Chung; Chen, Wen-Ming

    2016-04-01

    A bacterial strain, designated shin9-1T, was isolated from a water sample taken from a water convolvulus field in Taiwan and characterized using a polyphasic taxonomical approach. Cells of strain shin9-1T were aerobic, Gram-stain-negative, rod-shaped and surrounded by a thick capsule and formed cream-coloured colonies. Growth occurred at 10-45 °C (optimum, 30 °C), with 0-3.0 % NaCl (optimum, 0.5 %) and at pH 7.0-9.0 (optimum, pH 7.0). Strain shin9-1T did not form nodules on a legume plant, Macroptilium atropurpureum, and the nodulation genes nodA, nodC and the nitrogenase reductase gene nifH were not detected by PCR. Phylogenetic analyses based on 16S rRNA and three housekeeping gene sequences (recA, atpD and rpoB) showed that strain shin9-1T belonged to the genus Rhizobium. Strain shin9-1T had the highest level of 16S rRNA gene sequence similarity with respect to Rhizobium daejeonense L61T (97.6 %). The major fatty acid of strain shin9-1T was C18 : 1ω7c. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, phosphatidylmonomethylethanolamine and several uncharacterized lipids. The DNA G+C content was 58.3 mol%. The DNA-DNA relatedness of strain shin9-1T with respect to recognized species of the genus Rhizobium was less than 70 %. Phenotypic characteristics of the novel strain also differed from those of the most closely related species of the genus Rhizobium. On the basis of the phylogenetic inference and phenotypic data, strain shin9-1T should be classified as a representative of a novel species, for which the name Rhizobium ipomoeae sp. nov. is proposed. The type strain is shin9-1T ( = LMG 27163T = KCTC 32148T). PMID:26739022

  8. Draft Genome Sequence of Rhizobium sp. GHKF11, Isolated from Farmland Soil in Pecan Grove, Texas.

    PubMed

    Iyer, Rupa; Damania, Ashish

    2016-01-01

    Rhizobium sp. GHKF11 is an organophosphate-degrading bacterial strain that was isolated from farmland soil in Pecan Grove, Texas, USA. In addition to a capacity for pesticide degradation, GHKF11 shares conserved traits with other Rhizobium spp., including heavy metal resistance and transport genes that may have significant agricultural biotechnology applications. PMID:27445376

  9. Effects of nano-ZnO on the agronomically relevant Rhizobium-legume symbiosis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of nano-ZnO (nZnO) on Rhizobium-legume symbiosis was studied with garden pea and its compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure of peas to nZnO had no impact on germination, but significantly affected root length. Chronic exposure of plant to nZnO impac...

  10. Draft Genome Sequence of Rhizobium sp. GHKF11, Isolated from Farmland Soil in Pecan Grove, Texas

    PubMed Central

    Damania, Ashish

    2016-01-01

    Rhizobium sp. GHKF11 is an organophosphate-degrading bacterial strain that was isolated from farmland soil in Pecan Grove, Texas, USA. In addition to a capacity for pesticide degradation, GHKF11 shares conserved traits with other Rhizobium spp., including heavy metal resistance and transport genes that may have significant agricultural biotechnology applications. PMID:27445376

  11. Effects of nano-TiO2 on the agronomically-relevant Rhizobium-legume symbiosis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of nano-TiO2 on Rhizobium-legume symbiosis was studied using garden peas and the compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure to nano-TiO2 did not affect the germination of peas grown aseptically, nor did it impact the gross root structure. However, nano-...

  12. Rhizobium selenireducens sp. nov.: A selenite reducing a-Proteobacteria isolated from a bioreactor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A Gram-negative, non-pigmented bacterium designated strain B1 was isolated from a laboratory bioreactor that reduced selenate to elemental red selenium (Se0). 16S rRNA gene sequence alignment identified the isolate as a Rhizobium sp. belonging to the Rhizobium clade that includes R. daejeonense, R....

  13. Nickel: A micronutrient element for hydrogen-dependent growth of Rhizobium japonicum and for expression of urease activity in soybean leaves

    PubMed Central

    Klucas, Robert V.; Hanus, F. Joe; Russell, Sterling A.; Evans, Harold J.

    1983-01-01

    Soybean plants and Rhizobium japonicum 122 DES, a hydrogen uptake-positive strain, were cultured in media purified to remove Ni. Supplemental Ni had no significant effect on the dry matter or total N content of plants. However, the addition of Ni to both nitrate-grown and symbiotically grown plants resulted in a 7- to 10-fold increase in urease activity (urea amidohydrolase, EC 3.5.1.5) in leaves and significantly increased the hydrogenase activity (EC 1.18.3.1) in isolated nodule bacteroids. When cultured under chemolithotrophic conditions, free-living R. japonicum required Ni for growth and for the expression of hydrogenase activity. Hydrogenase activity was minimal or not detectable in cells incubated either without Ni or with Ni and chloramphenicol. Ni is required for derepression of hydrogenase activity and apparently protein synthesis is necessary for the participation of Ni in hydrogenase expression. The addition of Cr, V, Sn, and Pb in place of Ni failed to stimulate the activity of hydrogenase in R. japonicum and urease in soybean leaves. The evidence indicates that Ni is an important micronutrient element in the biology of the soybean plant and R. japonicum. PMID:16578770

  14. Genomic Diversity of Enterotoxigenic Strains of Bacteroides fragilis.

    PubMed

    Pierce, Jessica V; Bernstein, Harris D

    2016-01-01

    Enterotoxigenic (ETBF) strains of Bacteroides fragilis are the subset of strains that secrete a toxin called fragilysin (Bft). Although ETBF strains are known to cause diarrheal disease and have recently been associated with colorectal cancer, they have not been well characterized. By sequencing the complete genome of four ETBF strains, we found that these strains exhibit considerable variation at the genomic level. Only a small number of genes that are located primarily in the Bft pathogenicity island (BFT PAI) and the flanking CTn86 conjugative transposon are conserved in all four strains and a fifth strain whose genome was previously sequenced. Interestingly, phylogenetic analysis strongly suggests that the BFT PAI was acquired by non-toxigenic (NTBF) strains multiple times during the course of evolution. At the phenotypic level, we found that the ETBF strains were less fit than the NTBF strain NCTC 9343 and were susceptible to a growth-inhibitory protein that it produces. The ETBF strains also showed a greater tendency to form biofilms, which may promote tumor formation, than NTBF strains. Although the genomic diversity of ETBF strains raises the possibility that they vary in their pathogenicity, our experimental results also suggest that they share common properties that are conferred by different combinations of non-universal genetic elements. PMID:27348220

  15. Determination of some in vitro growth requirements of Bacteroides nodosus.

    PubMed

    Skerman, T M

    1975-03-01

    Physical and nutritional factors required for growth of Bacteroides nodosus isolates from ovine foot-rot lesions were examined. Simplified anaerobic culture techniques were devised utilizing a fully soluble, autoclavable, liquid medium (TAS) which contained proteose-peptone, yeast and meat extracts and certain other essential compounds required to promote prompt and serially transferrable growth of cultures from small inocula. The latter included Trypticase, arginine, a reducing agent (most suitably thioglycollic acid) and CO2; serine and Mg2+ markedly increased growth yields. Trypticase could not be replaced by a commercial preparation of acid-hydrolysed casein; other forms of hydrolysed protein gave delayed and inconsistent growth. Maximum growth of cultures required concentrations of 0-02 to 0-35 M-arginine, which could not be replaced by glutamic acid, citrulline or ornithine. Exogenous carbohydrate compounds were not required. The temperature range for optimum growth of cultures was 37 to 39 degrees C, and anaerobic culture conditions were essential for growth and the production of B. nodosus organisms of normal morphology. Solidified TAS media for the isolation and maintenance of B. nodosus cultures were also devised. PMID:1133574

  16. In vitro utilization of mucin by Bacteroides fragilis.

    PubMed Central

    Roberton, A M; Stanley, R A

    1982-01-01

    A method for isolating pig colon mucin in a soluble high-molecular-weight form, suitable for addition to bacterial growth media, is described. This preparation was utilized as a sole carbohydrate energy source by two strains of Bacteroides fragilis. The extent of degradation was compared with that of commercial pig gastric mucin by the same strains. Gas-liquid chromatographic analysis of the mucin carbohydrates and gel chromatography of the preparations were carried out before and after in vitro degradation. The mucin carbohydrates were utilized only to a very limited extent, colon mucin being more resistant to degradation than gastric mucin. Both mucins chromatographed at or near the excluded volume on Sepharose 4B, and only in the case of ATCC 25285 grown on gastric mucin was a significant degradation peak detected. If mucins are degraded in vivo by the sequential action of several bacteria, a pure culture in vitro might be expected to degrade mucins to a limited extent only. Techniques previously used to examine mucin utilization by pure cultures may have overlooked limited mucin degradation demonstrated by the methods used in this work. PMID:6174077

  17. Genomic Diversity of Enterotoxigenic Strains of Bacteroides fragilis

    PubMed Central

    Pierce, Jessica V.; Bernstein, Harris D.

    2016-01-01

    Enterotoxigenic (ETBF) strains of Bacteroides fragilis are the subset of strains that secrete a toxin called fragilysin (Bft). Although ETBF strains are known to cause diarrheal disease and have recently been associated with colorectal cancer, they have not been well characterized. By sequencing the complete genome of four ETBF strains, we found that these strains exhibit considerable variation at the genomic level. Only a small number of genes that are located primarily in the Bft pathogenicity island (BFT PAI) and the flanking CTn86 conjugative transposon are conserved in all four strains and a fifth strain whose genome was previously sequenced. Interestingly, phylogenetic analysis strongly suggests that the BFT PAI was acquired by non-toxigenic (NTBF) strains multiple times during the course of evolution. At the phenotypic level, we found that the ETBF strains were less fit than the NTBF strain NCTC 9343 and were susceptible to a growth-inhibitory protein that it produces. The ETBF strains also showed a greater tendency to form biofilms, which may promote tumor formation, than NTBF strains. Although the genomic diversity of ETBF strains raises the possibility that they vary in their pathogenicity, our experimental results also suggest that they share common properties that are conferred by different combinations of non-universal genetic elements. PMID:27348220

  18. Novel oligosaccharide constituents of the cellulase complex of Bacteroides cellulosolvens.

    PubMed

    Gerwig, G J; Kamerling, J P; Vliegenthart, J F; Morag, E; Lamed, R; Bayer, E A

    1992-04-15

    The multiple cellulase-containing protein complex, isolated from the cellulolytic bacterium Bacteroides cellulosolvens, contains oligosaccharides which are O-linked mainly to a 230-kDa subunit. The oligosaccharide chains were liberated by alkaline-borohydride treatment and fractionated as oligosaccharide alditols via gel-permeation chromatography and HPLC. The fractions were investigated by one- and two-dimensional (correlation, homonuclear Hartmann-Hahn, rotating-frame nuclear Overhauser enhancement) 500-MHz 1H-NMR spectroscopy in combination with monosaccharide and methylation analyses and with fast-atom-bombardment mass spectrometry. The following carbohydrate structures could be established: [formula: see text] The results indicate an interesting similarity between the oligosaccharide moieties of the cellulase complex of B. cellulosolvens and of Clostridium thermocellum [Gerwig, G. J., Kamerling, J. P., Vliegenthart, J. F. G., Morag (Morgenstern), E., Lamed, R. & Bayer, E. A. (1991) Eur. J. Biochem. 196, 115-122], having 3, 5 and 6 as common elements. The furanose form of a terminal alpha-D-galactose residue demonstrated an inhibitory effect on the interaction of Griffonia simplicifolia I isolectin B4 with the cellulosome-like entity of B. cellulosolvens. PMID:1572372

  19. Sphingolipid synthesis deficiency in a mutant of Bacteroides levii

    SciTech Connect

    Brumleve, B.; Lev, M.

    1986-05-01

    Bacteroides levii, an anaerobic bacterium, synthesizes two sphingolipids; the sphingomyelin analogue, ceramide phosphorylethanolamine (CPE), and also ceramide phosphorylglycerol (CPG). The first enzyme in the sphingolipid pathway, 3-ketodihydro-sphingosine (3KDS) synthase, has been partially purified previously. To study subsequent steps in the pathways, mutants defective in sphingolipid synthesis were derived by ethyl methanesulfonate and nitrosoguanidine mutagenesis. Extracts of the mutant, 1075BB, show synthase activity although the cells do not synthesize CPE or CPG. The mutant differs from the wild type in that: (1) synthase activity was much diminished in the mutant, (2) sphingolipid synthesis does not occur in the mutant as evidenced by the absence of spots at sites where CPE and CPG migrate following two-dimensional thin layer chromatography, (3) incorporation of uniformly-labelled (/sup 14/C)serine carbon or (/sup 14/C)3KDS into sphingolipids was not observed in the mutant, (4) following incubation with (/sup 14/C)3KDS, radioactivity corresponding to dihydrosphingosine (DHS) and ceramide were observed in the mutant; no (/sup 14/C)DHS was detected in the wild type, and (5) enhanced incorporation of (/sup 14/C)serine carbon into two lipids not containing phosphorus was found in the mutant. The authors conclude, therefore, that this mutant, 1075BB, has a metabolic block at the terminal biosynthetic steps of sphingolipid synthesis.

  20. DNA Inversion Regulates Outer Membrane Vesicle Production in Bacteroides fragilis

    PubMed Central

    Nakayama-Imaohji, Haruyuki; Hirota, Katsuhiko; Yamasaki, Hisashi; Yoneda, Saori; Nariya, Hirofumi; Suzuki, Motoo; Secher, Thomas; Miyake, Yoichiro; Oswald, Eric; Hayashi, Tetsuya; Kuwahara, Tomomi

    2016-01-01

    Phase changes in Bacteroides fragilis, a member of the human colonic microbiota, mediate variations in a vast array of cell surface molecules, such as capsular polysaccharides and outer membrane proteins through DNA inversion. The results of the present study show that outer membrane vesicle (OMV) formation in this anaerobe is also controlled by DNA inversions at two distantly localized promoters, IVp-I and IVp-II that are associated with extracellular polysaccharide biosynthesis and the expression of outer membrane proteins. These promoter inversions are mediated by a single tyrosine recombinase encoded by BF2766 (orthologous to tsr19 in strain NCTC9343) in B. fragilis YCH46, which is located near IVp-I. A series of BF2766 mutants were constructed in which the two promoters were locked in different configurations (IVp-I/IVp-II = ON/ON, OFF/OFF, ON/OFF or OFF/ON). ON/ON B. fragilis mutants exhibited hypervesiculating, whereas the other mutants formed only a trace amount of OMVs. The hypervesiculating ON/ON mutants showed higher resistance to treatment with bile, LL-37, and human β-defensin 2. Incubation of wild-type cells with 5% bile increased the population of cells with the ON/ON genotype. These results indicate that B. fragilis regulates the formation of OMVs through DNA inversions at two distantly related promoter regions in response to membrane stress, although the mechanism underlying the interplay between the two regions controlled by the invertible promoters remains unknown. PMID:26859882

  1. Ultrastructure of the Bacteroides nodosus cell envelope layers and surface.

    PubMed Central

    Every, D; Skerman, T M

    1980-01-01

    The surface structure and cell envelope layers of various virulent Bacteroides nodosus strains were examined by light microscopy and by electron microscopy by using negative staining, thin-section, and freeze-fracture-etch techniques. Three surface structures were described: pili and a diffuse material, both of which emerged from one or both poles of the bacteria (depending on the stage of growth and division), and large rodlike structures (usually 30 to 40 nm in diameter) associated with a small proportion of the bacterial population. No capsule was detected. The cell envelope consisted of four layers: a plasma membrane, a peptidoglycan layer, an outer membrane, and an outermost additional layer. The additional layer was composed of subunits, generally hexagonally packed with center-to-center spacing of 6 to 7 nm. The outer membrane and plasma membrane freeze-fractured through their hydrophobic regions revealing four fracture faces with features similar to those of other gram-negative bacteria. However, some unusual features were seen on the fracture faces of the outer membrane: large raised ring structure (11 to 12 nm in diameter) on cw 3 at the poles of the bacteria; complementary pits or ring-shaped depressions on cw 2; and small raised ring structures (7 to 8 nm in diameter) all over cw 2. Images PMID:6154040

  2. Suppurative otitis and ascending meningoencephalitis associated with Bacteroides tectus and Porphyromonas gulae in a captive Parma wallaby (Macropus parma) with toxoplasmosis.

    PubMed

    Giannitti, Federico; Schapira, Andrea; Anderson, Mark; Clothier, Kristin

    2014-09-01

    A 6-year-old female Parma wallaby (Macropus parma) at a zoo in California developed acute ataxia and left-sided circling. Despite intensive care, clinical signs progressed to incoordination and prostration, and the animal was euthanized. At necropsy, the left tympanic cavity was filled with homogeneous suppurative exudate that extended into the cranium expanding the meninges and neuroparenchyma in the lateral and ventral aspect of the caudal ipsilateral brainstem and medulla oblongata. Microscopically, the brainstem showed regional severe suppurative meningoencephalitis with large numbers of neutrophils, fewer macrophages, and lymphocytes admixed with fibrin, necrotic cellular debris, hemorrhage, and mineralization, with numerous intralesional Gram-negative bacilli. Bacteroides spp. and Porphyromonas spp. were isolated on anaerobic culture from the meninges, and the bacteria were further characterized by partial 16S ribosomal RNA gene sequencing as Bacteroides tectus and Porphyromonas gulae. Bacterial aerobic culture from the meninges yielded very low numbers of mixed flora and Proteus spp., which were considered contaminants. Culture of Mycoplasma spp. from middle ear and meninges was negative. Additionally, Toxoplasma gondii cysts were detected by immunohistochemistry in the heart and brain, and anti-Toxoplasma antibodies were detected in serum. The genera Bacteroides and Porphyromonas have been associated with oral disease in marsupials; but not with otitis and meningoencephalitis. The results of the present work highlight the importance of performing anaerobic cultures in the diagnostic investigation of cases of suppurative otitis and meningoencephalitis in macropods. PMID:25057163

  3. Genetic snapshots of the Rhizobium species NGR234 genome

    PubMed Central

    Viprey, Virginie; Rosenthal, André; Broughton, William J; Perret, Xavier

    2000-01-01

    Background: In nitrate-poor soils, many leguminous plants form nitrogen-fixing symbioses with members of the bacterial family Rhizobiaceae. We selected Rhizobium sp. NGR234 for its exceptionally broad host range, which includes more than I 12 genera of legumes. Unlike the genome of Bradyrhizobium japonicum, which is composed of a single 8.7 Mb chromosome, that of NGR234 is partitioned into three replicons: a chromosome of about 3.5 Mb, a megaplasmid of more than 2 Mb (pNGR234b) and pNGR234a, a 536,165 bp plasmid that carries most of the genes required for symbioses with legumes. Symbiotic loci represent only a small portion of all the genes coded by rhizobial genomes, however. To rapidly characterize the two largest replicons of NGR234, the genome of strain ANU265 (a derivative strain cured of pNGR234a) was analyzed by shotgun sequencing. Results: Homology searches of public databases with 2,275 random sequences of strain ANU265 resulted in the identification of 1,130 putative protein-coding sequences, of which 922 (41%) could be classified into functional groups. In contrast to the 18% of insertion-like sequences (ISs) found on the symbiotic plasmid pNGR234a, only 2.2% of the shotgun sequences represent known ISs, suggesting that pNGR234a is enriched in such elements. Hybridization data also indicate that the density of known transposable elements is higher in pNGR234b (the megaplasmid) than on the chromosome. Rhizobium-specific intergenic mosaic elements (RIMEs) were found in 35 shotgun sequences, 6 of which carry RIME2 repeats previously thought to be present only in Rhizobium meliloti. As non-overlapping shotgun sequences together represent approximately 10% of ANU265 genome, the chromosome and megaplasmid may carry a total of over 200 RIMEs. Conclusions: 'Skimming' the genome of Rhizobium sp. NGR234 sheds new light on the fine structure and evolution of its replicons, as well as on the integration of symbiotic functions in the genome of a soil bacterium

  4. Comparative properties of glutamine synthetases I and II in Rhizobium and Agrobacterium spp.

    PubMed Central

    Fuchs, R L; Keister, D L

    1980-01-01

    Some properties of glutamine synthetase I (GSI) and GSII are described for a fast-growing Rhizobium sp. (Rhizobium trifolii T1), a slow-growing Rhizobium sp. (Rhizobium japonicum USDA 83), and Agrobacterium tumefaciens C58. GSII of the fast-growing Rhizobium sp. and GSII of the Agrobacterium sp. were considerably more heat labile than GSII of the slow-growing Rhizobium sp. As previously shown in R. japonicum 61A76, GSI became adenylylated rapidly in all species tested in response to ammonium. GSII activity disappeared within one generation of growth in two of the strains, but the disappearance of GSII activity required two generations in another. Isoactivity points for transferase assay, which were derived from the pH curves of adenylylated GSI and deadenylylated GSI, were approximately pH 7.8 for both R. trifolii and A. tumefaciens. No isoactivity point was found for R. japonicum under the standard assay conditions used. When the feedback inhibitor glycine was used to inhibit differentially the adenylylated GSI and deadenylylated GSI of R. japonicum, an isoactivity point was observed at pH 7.3. Thus, the transferase activity of GSI could be determined independent of the state of adenylation. A survey of 23 strains of bacteria representing 11 genera indicated that only Rhizobium spp. and Agrobacterium spp. contained GSII. Thus, this enzyme appears to be unique for the Rhizobiaceae. PMID:6107288

  5. Relative adherence of Bacteroides species and strains to Actinomyces viscosus on saliva-coated hydroxyapatite

    SciTech Connect

    Li, J.; Ellen, R.P. )

    1989-09-01

    The study was designed to compare the adherence of several Bacteroides species to A. viscosus. Using 3H, we labeled 24 laboratory strains, including 13 Bacteroides species and 11 fresh clinical isolates of three Bacteroides species. Their adherence to A. viscosus bound to a saliva-coated mineral surface was quantified by liquid scintillation. Adherence relative to a standard strain, B. gingivalis 2561, was compared. Among the lab bacteroides, those of B. gingivalis (eight strains) were the greatest binders (mean, 80.5 {plus minus} 12.4%). Strains of other lab bacteroides bound less well (mean, 33.4 {plus minus} 6.3%). The difference in means was statistically significant (p less than 0.01). The mean for B. gingivalis strains was also significantly greater than that for strains of B. intermedius (51.7 {plus minus} 6.2%). Attachment of B. gingivalis was saturable in experiments in which either input concentration or time was the independent variable, indicating that B. gingivalis cells do not accumulate in this vitro simulation of plaque formation by binding to each other. Subculture did not seem to affect the degree of binding.

  6. Fate of Nodule-Specific Polysaccharide Produced by Bradyrhizobium japonicum Bacteroids.

    PubMed

    Streeter, J. G.; Peters, N. K.; Salminen, S. O.; Pladys, D.; Zhaohua, P.

    1995-03-01

    A polysaccharide produced by Bradyrhizobium japonicum bacteroids in nodules (NPS) on soybean (Glycine max [L.] Merr.) roots is different in composition and structure from the extracellular polysaccharide produced in culture by this organism. Isogenic strains either capable or incapable of NPS synthesis supported similar rates of plant growth and nitrogenase activity, indicating that polysaccharide deposition was not detrimental. The possibility that NPS may have some protective or nutritional role for bacteroids was considered. Analysis of disintegrating nodules over periods of 1 to 3 months indicated greater recovery of viable bacteria from NPS+ nodules prior to the breakdown of NPS. During and after the breakdown of NPS, the decline in viable bacteria was similar for NPS+ and NPS- strains. Bacteroid destruction in senescing nodules may be accelerated by exposure to proteolytic enzymes in host cytoplasm; however, highly purified NPS had no significant effect on the in vitro activity of partially purified proteases, so protection of bacteroids via this mechanism is unlikely. B. japonicum USDA 438 did not utilize NPS as a carbon source for growth in liquid culture. In vitro assays of NPS depolymerase activity in cultured bacteria and bacteroids were negative using a variety of strains, all of which contained extracellular polysaccharide depolymerase. It seems highly unlikely that B. japonicum can utilize the polysaccharide it synthesizes in nodules, and NPS breakdown in senescing nodules is probably caused by saprophytic fungi. PMID:12228408

  7. A Phase-Variable Surface Layer from the Gut Symbiont Bacteroides thetaiotaomicron

    PubMed Central

    Taketani, Mao; Donia, Mohamed S.; Jacobson, Amy N.; Lambris, John D.

    2015-01-01

    ABSTRACT The capsule from Bacteroides, a common gut symbiont, has long been a model system for studying the molecular mechanisms of host-symbiont interactions. The Bacteroides capsule is thought to consist of an array of phase-variable polysaccharides that give rise to subpopulations with distinct cell surface structures. Here, we report the serendipitous discovery of a previously unknown surface structure in Bacteroides thetaiotaomicron: a surface layer composed of a protein of unknown function, BT1927. BT1927, which is expressed in a phase-variable manner by ~1:1,000 cells in a wild-type culture, forms a hexagonally tessellated surface layer. The BT1927-expressing subpopulation is profoundly resistant to complement-mediated killing, due in part to the BT1927-mediated blockade of C3b deposition. Our results show that the Bacteroides surface structure is capable of a far greater degree of structural variation than previously known, and they suggest that structural variation within a Bacteroides species is important for productive gut colonization. PMID:26419879

  8. Fate of Nodule-Specific Polysaccharide Produced by Bradyrhizobium japonicum Bacteroids.

    PubMed Central

    Streeter, J. G.; Peters, N. K.; Salminen, S. O.; Pladys, D.; Zhaohua, P.

    1995-01-01

    A polysaccharide produced by Bradyrhizobium japonicum bacteroids in nodules (NPS) on soybean (Glycine max [L.] Merr.) roots is different in composition and structure from the extracellular polysaccharide produced in culture by this organism. Isogenic strains either capable or incapable of NPS synthesis supported similar rates of plant growth and nitrogenase activity, indicating that polysaccharide deposition was not detrimental. The possibility that NPS may have some protective or nutritional role for bacteroids was considered. Analysis of disintegrating nodules over periods of 1 to 3 months indicated greater recovery of viable bacteria from NPS+ nodules prior to the breakdown of NPS. During and after the breakdown of NPS, the decline in viable bacteria was similar for NPS+ and NPS- strains. Bacteroid destruction in senescing nodules may be accelerated by exposure to proteolytic enzymes in host cytoplasm; however, highly purified NPS had no significant effect on the in vitro activity of partially purified proteases, so protection of bacteroids via this mechanism is unlikely. B. japonicum USDA 438 did not utilize NPS as a carbon source for growth in liquid culture. In vitro assays of NPS depolymerase activity in cultured bacteria and bacteroids were negative using a variety of strains, all of which contained extracellular polysaccharide depolymerase. It seems highly unlikely that B. japonicum can utilize the polysaccharide it synthesizes in nodules, and NPS breakdown in senescing nodules is probably caused by saprophytic fungi. PMID:12228408

  9. The enterotoxin of Bacteroides fragilis is a metalloprotease.

    PubMed Central

    Moncrief, J S; Obiso, R; Barroso, L A; Kling, J J; Wright, R L; Van Tassell, R L; Lyerly, D M; Wilkins, T D

    1995-01-01

    During the past decade, strains of Bacteroides fragilis that produce an enterotoxin have been implicated in diarrheal disease in animals and humans. The extracellular enterotoxin has been purified and characterized as a single polypeptide (M(r), approximately 20,000). Single specific primer-PCR was used to clone a portion of the B. fragilis enterotoxin gene. The recombinant protein expressed by the cloned gene fragment reacted with monospecific antibodies to B. fragilis enterotoxin by enzyme-linked immunosorbent assay and immunoblot analysis. The deduced amino acid sequence revealed a signature zinc-binding consensus motif (HEXXHXXGXXH/Met-turn) characteristic of metalloproteases termed metzincins. Sequence comparisons showed close identity to matrix metalloproteases (e.g., human fibroblast collagenase) within the zinc-binding and Met-turn region. Purified enterotoxin contained 1 g-atom of Zn2+ per molecule and hydrolyzed gelatin, azocoll, actin, tropomyosin, and fibrinogen. The enterotoxin also underwent autodigestion. The N-terminal amino acid sequences of two autodigestion products were identical to the deduced amino acid sequence of the recombinant enterotoxin and revealed cleavage at Cys-Leu and Ser-Leu peptide bonds. Gelatinase (type IV collagenase) activity comigrated with the toxin when analyzed by gel fractionation and zymography, indicating that protease activity is due to the enterotoxin and not to a contaminating protease(s). Optimal proteolytic activity occurred at 37 degrees C and pH 6.5. Primary proteolytic cleavage sites in actin were identified, revealing cleavage at Gly-Met and Thr-Leu peptide bonds. Enzymatic activity was inhibited by metal chelators but not by inhibitors of other classes of proteases. Additionally, cytotoxic activity of the enterotoxin on human carcinoma HT-29 cells was inhibited by acetoxymethyl ester EDTA. The metalloprotease activity of the enterotoxin suggests a possible mechanism for enterotoxicity and may have additional

  10. Characterization of an outer membrane mannanase from Bacteroides ovatus.

    PubMed Central

    Gherardini, F C; Salyers, A A

    1987-01-01

    Bacteroides ovatus utilizes guar gum, a high-molecular-weight branched galactomannanan, as a sole source of carbohydrate. No extracellular activity was detectable. Approximately 30% of the total cell-associated mannanase activity partitioned with cell membranes. When inner and outer membranes of B. ovatus were separated on sucrose gradients, the mannanase activity was associated mainly with fractions containing outer membranes. Enzyme activity was solubilized by 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) or by Triton X-100 at a detergent-to-protein ratio of 1:1. The enzyme was stable for only 4 h at 37 degrees C and for 50 to 60 h at 4 degrees C. Analysis of the products of the CHAPS-solubilized mannanase on Bio-Gel A-5M and Bio-Gel P-10 gel filtration columns indicated that the enzyme breaks guar gum into high-molecular-weight fragments. The CHAPS-solubilized mannanase was partially purified by chromatography on a FPLC Mono Q column. The partially purified mannanase preparation contained three major polypeptides (Mr 94,500, 61,000, and 43,000) and several minor ones. High mannanase activity was seen only when B. ovatus was grown on guar gum. Cross-absorbed antiserum detected two other guar gum-associated outer membrane proteins: a CHAPS-extractable 49,000-dalton polypeptide and a 120,000-dalton polypeptide that was not solubilized by CHAPS. Neither of these polypeptides was detectable in the partially purified mannanase preparation. These results indicate that there are at least two guar gum-associated outer membrane polypeptides other than the mannanase. Images PMID:3553153

  11. NolL of Rhizobium sp. Strain NGR234 Is Required for O-Acetyltransferase Activity

    PubMed Central

    Berck, S.; Perret, X.; Quesada-Vincens, D.; Promé, J.-C.; Broughton, W. J.; Jabbouri, S.

    1999-01-01

    Following (iso)flavonoid induction, nodulation genes of the symbiotic nitrogen-fixing bacterium Rhizobium sp. strain NGR234 elaborate a large family of lipooligosaccharidic Nod factors (NodNGR factors). When secreted into the rhizosphere of compatible legumes, these signal molecules initiate root hair deformation and nodule development. The nonreducing glucosamine residue of NodNGR factors are N acylated, N methylated, and mono- or biscarbamoylated, while position C-6 of the reducing extremity is fucosylated. This fucose residue is normally 2-O methylated and either sulfated or acetylated. Here we present an analysis of all acetylated NodNGR factors, which clearly shows that the acetate group may occupy position C-3 or C-4 of the fucose moiety. Disruption of the flavonoid-inducible nolL gene, which is preceded by a nod box, results in the synthesis of NodNGR factors that lack the 3-O- or 4-O-acetate groups. Interestingly, the nodulation capacity of the mutant NGRΩnolL is not impaired, whereas introduction of the nod box::nolL construct into the related strain Rhizobium fredii USDA257 extends the host range of this bacterium to Calopogonium caeruleum, Leucaena leucocephala, and Lotus halophilus. Nod factors produced by a USDA257(pnolL) transconjugant were also acetylated. The nod box::nolL construct was also introduced into ANU265 (NGR234 cured of its symbiotic plasmid), along with extra copies of the nodD1 gene. When permeabilized, these cells possessed acetyltransferase activity, although crude extracts did not. PMID:9922261

  12. [Infective endocarditis by Rhizobium radiobacter. A case report].

    PubMed

    Piñerúa Gonsálvez, Jean Félix; Zambrano Infantinot, Rosanna del Carmen; Calcaño, Carlos; Montaño, César; Fuenmayor, Zaida; Rodney, Henry; Rodney, Marianela

    2013-03-01

    Rhizobium radiobacter is a Gram-negative, nitrogen-fixing bacterium, which is found mainly on the ground. It rarely causes infections in humans. It has been associated with bacteremia, secondary to colonization of intravascular catheters, in immunocompromised patients. The aim of this paper was to report the case of an infective endocarditis caused by R. radiobacter, in a 47-year-old male, diagnosed with chronic kidney disease stage 5, on replacement therapy with hemodialysis and who attended the medical center with fever of two weeks duration. The patient was hospitalized and samples of peripheral blood were taken for culture. Empirical antibiotic therapy was started with cefotaxime plus vancomycin. The transthoracic echocardiogram revealed fusiform vegetation on the tricuspid valve, with grade III-IV/IV regurgitation. On the seventh day after the start of antibiotic therapy, the patient had a clinical and paraclinical improvement. The bacterium identified by blood culture was Rhizobium radiobacter, ceftriaxone-resistant and sensitive to imipenem, amikacin, ampicillin and ampicillin/sulbactam. Because of the clinical improvement, it was decided to continue treatment with vancomycin and additionally, with imipenem. At 14 days after the start of antibiotic therapy, the patient was discharged with outpatient treatment with imipenem up to six weeks of treatment. The control echocardiogram showed the absence of vegetation on the tricuspid valve. This case suggests that R. radiobacter can cause endocarditis in patients with intravascular catheters. PMID:23781714

  13. A partial phylogenetic analysis of the "flavobacter-bacteroides" phylum: basis for taxonomic restructuring

    NASA Technical Reports Server (NTRS)

    Gherna, R.; Woese, C. R.

    1992-01-01

    On the basis of small subunit rRNA sequence analyses five major subgroups within the flavobacteria-bacteroides phylum have been defined. These are tentatively designated the cytophaga subgroup (comprising largely Cytophaga species), the flavobacter subgroup (comprising the true flavobacteria and the polyphyletic genus Weeksella), the bacteroides subgroup (comprising the bacteroides and certain cytophaga-like bacteria), the sphingobacter subgroup (which contains the known sphingolipid-producing members of the phylum), and the saprospira subgroup (comprising particular species of Flexibacter, Flavobacterium, Haliscomenobacter, and, of course, the genus Saprospira). These groupings are given not only by evolutionary distance analysis, but can be defined and distinguished on the basis of a simple small subunit rRNA signatures.

  14. Migration and chemiluminescence of polymorphonuclear cells and monocytes to Bacteroides sonicates.

    PubMed

    Fotos, P G; Lewis, D M; Gerencser, V F; Gerencser, M A; Snyder, I S

    1992-01-01

    Recent investigations have demonstrated that various preparations obtained from representatives of the genus Bacteroides are poorly phagocytized by polymorphonuclear cells (PMN) and macrophages. Crude cell sonicates derived from Bacteroides have been examined for their ability to inhibit migration of PMN and monocytes using a modified migration under agarose in vitro assay. B. gingivalis and B. intermedius were found to be inhibitors of such migration while B. asaccharolyticus did not share this property (P less than 0.005). In addition, B. intermedius sonicates were found to inhibit PMN chemiluminescence to known stimulants (P less than 0.001). These data were not found to result from direct sonicate cytotoxicity and therefore lend additional support to the etiologic importance of specific Bacteroides strains in the pathogenesis of acute and chronic dentoalveolar infections. PMID:1321583

  15. A novel strain of Bacteroides fragilis enhances phagocytosis and polarises M1 macrophages

    PubMed Central

    Deng, Huimin; Li, Zhengchao; Tan, Yafang; Guo, Zhaobiao; Liu, Yangyang; Wang, Ye; Yuan, Yuan; Yang, Ruifu; Bi, Yujing; Bai, Yang; Zhi, Fachao

    2016-01-01

    Commensal Bacteroides fragilis possesses immune-regulatory characteristics. Consequently, it has been proposed as a potential novel probiotic because of its therapeutic effects on immune imbalance, mental disorders and inflammatory diseases. Macrophages play a central role in the immune response, developing either a classical-M1 or an alternative-M2 phenotype after stimulation with various signals. The interactions between macrophages and B. fragilis, however, remain to be defined. Here, a new isolate of B. fragilis, ZY-312, was shown to possess admirable properties, including tolerance to simulated gastric fluid, intestinal fluid and ox bile, and good safety (MOI = 100, 200) and adherent ability (MOI = 100) to LoVo cells. Isolate ZY-312 cell lysate promoted phagocytosis of fluorescent microspheres and pathogenic bacteria in bone marrow-derived macrophage (BMDM) cells. Gene expression of IL-12, iNOS and IL-1β in BMDM cells was increased after treatment with ZY-312, indicating the induction of M1 macrophages, consistent with enhanced secretion of NO. Cell surface expression of CD80 and CD86 was also increased. This study is the first to demonstrate that B. fragilis enhances the phagocytic functions of macrophages, polarising them to an M1 phenotype. Our findings provide insight into the close relationship between B. fragilis and the innate immune system. PMID:27381366

  16. A novel strain of Bacteroides fragilis enhances phagocytosis and polarises M1 macrophages.

    PubMed

    Deng, Huimin; Li, Zhengchao; Tan, Yafang; Guo, Zhaobiao; Liu, Yangyang; Wang, Ye; Yuan, Yuan; Yang, Ruifu; Bi, Yujing; Bai, Yang; Zhi, Fachao

    2016-01-01

    Commensal Bacteroides fragilis possesses immune-regulatory characteristics. Consequently, it has been proposed as a potential novel probiotic because of its therapeutic effects on immune imbalance, mental disorders and inflammatory diseases. Macrophages play a central role in the immune response, developing either a classical-M1 or an alternative-M2 phenotype after stimulation with various signals. The interactions between macrophages and B. fragilis, however, remain to be defined. Here, a new isolate of B. fragilis, ZY-312, was shown to possess admirable properties, including tolerance to simulated gastric fluid, intestinal fluid and ox bile, and good safety (MOI = 100, 200) and adherent ability (MOI = 100) to LoVo cells. Isolate ZY-312 cell lysate promoted phagocytosis of fluorescent microspheres and pathogenic bacteria in bone marrow-derived macrophage (BMDM) cells. Gene expression of IL-12, iNOS and IL-1β in BMDM cells was increased after treatment with ZY-312, indicating the induction of M1 macrophages, consistent with enhanced secretion of NO. Cell surface expression of CD80 and CD86 was also increased. This study is the first to demonstrate that B. fragilis enhances the phagocytic functions of macrophages, polarising them to an M1 phenotype. Our findings provide insight into the close relationship between B. fragilis and the innate immune system. PMID:27381366

  17. Monoculture parameters successfully predict coculture growth kinetics of Bacteroides thetaiotaomicron and two Bifidobacterium strains.

    PubMed

    Van Wey, A S; Cookson, A L; Roy, N C; McNabb, W C; Soboleva, T K; Shorten, P R

    2014-11-17

    Microorganisms rarely live in isolation but are most often found in a consortium. This provides the potential for cross-feeding and nutrient competition among the microbial species, which make it challenging to predict the growth kinetics in coculture. In this paper we developed a mathematical model to describe substrate consumption and subsequent microbial growth and metabolite production for bacteria grown in monoculture. The model characterized substrate utilization kinetics of 18 Bifidobacterium strains. Some bifidobacterial strains demonstrated preferential degradation of oligofructose in that sugars with low degree of polymerization (DP) (DP≤3 or 4) were metabolized before sugars of higher DP, or vice versa. Thus, we expanded the model to describe the preferential degradation of oligofructose. In addition, we adapted the model to describe the competition between human colonic bacteria Bacteroides thetaiotaomicron LMG 11262 and Bifidobacterium longum LMG 11047 or Bifidobacterium breve Yakult for inulin as well as cross-feeding of breakdown products from the extracellular hydrolysis of inulin by B. thetaiotaomicron LMG 11262. We found that the coculture growth kinetics could be predicted based on the respective monoculture growth kinetics. Using growth kinetics from monoculture experiments to predict coculture dynamics will reduce the number of in vitro experiments required to parameterize multi-culture models. PMID:25282609

  18. Complete genome sequence of Bacteroides salanitronis type strain (BL78T)

    SciTech Connect

    Gronow, Sabine; Held, Brittany; Lucas, Susan; Lapidus, Alla L.; Glavina Del Rio, Tijana; Nolan, Matt; Tice, Hope; Deshpande, Shweta; Cheng, Jan-Fang; Pitluck, Sam; Liolios, Konstantinos; Pagani, Ioanna; Ivanova, N; Mavromatis, K; Pati, Amrita; Tapia, Roxanne; Han, Cliff; Goodwin, Lynne A.; Chen, Amy; Palaniappan, Krishna; Land, Miriam L; Hauser, Loren John; Chang, Yun-Juan; Jeffries, Cynthia; Brambilla, Evelyne-Marie; Rohde, Manfred; Goker, Markus; Detter, J. Chris; Woyke, Tanja; Bristow, James; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Eisen, Jonathan

    2011-01-01

    Bacteroides salanitronis Lan et al. 2006 is a species of the genus Bacteroides, which belongs to the family Bacteroidaceae. The species is of interest because it was isolated from the gut of a chicken and the growing awareness that the anaerobic microflora of the cecum is of benefit for the host and may impact poultry farming. The 4,308,663 bp long genome consists of a 4.24 Mbp chromosome and three plasmids (6 kbp, 19 kbp, 40 kbp) containing 3,737 protein-coding and 101 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  19. Cloning and characterization of the Bacteroides fragilis metalloprotease toxin gene.

    PubMed Central

    Franco, A A; Mundy, L M; Trucksis, M; Wu, S; Kaper, J B; Sears, C L

    1997-01-01

    Strains of Bacteroides fragilis that produce a ca. 20-kDa heat-labile protein toxin (termed B. fragilis toxin [BFT]) have been associated with diarrheal disease of animals and humans. BFT alters the morphology of intestinal epithelial cells both in vitro and in vivo and stimulates secretion in ligated intestinal segments of rats, rabbits, and lambs. Previous genetic and biochemical data indicated that BFT was a metalloprotease which hydrolyzed G (monomeric) actin, gelatin, and azocoll in vitro. In this paper, the cloning and sequencing of the entire B. fragilis toxin gene (bft) from enterotoxigenic B. fragilis (ETBF) 86-5443-2-2 is reported. The bft gene from this ETBF strain consists of one open reading frame of 1,191 nucleotides encoding a predicted 397-residue holotoxin with a calculated molecular weight of 44,493. Comparison of the predicted BFT protein sequence with the N-terminal amino acid sequence of purified BFT indicates that BFT is most probably synthesized by ETBF strains as a preproprotein. These data predict that BFT is processed to yield a biologically active toxin of 186 residues with a molecular mass of 20.7 kDa which is secreted into the culture supernatant. Analysis of the holotoxin sequence predicts a 20-residue amphipathic region at the carboxy terminus of BFT. Thus, in addition to the metalloprotease activity of BFT, the prediction of an amphipathic domain suggests that oligomerization of BFT may permit membrane insertion of the toxin with creation of a transmembrane pore. Comparison of the sequences available for the bft genes from ETBF 86-5443-2-2 and VPI 13784 revealed two regions of reduced homology. Hybridization of oligonucleotide probes specific for each bft to toxigenic B.fragilis strains revealed that 51 and 49% of toxigenic strains contained the 86-5433-2-2 and VPI 13784 bft genes, respectively. No toxigenic strain hybridized with both probes. We propose that these two subtypes of bft be termed bft-1 (VPI 13784) and bft-2 (86

  20. Survival of Rhizobium phaseoli in coal-based legume inoculants applied to seeds

    SciTech Connect

    Crawford, S.L.; Berryhill, D.L.

    1983-02-01

    Eight coals used as carriers in legume inoculants promoted the survival of Rhizobium phaseoli on pinto bean seeds. Although peat was more protective, most coal-based inoculants provided >10/sup 4/ viable rhizobia per seed after 4 weeks.

  1. (Basis for the competitiveness of Rhizobium japonicum in nodulation of soybean). Progress report, 1984

    SciTech Connect

    Bauer, W.D.; Evans, W.R.

    1984-01-01

    Those characteristics of Rhizobium cells that are most crucial in determining their competitive success when inoculated onto seed in the field are sought. Initial studies of Rhizobium attachment to root surfaces revealed that only a small subpopulation of the cells in an R. japonicum culture are capable of firmly attaching to soybean roots. The size of the attachment-competent subpopulation depends on strain and culture age. Attachment of rhizobia to roots was found to be linearly proportional to the bacterial concentration. The rate of attachment is constant under our conditions for approximately 60 min, then rapidly levels off to approximately zero. Once attached to the root surface, Rhizobium cells seldom spontaneously detach. Rhizobia of several different species all attached comparably well to soybean roots. Attachment of various Rhizobium species to the root hairs of soybean seedlings likewise showed no evidence of host specificity or selectivity. 2 figs., 2 tabs.

  2. Natural variation in symbiotic nitrogen-fixing Rhizobium and Frankia spp.

    PubMed

    Lie, T A; Akkermans, A D; van Egeraat, A W

    1984-01-01

    A description is given of the natural variation in nitrogen-fixing Rhizobium and Frankia spp. strains and the ability to form root nodules on compatible host plants. Arguments are given for the hypothesis that co-evolution has taken place through mutual interaction of host plants and indigenous Rhizobium and Frankia populations in the soil leading to most efficient symbiotic associations. The significance of root nodules as selective enrichment cultures of particular strains in natural and cultivated soils is exemplified by Rhizobium leguminosarum on various ecotypes of Pisum sativum and with Frankia sp. on various actinorhizal plants, in particular Alnus spp., in different geographic regions. The importance of a host-dependent distribution of Rhizobium and Frankia spp. for agriculture and forestry is discussed. PMID:6397130

  3. Expression of Rhizobium leguminosarum CFN42 genes for lipopolysaccharide in strains derived from different R. leguminosarum soil isolates

    SciTech Connect

    Brink, B.A.; Noel, K.D. ); Miller, J.; Carlson, R.W. )

    1990-02-01

    Two mutant derivatives of Rhizobium leguminosarum ANU843 defective in lipopolysaccharide (LPS) were isolated. The LPSs of both mutants lacked O antigen and some sugar residues of the LPS core oligosaccharides. Genetic regions previously cloned from another Rhizobium leguminosarum wild-type isolate, strain CFN42, were used to complement these mutants. One mutant was complemented to give LPS that was apparently identical to the LPS of strain ANU843 in antigenicity, electrophoretic mobility, and sugar composition. The other mutant was complemented by a second CFN42lps genetic region. In this case the resulting LPS contained O-antigen sugars characteristic of donor strain CFN42 and reacted weakly with antiserum against CFN42 cells, but did not react detectably with antiserum against ANU843 cells. Therefore, one of the CFN42 lps genetic regions specifies a function that is conserved between the two R. leguminosarum wild-type isolates, whereas the other region, at least in part, specifies a strain-specific LPS structure. Transfer of these two genetic regions into wild-type strains derived from R. leguminosarum ANU843 and 128C53 gave results consistent with this conclusion. The mutants derived from strain ANU843 elicited incompletely developed clover nodules that exhibited low bacterial populations and very low nitrogenase activity. Both mutants elicited normally developed, nitrogen-fixing clover nodules when they carried CFN42 lps DNA that permitted synthesis of O-antigen-containing LPS, regardless of whether the O antigen was the one originally made by strain ANU843.

  4. The celC gene, a new phylogenetic marker useful for taxonomic studies in Rhizobium.

    PubMed

    Robledo, Marta; Velázquez, Encarna; Ramírez-Bahena, Martha Helena; García-Fraile, Paula; Pérez-Alonso, Ana; Rivas, Raúl; Martínez-Molina, Eustoquio; Mateos, Pedro F

    2011-09-01

    The celC gene codifies for a cellulase that fulfils a very significant role in the infection process of clover by Rhizobium leguminosarum. This gene is located in the celABC operon present in the chromosome of strains representing R. leguminosarum, Rhizobium etli and Rhizobium radiobacter whose genomes have been completely sequenced. Nevertheless, the existence of this gene in other species of the genus Rhizobium had not been investigated to date. In this study, the celC gene was analysed for the first time in several species of this genus isolated from legume nodules and plant tumours, in order to compare the celC phylogeny to those of other chromosomal and plasmidic genes. The results obtained showed that phylogenies of celC and chromosomal genes, such as rrs, recA and atpD, were completely congruent, whereas no relation was found with symbiotic or virulence genes. Therefore, the suitability and usefulness of the celC gene to differentiate species of the genus Rhizobium, especially those with closely related rrs genes, was highlighted. Consequently, the taxonomic status of several strains of the genus Rhizobium with completely sequenced genomes is also discussed. PMID:21621937

  5. Dechlorination of Atrazine by a Rhizobium sp. Isolate

    PubMed Central

    Bouquard, C.; Ouazzani, J.; Prome, J.; Michel-Briand, Y.; Plesiat, P.

    1997-01-01

    A Rhizobium sp. strain, named PATR, was isolated from an agricultural soil and found to actively degrade the herbicide atrazine. Incubation of PATR in a basal liquid medium containing 30 mg of atrazine liter(sup-1) resulted in the rapid consumption of the herbicide and the accumulation of hydroxyatrazine as the only metabolite detected after 8 days of culture. Experiments performed with ring-labeled [(sup14)C]atrazine indicated no mineralization. The enzyme responsible for the hydroxylation of atrazine was partially purified and found to consist of four 50-kDa subunits. Its synthesis in PATR was constitutive. This new atrazine hydrolase demonstrated 92% sequence identity through a 24-amino-acid fragment with atrazine chlorohydrolase AtzA produced by Pseudomonas sp. strain ADP. PMID:16535552

  6. Lipopolysaccharide mutants of Rhizobium meliloti are not defective in symbiosis

    SciTech Connect

    Clover, R.H.; Kieber, J.; Signer, E.R. )

    1989-07-01

    Mutants of Rhizobium meliloti selected primarily for bacteriophage resistance fall into 13 groups. Mutants in the four best-characterized groups (class A, lpsB, lpsC, and class D), which map to the rhizobial chromosome, appear to affect lipopolysaccharide (LPS) as judged by the reactivity with monoclonal antibodies and behavior on sodium dodecyl sulfate-polyacrylamide gels of extracted LPS. Mutations in all 13 groups, in an otherwise wild-type genetic background, are Fix{sup +} on alfalfa. This suggests that LPS does not play a major role in symbiosis. Mutations in lpsB, however, are Fix{sup {minus}} in one particular genetic background, evidently because of the cumulative effect of several independent background mutations. In addition, an auxotrophic mutation evidently equivalent to Escherichia coli carAB is Fix{sup {minus}} on alfalfa.

  7. Acid tolerance of rhizobium trifolii in culture media

    SciTech Connect

    Thornton, F.C.; Davey, C.B.

    1983-01-01

    Tolerance to acidity (pH 4.2 to 4.6), low P (1 to 6 ..mu..M) and high Al (15 to 40..mu..M) for 100 strains of Rhizobium trifolii was assessed in liquid culture media in the laboratory. Response to acidity and Al varied among strains as evidenced by lower maximum cell densities and reduced growth rates, most preceded by a lag phase. Tolerance to acidity did not imply tolerance to Al in all cases. Strains were capable of tolerating higher levels of Al if acidity was reduced. Limitations in rhizobial growth due to low P concentrations were not as severe a stress as high acidity or high Al concentration.

  8. Rhizobium etli maize populations and their competitiveness for root colonization.

    PubMed

    Rosenblueth, Mónica; Martínez-Romero, Esperanza

    2004-05-01

    Rhizobium etli, which normally forms nitrogen-fixing nodules on Phaseolus vulgaris (common bean), is a natural maize endophyte. The genetic diversity of R. etli strains from bulk soil, bean nodules, the maize rhizosphere, the maize root, and inside stem tissue in traditional fields where maize is intercropped with P. vulgaris-beans was analyzed. Based on plasmid profiles and alloenzymes, it was determined that several R. etli types were preferentially encountered as putative maize endophytes. Some of these strains from maize were more competitive maize-root colonizers than other R. etli strains from the rhizosphere or from bean nodules. The dominant and highly competitive strain Ch24-10 was the most tolerant to 6-methoxy-2-benzoxazolinone (MBOA), a maize antimicrobial compound that is inhibitory to some bacteria and fungi. The R. tropici strain CIAT899, successfully used as inoculant of P. vulgaris, was also found to be a competitive maize endophyte in inoculation experiments. PMID:15024554

  9. Nodule initiation elicited by noninfective mutants of Rhizobium phaseoli.

    PubMed

    Vandenbosch, K A; Noel, K D; Kaneko, Y; Newcomb, E H

    1985-06-01

    Rhizobium phaseoli CE106, CE110, and CE115, originally derived by transposon mutagenesis (Noel et al., J. Bacteriol. 158:149-155, 1984), induced the formation of uninfected root nodule-like swellings on bean (Phaseolus vulgaris). Bacteria densely colonized the root surface, and root hair curling and initiation of root cortical-cell divisions occurred normally in mutant-inoculated seedlings, although no infection threads formed. The nodules were ineffective, lacked leghemoglobin, and were anatomically distinct from normal nodules. Ultrastructural specialization for ureide synthesis, characteristic of legumes that form determinate nodules, was absent. Colony morphology of the mutant strains on agar plates was less mucoid than that of the wild type, and under some cultural conditions, the mutants did not react with Cellufluor, a fluorescent stain for beta-linked polysaccharide. These observations suggest that the genetic lesions in these mutants may be related to extracellular polysaccharide synthesis. PMID:3997785

  10. Extensive Mobilome-Driven Genome Diversification in Mouse Gut-Associated Bacteroides vulgatus mpk

    PubMed Central

    Lange, Anna; Beier, Sina; Steimle, Alex; Autenrieth, Ingo B.; Huson, Daniel H.; Frick, Julia-Stefanie

    2016-01-01

    Like many other Bacteroides species, Bacteroides vulgatus strain mpk, a mouse fecal isolate which was shown to promote intestinal homeostasis, utilizes a variety of mobile elements for genome evolution. Based on sequences collected by Pacific Biosciences SMRT sequencing technology, we discuss the challenges of assembling and studying a bacterial genome of high plasticity. Additionally, we conducted comparative genomics comparing this commensal strain with the B. vulgatus type strain ATCC 8482 as well as multiple other Bacteroides and Parabacteroides strains to reveal the most important differences and identify the unique features of B. vulgatus mpk. The genome of B. vulgatus mpk harbors a large and diverse set of mobile element proteins compared with other sequenced Bacteroides strains. We found evidence of a number of different horizontal gene transfer events and a genome landscape that has been extensively altered by different mobilization events. A CRISPR/Cas system could be identified that provides a possible mechanism for preventing the integration of invading external DNA. We propose that the high genome plasticity and the introduced genome instabilities of B. vulgatus mpk arising from the various mobilization events might play an important role not only in its adaptation to the challenging intestinal environment in general, but also in its ability to interact with the gut microbiota. PMID:27071651

  11. Extensive Mobilome-Driven Genome Diversification in Mouse Gut-Associated Bacteroides vulgatus mpk.

    PubMed

    Lange, Anna; Beier, Sina; Steimle, Alex; Autenrieth, Ingo B; Huson, Daniel H; Frick, Julia-Stefanie

    2016-01-01

    Like many other Bacteroides species, Bacteroides vulgatus strain mpk, a mouse fecal isolate which was shown to promote intestinal homeostasis, utilizes a variety of mobile elements for genome evolution. Based on sequences collected by Pacific Biosciences SMRT sequencing technology, we discuss the challenges of assembling and studying a bacterial genome of high plasticity. Additionally, we conducted comparative genomics comparing this commensal strain with the B. vulgatus type strain ATCC 8482 as well as multiple other Bacteroides and Parabacteroides strains to reveal the most important differences and identify the unique features of B. vulgatus mpk. The genome of B. vulgatus mpk harbors a large and diverse set of mobile element proteins compared with other sequenced Bacteroides strains. We found evidence of a number of different horizontal gene transfer events and a genome landscape that has been extensively altered by different mobilization events. A CRISPR/Cas system could be identified that provides a possible mechanism for preventing the integration of invading external DNA. We propose that the high genome plasticity and the introduced genome instabilities of B. vulgatus mpk arising from the various mobilization events might play an important role not only in its adaptation to the challenging intestinal environment in general, but also in its ability to interact with the gut microbiota. PMID:27071651

  12. DESIGN AND EVALUATION OF BACTEROIDES DNA PROBES FOR THE SPECIFIC DETECTION OF HUMAN FECAL POLLUTION

    EPA Science Inventory

    Because Bacteroides spp. are obligate anaerobes that dominate the human fecal flora, and because some species may live only in the human intestine, these bacteria might be useful to distinguish human from nonhuman sources of fecal pollution. To test this hypothesis, PCR primers s...

  13. A proteomic approach towards understanding the cross talk between Bacteroides fragilis and Bifidobacterium longum in coculture.

    PubMed

    Rios-Covián, David; Sánchez, Borja; Martínez, Noelia; Cuesta, Isabel; Hernández-Barranco, Ana M; de Los Reyes-Gavilán, Clara G; Gueimonde, Miguel

    2016-07-01

    A better understanding of the interactions among intestinal microbes is needed to decipher the complex cross talk that takes place within the human gut. Bacteroides and Bifidobacterium genera are among the most relevant intestinal bacteria, and it has been previously reported that coculturing of these 2 microorganisms affects their survival. Therefore, coculturing of Bifidobacterium longum NB667 and Bacteroides fragilis DSMZ2151 was performed with the aim of unravelling the mechanisms involved in their interaction. To this end, we applied proteomic (2D-DIGE) analyses, and by chromatographic techniques we quantified the bacterial metabolites produced during coincubation. Coculture stimulated the growth of B. longum, retarding that of B. fragilis, with concomitant changes in the production of some proteins and metabolites of both bacteria. The combined culture promoted upregulation of the bifidobacterial pyruvate kinase and downregulation of the Bacteroides phosphoenolpyruvate carboxykinase - 2 enzymes involved in the catabolism of carbohydrates. Moreover, B. fragilis FKBP-type peptidyl-prolyl cis-trans isomerase, a protein with chaperone-like activity, was found to be overproduced in coculture, suggesting the induction of a stress response in this microorganism. This study provides mechanistic data to deepen our understanding of the interaction between Bacteroides and Bifidobacterium intestinal populations. PMID:27156738

  14. Involvement of glutamate in the respiratory metabolism of Bradyrhizobium japonicum bacteroids.

    PubMed

    Salminen, S O; Streeter, J G

    1987-02-01

    Bradyrhizobium japonicum bacteroids were isolated anaerobically and supplied with 14C-labeled succinate, malate, aspartate, or glutamate for periods of up to 60 min in the presence of myoglobin to control the O2 concentration. Succinate and malate were absorbed about twice as rapidly as glutamate and aspartate. Conversion of substrate to CO2 was most rapid for malate, followed by succinate, glutamate, and aspartate. When CO2 production was expressed as a proportion of total carbon taken up, malate was still the most rapidly respired substrate, with 68% of the label absorbed converted to CO2. The comparable values for succinate, glutamate, and aspartate were 37, 50, and 38%, respectively. Considering the fate of labeled substrate not respired, greater than 95% of absorbed glutamate remained as glutamate in the bacteroids. In contrast, from 39 to 66% of the absorbed succinate, malate, or aspartate was converted to glutamate. An increase in the rate of CO2 formation from labeled substrates after 20 min appeared to coincide with a maximum accumulation of label in glutamate. The results indicate the presence of a substantial glutamate pool in bacteroids and the involvement of glutamate in the respiratory metabolism of bacteroids. PMID:2879829

  15. Multidrug-Resistant Bacteroides fragilis Bacteremia in a US Resident: An Emerging Challenge

    PubMed Central

    Parajuli, Sunita; Siegfried, Justin; Dubrovskaya, Yanina; Rahimian, Joseph

    2016-01-01

    We describe a case of Bacteroides fragilis bacteremia associated with paraspinal and psoas abscesses in the United States. Resistance to b-lactam/b-lactamase inhibitors, carbapenems, and metronidazole was encountered despite having a recent travel history to India as the only possible risk factor for multidrug resistance. Microbiological cure was achieved with linezolid, moxifloxacin, and cefoxitin. PMID:27418986

  16. Effect of salt stress on glycine betaine biosynthesis and catabolism by Medicago sativa bacteroids

    SciTech Connect

    Fougere, F.; Poggi, M.-C.; Le Rudulier, D. )

    1990-05-01

    Previous works have shown that glycine betaine (GB) and choline (Cho) are actively taken up by Medicago sativa bacteroids isolated from 4-week-old nodules. Here, we have investigated the effects of NaCl on the fte of Cho and GB. Bacteroids were incubated in low- or high-salt-medium (0.4 M NaCl) and supplemented with {sup 14}C 1,2-Cho or {sup 14}C 1,2-GB. After 3 hours, radioactivity was measured in CO{sub 2} released, in ethanol-soluble and insoluble fractions. In absence of salt, a low proportion of the labelling was found in soluble fraction: 47 and 19% after Cho or GB supply, respectively. On the contrary, in high-salt-medium, the soluble fraction still contained 85% of the radioactivity with GB corresponding to 92-98%. Both enzymes involved in GB biosynthesis from Cho were studied. Choline oxidase activity was enhanced by 59%, while betainal dehydrogenase activity remained unchanged after bacteroid incubation in high-salt-medium. Thus, GB accumulation in salt-stressed bacteroids would be likely a consequence of a decrease of its catabolism rather than an increase of its biosynthesis.

  17. Bacteroides isolated from four mammalian hosts lack host specific patterns in carbon and nitrogen metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Within the distal gut of mammals are found trillions of microbes that utilize nutrients from diet, intestinal mucosa, and other gut microbes. 402 isolates of Bacteroides ovatus, B. thetaiotaomicron, and B. xylanisolvens were recovered from cow, goat, human, and pig fecal enrichments with cellulose o...

  18. Near-complete genome sequence of the cellulolytic Bacterium Bacteroides (Pseudobacteroides) cellulosolvens ATCC 35603

    DOE PAGESBeta

    Dassa, Bareket; Utturkar, Sagar M.; Hurt, Richard A.; Klingeman, Dawn Marie; Keller, Martin; Xu, Jian; Reddy, Harish Kumar; Borovok, Ilya; Grinberg, Inna Rozman; Lamed, Raphael; et al

    2015-09-24

    We report the single-contig genome sequence of the anaerobic, mesophilic, cellulolytic bacterium, Bacteroides cellulosolvens. The bacterium produces a particularly elaborate cellulosome system, whereas the types of cohesin-dockerin interactions are opposite of other known cellulosome systems: cell-surface attachment is thus mediated via type-I interactions whereas enzymes are integrated via type-II interactions.

  19. Biosynthesis of Rhizobium meliloti lipooligosaccharide Nod factors: NodA is required for an N-acyltransferase activity

    SciTech Connect

    Atkinson, E.M.; Long, S.R. ); Palcic, M.M.; Hindsgaul, O. )

    1994-08-30

    Rhizobium bacteria synthesize N-acylated [beta]-1,4-N-acetylglucosamine lipooligosaccharides, called Nod factors, which act as morphogenic signal molecules to legume roots during development of nitrogen-fixing nodules. The biosynthesis of Nod factors is genetically dependent upon the nodulation (nod) genes, including the common nod genes nodABC. We used the Rhizobium meliloti NodH sulfotransferase to prepare [sup 35]S-labeled oligosaccharides which served as metabolic tracers for Nod enzyme activities. This approach provides a general method for following chitooligosaccharide modifications. We found nodAB-dependent conversion of N-acetylchitotetraose (chitotetraose) monosulfate into hydrophobic compounds which by chromatographic and chemical tests were equivalent to acylated Nod factors. Sequential incubation of labeled intermediates with Escherichia coli containing either NodA or NodB showed that NodB was required before NodA during Nod factor biosynthesis. The acylation activity was sensitive to oligosaccharide chain length, with chitotetraose serving as a better substrate than chitobiose or chitotriose. We constructed a putative Nod factor intermediate, GlcN-[beta]1,4-(GlcNac)[sub 3], by enzymatic synthesis and labeled it by NodH-mediated sulfation to create a specific metabolic probe. Acylation of this oligosaccharide required only NodA. These results confirm previous reports that NodB is an N-deacetylase and suggest that NodA is an N-acyltransferase. 31 refs., 6 figs.

  20. Alfalfa yield response to inoculation with recombinant strains of Rhizobium meliloti with an extra copy of dctABD and/or modified nifA expression.

    PubMed

    Bosworth, A H; Williams, M K; Albrecht, K A; Kwiatkowski, R; Beynon, J; Hankinson, T R; Ronson, C W; Cannon, F; Wacek, T J; Triplett, E W

    1994-10-01

    The construction of rhizobial strains which increase plant biomass under controlled conditions has been previously reported. However, there is no evidence that these newly constructed strains increase legume yield under agricultural conditions. This work tested the hypothesis that carefully manipulating expression of additional copies of nifA and dctABD in strains of Rhizobium meliloti would increase alfalfa yield in the field. The rationale for this hypothesis is based on the positive regulatory role that nifA plays in the expression of the nif regulon and the fact that a supply of dicarboxylic acids from the plant is required as a carbon and energy source for nitrogen fixation by the Rhizobium bacteroids in the nodule. These recombinant strains, as well as the wild-type strains from which they were derived, are ideal tools to examine the effects of modifying or increasing the expression of these genes on alfalfa biomass. The experimental design comprised seven recombinant strains, two wild-type strains, and an uninoculated control. Each treatment was replicated eight times and was conducted at four field sites in Wisconsin. Recombinant strain RMBPC-2, which has an additional copy of both nifA and dctABD, increased alfalfa biomass by 12.9% compared with the yield with the wild-type strain RMBPC and 17.9% over that in the uninoculated control plot at the site where soil nitrogen and organic matter content was lowest. These increases were statistically significant at the 5% confidence interval for each of the three harvests made during the growing season. Strain RMBPC-2 did increase alfalfa biomass at the Hancock site; however, no other significant increases or decreases in alfalfa biomass were observed with the seven other recombinant strains at that site. At three sites where this experiment was conducted, either native rhizobial populations or soil nitrogen concentrations were high. At these sites, none of the recombinant strains affected yield. We conclude that

  1. Bacteroides paurosaccharolyticus sp. nov., isolated from a methanogenic reactor treating waste from cattle farms.

    PubMed

    Ueki, Atsuko; Abe, Kunihiro; Ohtaki, Yoshimi; Kaku, Nobuo; Watanabe, Kazuya; Ueki, Katsuji

    2011-02-01

    A strictly anaerobic bacterial strain (WK042(T)) was isolated from rice-straw residue in a methanogenic reactor treating waste from cattle farms in Japan. Cells were Gram-staining-negative, non-motile, non-spore-forming rods. Growth was stimulated well by haemin, and was enhanced by cobalamin (vitamin B(12)). Strain WK042(T) utilized arabinose, xylose, glucose, mannose and aesculin as preferred substrates. Maltose, dextrin, glycogen, starch and pectin were also utilized, although growth on these substrates was much slower. The strain produced acetate, propionate and succinate from these saccharides. The strain was slightly alkaliphilic, with optimum growth at pH 7.7. The temperature range for growth was 10-40 °C, the optimum being 35 °C. The strain was sensitive to bile. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(17 : 0) 3-OH and C(15 : 0). Menaquinone 11 (MK-11) was the major respiratory quinone and the genomic DNA G+C content was 41.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences placed the strain in the phylum Bacteroidetes. Strain WK042(T) was related distantly to the type strains of species in the cluster including Bacteroides massiliensis, Bacteroides vulgatus and Bacteroides dorei (91-92 % 16S rRNA gene sequence similarity). Based on data from the present phylogenetic, physiological and chemotaxonomic analyses, strain WK042(T) is considered to represent a novel species of the genus Bacteroides, for which the name Bacteroides paurosaccharolyticus sp. nov. is proposed. The type strain is WK042(T) (=JCM 15092(T) =DSM 21004(T)). PMID:20348319

  2. The Regulatory Protein RosR Affects Rhizobium leguminosarum bv. trifolii Protein Profiles, Cell Surface Properties, and Symbiosis with Clover.

    PubMed

    Rachwał, Kamila; Boguszewska, Aleksandra; Kopcińska, Joanna; Karaś, Magdalena; Tchórzewski, Marek; Janczarek, Monika

    2016-01-01

    Rhizobium leguminosarum bv. trifolii is capable of establishing a symbiotic relationship with plants from the genus Trifolium. Previously, a regulatory protein encoded by rosR was identified and characterized in this bacterium. RosR possesses a Cys2-His2-type zinc finger motif and belongs to Ros/MucR family of rhizobial transcriptional regulators. Transcriptome profiling of the rosR mutant revealed a role of this protein in several cellular processes, including the synthesis of cell-surface components and polysaccharides, motility, and bacterial metabolism. Here, we show that a mutation in rosR resulted in considerable changes in R. leguminosarum bv. trifolii protein profiles. Extracellular, membrane, and periplasmic protein profiles of R. leguminosarum bv. trifolii wild type and the rosR mutant were examined, and proteins with substantially different abundances between these strains were identified. Compared with the wild type, extracellular fraction of the rosR mutant contained greater amounts of several proteins, including Ca(2+)-binding cadherin-like proteins, a RTX-like protein, autoaggregation protein RapA1, and flagellins FlaA and FlaB. In contrast, several proteins involved in the uptake of various substrates were less abundant in the mutant strain (DppA, BraC, and SfuA). In addition, differences were observed in membrane proteins of the mutant and wild-type strains, which mainly concerned various transport system components. Using atomic force microscopy (AFM) imaging, we characterized the topography and surface properties of the rosR mutant and wild-type cells. We found that the mutation in rosR gene also affected surface properties of R. leguminosarum bv. trifolii. The mutant cells were significantly more hydrophobic than the wild-type cells, and their outer membrane was three times more permeable to the hydrophobic dye N-phenyl-1-naphthylamine. The mutation of rosR also caused defects in bacterial symbiotic interaction with clover plants. Compared with

  3. The Regulatory Protein RosR Affects Rhizobium leguminosarum bv. trifolii Protein Profiles, Cell Surface Properties, and Symbiosis with Clover

    PubMed Central

    Rachwał, Kamila; Boguszewska, Aleksandra; Kopcińska, Joanna; Karaś, Magdalena; Tchórzewski, Marek; Janczarek, Monika

    2016-01-01

    Rhizobium leguminosarum bv. trifolii is capable of establishing a symbiotic relationship with plants from the genus Trifolium. Previously, a regulatory protein encoded by rosR was identified and characterized in this bacterium. RosR possesses a Cys2-His2-type zinc finger motif and belongs to Ros/MucR family of rhizobial transcriptional regulators. Transcriptome profiling of the rosR mutant revealed a role of this protein in several cellular processes, including the synthesis of cell-surface components and polysaccharides, motility, and bacterial metabolism. Here, we show that a mutation in rosR resulted in considerable changes in R. leguminosarum bv. trifolii protein profiles. Extracellular, membrane, and periplasmic protein profiles of R. leguminosarum bv. trifolii wild type and the rosR mutant were examined, and proteins with substantially different abundances between these strains were identified. Compared with the wild type, extracellular fraction of the rosR mutant contained greater amounts of several proteins, including Ca2+-binding cadherin-like proteins, a RTX-like protein, autoaggregation protein RapA1, and flagellins FlaA and FlaB. In contrast, several proteins involved in the uptake of various substrates were less abundant in the mutant strain (DppA, BraC, and SfuA). In addition, differences were observed in membrane proteins of the mutant and wild-type strains, which mainly concerned various transport system components. Using atomic force microscopy (AFM) imaging, we characterized the topography and surface properties of the rosR mutant and wild-type cells. We found that the mutation in rosR gene also affected surface properties of R. leguminosarum bv. trifolii. The mutant cells were significantly more hydrophobic than the wild-type cells, and their outer membrane was three times more permeable to the hydrophobic dye N-phenyl-1-naphthylamine. The mutation of rosR also caused defects in bacterial symbiotic interaction with clover plants. Compared with

  4. Non-contiguous finished genome sequence and description of Bacteroides neonati sp. nov., a new species of anaerobic bacterium

    PubMed Central

    Cassir, Nadim; Croce, Olivier; Pagnier, Isabelle; Benamar, Samia; Couderc, Carine; Robert, Catherine; Raoult, Didier; La Scola, Bernard

    2014-01-01

    Bacteroides neonati strain MS4T, is the type strain of Bacteroides neonati sp. nov., a new species within the genus Bacteroides. This strain, whose genome is described here, was isolated from a premature neonate stool sample. B. neonati strain MS4T is an obligate anaerobic Gram-negative bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 5.03 Mbp long genome exhibits a G+C content of 43.53% and contains 4,415 protein-coding and 91 RNA genes, including 9 rRNA genes. PMID:25197464

  5. Metallo-β-Lactamase-Producing Bacteroides Species Can Shield Other Members of the Gut Microbiota from Antibiotics

    PubMed Central

    Tima, Mary Ann; Nerandzic, Michelle M.

    2014-01-01

    Antibiotics disrupt the intestinal microbiota, rendering patients vulnerable to colonization by exogenous pathogens. Intermicrobial interactions may attenuate this effect. Incubation with ceftriaxone-resistant, ccrA-positive, β-lactamase-producing Bacteroides strains raised the minimum bactericidal concentration of ceftriaxone required to kill a susceptible Escherichia coli strain (mean change, <0.25 to 29 mg/liter; P = 0.009); incubation with ceftriaxone-resistant but non-β-lactamase-producing Bacteroides strains had no effect. The production of β-lactamase by common members of the intestinal microbiota (Bacteroides) can protect susceptible fellow commensals from β-lactams. PMID:25288080

  6. Rhizobium taibaishanense sp. nov., isolated from a root nodule of Kummerowia striata.

    PubMed

    Yao, Li Juan; Shen, Yao Yao; Zhan, Jun Peng; Xu, Wei; Cui, Guang Ling; Wei, Ge Hong

    2012-02-01

    During a study of the diversity and phylogeny of rhizobia in the root nodules of Kummerowia striata grown in north-western China, four strains were classified in the genus Rhizobium on the basis of their 16S rRNA gene sequences. The 16S rRNA gene sequences of three of these strains were identical and that of the other strain, which was the only one isolated in Yangling, differed from the others by just 1 bp. The16S rRNA gene sequences of the four strains showed a mean similarity of 99.3 % with the most closely related, recognized species, Rhizobium vitis. The corresponding recA and glnA gene sequences showed similarities with established species of Rhizobium of less than 86.5 % and less than 89.6 %, respectively. These low similarities indicated that the four strains represented a novel species of the genus Rhizobium. The strains were also found to be distinguishable from the closest related, established species (R. vitis) by rep-PCR DNA fingerprinting, analysis of cellular fatty acid profiles and from the results of a series of phenotypic tests. The level of DNA-DNA relatedness between the representative strain CCNWSX 0483(T) and Rhizobium vitis IAM 14140(T) was only 40.13 %. Therefore, a novel species, Rhizobium taibaishanense sp. nov., is proposed, with strain CCNWSX 0483(T) ( = ACCC 14971(T) = HAMBI 3214(T)) as the type strain. In nodulation and pathogenicity tests, none of the four strains of Rhizobium taibaishanense sp. nov. was able to induce any nodule or tumour formation on plants. As no amplicons were detected when DNA from the strains was run in PCR with primers for the detection of nodA, nifH and virC gene sequences, the strains probably do not carry sym or vir genes. PMID:21421926

  7. Characterization of enterotoxigenic Bacteroides fragilis by a toxin-specific enzyme-linked immunosorbent assay.

    PubMed Central

    Van Tassell, R L; Lyerly, D M; Wilkins, T D

    1994-01-01

    Within the past decade, certain strains of Bacteroides fragilis have been associated with diarrhea in humans and cytotoxic activity on certain colon carcinoma cell lines. An enzyme-linked immunosorbent assay (ELISA) for detecting the enterotoxin of B. fragilis in cultures and stools was developed by using high-titer monospecific goat and rabbit antitoxins in an indirect format. The lower limit of detection for purified toxin was approximately 0.05 micrograms/ml; the linear range was from 0.05 to 10 microgram/ml. Using the ELISA to screen cultures of toxigenic and nontoxigenic strains of B. fragilis, we observed 100% correlation with 16 known toxigenic strains which had various cytotoxic activities on HT-29 cells. In addition, we found 6 of 62 previously untested strains also to be positive in both assays. Stability studies revealed that although the cytotoxic activities of crude and purified toxin preparations incubated at elevated temperatures were rapidly lost, the ELISA responses were not significantly reduced. Sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis and SDS-capillary electrophoresis showed that the purified toxin autodigested to several stable peptides. Studies on partially purified membranes from the toxigenic strains revealed the presence of several membrane-associated components which were noncytotoxic but strongly immunoreactive in the ELISA. Preliminary studies with spiked feces indicated that the ELISA may be useful for screening not only cultures for the enterotoxigenic B. fragilis but also stool specimens. Ongoing studies are focusing on determining the nature of the toxin's apparent proteolytic capabilities and investigating the feasibility of using the ELISA on stool specimens from healthy and diarrheic humans. Images PMID:8556504

  8. Nitrogen-fixing Rhizobium-legume symbiosis: are polyploidy and host peptide-governed symbiont differentiation general principles of endosymbiosis?

    PubMed Central

    Maróti, Gergely; Kondorosi, Éva

    2014-01-01

    The symbiosis between rhizobia soil bacteria and legumes is facultative and initiated by nitrogen starvation of the host plant. Exchange of signal molecules between the partners leads to the formation of root nodules where bacteria are converted to nitrogen-fixing bacteroids. In this mutualistic symbiosis, the bacteria provide nitrogen sources for plant growth in return for photosynthates from the host. Depending on the host plant the symbiotic fate of bacteria can either be reversible or irreversible. In Medicago plants the bacteria undergo a host-directed multistep differentiation process culminating in the formation of elongated and branched polyploid bacteria with definitive loss of cell division ability. The plant factors are nodule-specific symbiotic peptides. About 500 of them are cysteine-rich NCR peptides produced in the infected plant cells. NCRs are targeted to the endosymbionts and the concerted action of different sets of peptides governs different stages of endosymbiont maturation. This review focuses on symbiotic plant cell development and terminal bacteroid differentiation and demonstrates the crucial roles of symbiotic peptides by showing an example of multi-target mechanism exerted by one of these symbiotic peptides. PMID:25071739

  9. Nodules Initiated by Rhizobium meliloti Exopolysaccharide Mutants Lack a Discrete, Persistent Nodule Meristem 1

    PubMed Central

    Yang, Cheng; Signer, Ethan R.; Hirsch, Ann M.

    1992-01-01

    Infection of alfalfa with Rhizobium meliloti exo mutants deficient in exopolysaccharide results in abnormal root nodules that are devoid of bacteria and fail to fix nitrogen. Here we report further characterization of these abnormal nodules. Tightly curled root hairs or shepherd's crooks were found after inoculation with Rm 1021-derived exo mutants, but curling was delayed compared with wild-type Rm 1021. Infection threads were initiated in curled root hairs by mutants as well as by wild-type R. meliloti, but the exo mutant-induced threads aborted within the peripheral cells of the developing nodule. Also, nodules elicited by Rm 1021-derived exo mutants were more likely to develop on secondary roots than on the primary root. In contrast with wild-type R. meliloti-induced nodules, the exo mutant-induced nodules lacked a well defined apical meristem, presumably due to the abortion of the infection threads. The relationship of these findings to the physiology of nodule development is discussed. ImagesFigure 3Figure 1Figure 2Figure 4 PMID:16668605

  10. Rhizobium cellulase CelC2 is essential for primary symbiotic infection of legume host roots

    PubMed Central

    Robledo, M.; Jiménez-Zurdo, J. I.; Velázquez, E.; Trujillo, M. E.; Zurdo-Piñeiro, J. L.; Ramírez-Bahena, M. H.; Ramos, B.; Díaz-Mínguez, J. M.; Dazzo, F.; Martínez-Molina, E.; Mateos, P. F.

    2008-01-01

    The rhizobia–legume, root-nodule symbiosis provides the most efficient source of biologically fixed ammonia fertilizer for agricultural crops. Its development involves pathways of specificity, infectivity, and effectivity resulting from expressed traits of the bacterium and host plant. A key event of the infection process required for development of this root-nodule symbiosis is a highly localized, complete erosion of the plant cell wall through which the bacterial symbiont penetrates to establish a nitrogen-fixing, intracellular endosymbiotic state within the host. This process of wall degradation must be delicately balanced to avoid lysis and destruction of the host cell. Here, we describe the purification, biochemical characterization, molecular genetic analysis, biological activity, and symbiotic function of a cell-bound bacterial cellulase (CelC2) enzyme from Rhizobium leguminosarum bv. trifolii, the clover-nodulating endosymbiont. The purified enzyme can erode the noncrystalline tip of the white clover host root hair wall, making a localized hole of sufficient size to allow wild-type microsymbiont penetration. This CelC2 enzyme is not active on root hairs of the nonhost legume alfalfa. Microscopy analysis of the symbiotic phenotypes of the ANU843 wild type and CelC2 knockout mutant derivative revealed that this enzyme fulfils an essential role in the primary infection process required for development of the canonical nitrogen-fixing R. leguminosarum bv. trifolii-white clover symbiosis. PMID:18458328

  11. Enhanced nitrogen fixation in a Rhizobium etli ntrC mutant that overproduces the Bradyrhizobium japonicum symbiotic terminal oxidase cbb{sub 3}

    SciTech Connect

    Soberon, M.; Lopez, O.; Morera, C.; Girard, M.L.; Tabche, M.L.; Miranda, J.

    1999-05-01

    The ntrC gene codes for a transcriptional activator protein that modulates gene expression in response to nitrogen. The cytochrome production pattern of a Rhizobium etli ntrC mutant (CFN2012) was studied. CO difference spectral analysis of membranes showed that CFN2012 produced a terminal oxidase similar to the symbiotic terminal oxidase of bacteroids in free-living cells under aerobic conditions, with a characteristic trough at 553 nm. CFN2012 produced two c-type cytochromes with molecular masses of 27 and 32 kDa in contrast with the wild-type strain, which produced only a 32-kDa c-tye cytochrome. The expression levels of the R. etli fix/NOQP operon, which codes for terminal oxidase cbb{sub 3}, were not affected by the ntrC mutation. However, the production levels of the two c-type cytochromes (27 and 32 kDa) were enhanced at least eightfold when the Bradyrhizobium japonicum fixNOQP operon was expressed in CFN2012 from the nptII promoter (pMSfix{sup c}), suggesting that these proteins are subunits FixO (27 kDa) and FixP (32 kDa) of cbb{sub 3} and that CFN2012/pMSfix{sup c} overproduced this terminal oxidase. CFN2012/pMSfix{sup c} showed a significant increase in its symbiotic performance as judged by the determination of nitrogenase activities of plants inoculated with this strain, suggesting that the overproduction of cbb{sub 3} terminal oxidase correlates with an enhancement in symbiotic nitrogen fixation.

  12. Maturation of Rhizobium leguminosarum Hydrogenase in the Presence of Oxygen Requires the Interaction of the Chaperone HypC and the Scaffolding Protein HupK*

    PubMed Central

    Albareda, Marta; Pacios, Luis F.; Manyani, Hamid; Rey, Luis; Brito, Belén; Imperial, Juan; Ruiz-Argüeso, Tomás; Palacios, Jose M.

    2014-01-01

    [NiFe] hydrogenases are key enzymes for the energy and redox metabolisms of different microorganisms. Synthesis of these metalloenzymes involves a complex series of biochemical reactions catalyzed by a plethora of accessory proteins, many of them required to synthesize and insert the unique NiFe(CN)2CO cofactor. HypC is an accessory protein conserved in all [NiFe] hydrogenase systems and involved in the synthesis and transfer of the Fe(CN)2CO cofactor precursor. Hydrogenase accessory proteins from bacteria-synthesizing hydrogenase in the presence of oxygen include HupK, a scaffolding protein with a moderate sequence similarity to the hydrogenase large subunit and proposed to participate as an intermediate chaperone in the synthesis of the NiFe cofactor. The endosymbiotic bacterium Rhizobium leguminosarum contains a single hydrogenase system that can be expressed under two different physiological conditions: free-living microaerobic cells (∼12 μm O2) and bacteroids from legume nodules (∼10–100 nm O2). We have used bioinformatic tools to model HupK structure and interaction of this protein with HypC. Site-directed mutagenesis at positions predicted as critical by the structural analysis have allowed the identification of HupK and HypC residues relevant for the maturation of hydrogenase. Mutant proteins altered in some of these residues show a different phenotype depending on the physiological condition tested. Modeling of HypC also predicts the existence of a stable HypC dimer whose presence was also demonstrated by immunoblot analysis. This study widens our understanding on the mechanisms for metalloenzyme biosynthesis in the presence of oxygen. PMID:24942742

  13. Rhizobium grahamii sp. nov., from nodules of Dalea leporina, Leucaena leucocephala and Clitoria ternatea, and Rhizobium mesoamericanum sp. nov., from nodules of Phaseolus vulgaris, siratro, cowpea and Mimosa pudica.

    PubMed

    López-López, Aline; Rogel-Hernández, Marco A; Barois, Isabelle; Ortiz Ceballos, Angel I; Martínez, Julio; Ormeño-Orrillo, Ernesto; Martínez-Romero, Esperanza

    2012-09-01

    Two novel related Rhizobium species, Rhizobium grahamii sp. nov. and Rhizobium mesoamericanum sp. nov., were identified by a polyphasic approach using DNA-DNA hybridization, whole-genome sequencing and phylogenetic and phenotypic characterization including nodulation of Leucaena leucocephala and Phaseolus vulgaris (bean). As similar bacteria were found in the Los Tuxtlas rainforest in Mexico and in Central America, we suggest the existence of a Mesoamerican microbiological corridor. The type strain of Rhizobium grahamii sp. nov. is CCGE 502(T) (= ATCC BAA-2124(T) = CFN 242(T) = Dal4(T) = HAMBI 3152(T)) and that of Rhizobium mesoamericanum sp. nov. is CCGE 501(T) (= ATCC BAA-2123(T) = HAMBI 3151(T) = CIP 110148(T) = 1847(T)). PMID:22081714

  14. Rhizobium sp. strain BN4 (a selenium oxyanion-reducing bacterium) 16S rRNA gene complete sequence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study used 1482 base pair 16S rRNA gene sequence methods in conjunction with other biochemical and morphological studies to confirm the identification of a bacterium (refer to as the BN4 strain) as a Rhizobium sp. The 16S rRNA gene sequence places it with the Rhizobium clade that includes R. d...

  15. Rhizobium oryzicola sp. nov., potential plant-growth-promoting endophytic bacteria isolated from rice roots.

    PubMed

    Zhang, Xiao-Xia; Gao, Ju-Sheng; Cao, Yan-Hua; Sheirdil, Rizwan Ali; Wang, Xiu-Cheng; Zhang, Lei

    2015-09-01

    Bacterial strains ZYY136(T) and ZYY9 were isolated from surface-sterilized rice roots from a long-term experiment of rice-rice--Astragalus sinicus rotation. The 16S rRNA gene sequences of strains ZYY136(T) and ZYY9 showed the highest similarity, of 97.0%, to Rhizobium tarimense PL-41(T). Sequence analysis of the housekeeping genes recA, thrC and atpD clearly differentiated the isolates from currently described species of the genus Rhizobium. The DNA-DNA relatedness value between ZYY136(T) and ZYY9 was 82.3%, and ZYY136(T) showed 34.0% DNA-DNA relatedness with the most closely related type strain, R. tarimense PL-41(T). The DNA G+C content of strain ZYY136(T) was 58.1 mol%. The major cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C16 : 0 and C16 : 0 3-OH. Strains ZYY136(T) and ZYY9 could be differentiated from the previously defined species of the genus Rhizobium by several phenotypic characteristics. Therefore, we conclude that strains ZYY136(T) and ZYY9 represent a novel species of the genus Rhizobium, for which the name Rhizobium oryzicola sp. nov. is proposed (type strain ZYY136(T) = ACCC 05753(T) = KCTC 32088(T)). PMID:26016492

  16. Characterization of the N2O-producing soil bacterium Rhizobium azooxidifex sp. nov.

    PubMed

    Behrendt, Undine; Kämpfer, Peter; Glaeser, Stefanie P; Augustin, Jürgen; Ulrich, Andreas

    2016-06-01

    In the context of studying the bacterial community involved in nitrogen transformation processes in arable soils exposed to different extents of erosion and sedimentation in a long-term experiment (CarboZALF), a strain was isolated that reduced nitrate to nitrous oxide without formation of molecular nitrogen. The presence of the functional gene nirK, encoding the respiratory copper-containing nitrite reductase, and the absence of the nitrous oxide reductase gene nosZ indicated a truncated denitrification pathway and that this bacterium may contribute significantly to the formation of the important greenhouse gas N2O. Phylogenetic analysis based on the 16S rRNA gene sequence and the housekeeping genes recA and atpD demonstrated that the investigated soil isolate belongs to the genus Rhizobium. The closest phylogenetic neighbours were the type strains of Rhizobium. subbaraonis and Rhizobium. halophytocola. The close relationship with R. subbaraonis was reflected by similarity analysis of the recA and atpD genes and their amino acid positions. DNA-DNA hybridization studies revealed genetic differences at the species level, which were substantiated by analysis of the whole-cell fatty acid profile and several distinct physiological characteristics. Based on these results, it was concluded that the soil isolate represents a novel species of the genus Rhizobium, for which the name Rhizobium azooxidifex sp. nov. (type strain Po 20/26T=DSM 100211T=LMG 28788T) is proposed. PMID:27030972

  17. The structure of legume-rhizobium interaction networks and their response to tree invasions.

    PubMed

    Le Roux, Johannes J; Mavengere, Natasha R; Ellis, Allan G

    2016-01-01

    Establishing mutualistic interactions in novel environments is important for the successful establishment of some non-native plant species. These associations may, in turn, impact native species interaction networks as non-natives become dominant in their new environments. Using phylogenetic and ecological interaction network approaches we provide the first report of the structure of belowground legume-rhizobium interaction networks and how they change along a gradient of invasion (uninvaded, semi invaded and heavily invaded sites) by Australian Acacia species in South Africa's Cape Floristic Region. We found that native and invasive legumes interact with distinct rhizobial lineages, most likely due to phylogenetic uniqueness of native and invasive host plants. Moreover, legume-rhizobium interaction networks are not nested, but significantly modular with high levels of specialization possibly as a result of legume-rhizobium co-evolution. Although network topology remained constant across the invasion gradient, composition of bacterial communities associated with native legumes changed dramatically as acacias increasingly dominated the landscape. In stark contrast to aboveground interaction networks (e.g. pollination and seed dispersal) we show that invasive legumes do not infiltrate existing native legume-rhizobium networks but rather form novel modules. This absence of mutualist overlap between native and invasive legumes suggests the importance of co-invading rhizobium-acacia species complexes for Acacia invasion success, and argues against a ubiquitous role for the formation and evolutionary refinement of novel interactions. PMID:27255514

  18. Two host-inducible genes of Rhizobium fredii and characterization of the inducing compound.

    PubMed Central

    Sadowsky, M J; Olson, E R; Foster, V E; Kosslak, R M; Verma, D P

    1988-01-01

    Random transcription fusions with Mu d1(Kan lac) generated three mutants in Rhizobium fredii (strain USDA 201) which showed induction of beta-galactosidase when grown in root exudate of the host plants Glycine max, Phaseolus vulgaris, and Vigna ungliculata. Two genes were isolated from a library of total plasmid DNA of one of the mutants, 3F1. These genes, present in tandem on a 4.2-kilobase HindIII fragment, appear in one copy each on the symbiotic plasmid and do not hybridize to the Rhizobium meliloti common nodulation region. They comprise two separate transcriptional units coding for about 450 and 950 nucleotides, both of which are transcribed in the same direction. The two open reading frames are separated by 586 base pairs, and the 5H regions of the two genes show a common sequence. No similarity was found with the promoter areas of Rhizobium trifolii, R. meliloti, or Bradyrhizobium japonicum nif genes and with any known nodulation genes. Regions homologous to both sequences were detected in EcoRI digests of genomic DNAs from B. japonicum USDA 110, USDA 122, and 61A76, but not in genomic DNA from R. trifolii, Rhizobium leguminosarum, or Rhizobium phaseoli. Mass spectrometry and nuclear magnetic resonance analysis indicated that the inducing compound has properties of 4',7-dihydroxyisoflavone, daidzein. These results suggest that, in addition to common nodulation genes, several other genes appear to be specifically induced by compounds in the root exudate of the host plants. Images PMID:2447061

  19. Mapping the Genetic Basis of Symbiotic Variation in Legume-Rhizobium Interactions in Medicago truncatula

    PubMed Central

    Gorton, Amanda J.; Heath, Katy D.; Pilet-Nayel, Marie-Laure; Baranger, Alain

    2012-01-01

    Mutualisms are known to be genetically variable, where the genotypes differ in the fitness benefits they gain from the interaction. To date, little is known about the loci that underlie such genetic variation in fitness or whether the loci influencing fitness are partner specific, and depend on the genotype of the interaction partner. In the legume-rhizobium mutualism, one set of potential candidate genes that may influence the fitness benefits of the symbiosis are the plant genes involved in the initiation of the signaling pathway between the two partners. Here we performed quantitative trait loci (QTL) mapping in Medicago truncatula in two different rhizobium strain treatments to locate regions of the genome influencing plant traits, assess whether such regions are dependent on the genotype of the rhizobial mutualist (QTL × rhizobium strain), and evaluate the contribution of sequence variation at known symbiosis signaling genes. Two of the symbiotic signaling genes, NFP and DMI3, colocalized with two QTL affecting average fruit weight and leaf number, suggesting that natural variation in nodulation genes may potentially influence plant fitness. In both rhizobium strain treatments, there were QTL that influenced multiple traits, indicative of either tight linkage between loci or pleiotropy, including one QTL with opposing effects on growth and reproduction. There was no evidence for QTL × rhizobium strain or genotype × genotype interactions, suggesting either that such interactions are due to small-effect loci or that more genotype-genotype combinations need to be tested in future mapping studies. PMID:23173081

  20. Marsh soils as potential sinks for Bacteroides fecal indicator bacteria, Waccamaw National Wildlife Refuge, Georgetown, SC, USA

    USGS Publications Warehouse

    Drexler, Judith Z.; Johnson, Heather E.; Duris, Joseph W.; Krauss, Ken W.

    2014-01-01

    A soil core collected in a tidal freshwater marsh in the Waccamaw National Wildlife Refuge (Georgetown, SC) exuded a particularly strong odor of cow manure upon extrusion. In order to test for manure and determine its provenance, we carried out microbial source tracking using DNA markers for Bacteroides, a noncoliform, anaerobic bacterial group that represents a broad group of the fecal population. Three core sections from 0-3 cm, 9-12 cm and 30-33 were analyzed for the presence of Bacteroides. The ages of core sediments were estimated using 210Pb and 137Cs dating. All three core sections tested positive for Bacteroides DNA markers related to cow or deer feces. Because cow manure is stockpiled, used as fertilizer, and a source of direct contamination in the Great Pee Dee River/Winyah Bay watershed, it is very likely the source of the Bacteroides that was deposited on the marsh. The mid-points of the core sections were dated as follows: 0-3 cm: 2009; 9-12 cm: 1999, and 30-33 cm: 1961. The presence of Bacteroides at different depths/ages in the soil profile indicates that soils in tidal freshwater marshes are, at the least, capable of being short-term sinks for Bacteroides and, may have the potential to be long-term sinks of stable, naturalized populations.

  1. Inhibition of ribonucleic acid polymerase by a bacteriocin from Bacteroides fragilis.

    PubMed Central

    Mossie, K G; Robb, F T; Jones, D T; Woods, D R

    1981-01-01

    The Bacteroides fragilis bacteriocin which inhibits ribonucleic acid (RNA) polymerase activity had a narrow activity spectrum in vivo and only inhibited the growth of certain B. fragilis strains. In vitro the bacteriocin was not specific and inhibited RNA polymerases from widely diverse bacterial genera. RNA polymerases from rifampin-resistant strains of Bacteroides thetaiotaomicron and Clostridium acetobutylicum were resistant to the bacteriocin in vitro. Purified bacteriocin bound to partially purified RNA polymerase, and both proteins were cosedimented in a glycerol gradient. In the RNA polymerase reaction, the bacteriocin acted as a competitive inhibitor for adenosine, cytidine, and uridine 5'-triphosphates and as a noncompetitive inhibitor for guanosine 5'-triphosphate. The bacteriocin did not inhibit RNA polymerase from chicken embryos. PMID:6177280

  2. Metronidazole- and Carbapenem-Resistant Bacteroides thetaiotaomicron Isolated in Rochester, Minnesota, in 2014

    PubMed Central

    Sadarangani, Sapna P.; Cunningham, Scott A.; Jeraldo, Patricio R.; Wilson, John W.; Khare, Reeti

    2015-01-01

    Emerging antimicrobial resistance in members of the Bacteroides fragilis group is a concern in clinical medicine. Although metronidazole and carbapenem resistance have been reported in Bacteroides thetaiotaomicron, a member of the B. fragilis group, they have not, to the best of our knowledge, been reported together in the same B. thetaiotaomicron isolate. Herein, we report isolation of piperacillin-tazobactam-, metronidazole-, clindamycin-, ertapenem-, and meropenem-resistant B. thetaiotaomicron from a patient with postoperative intra-abdominal abscess and empyema. Whole-genome sequencing demonstrated the presence of nimD with at least a portion of IS1169 upstream, a second putative nim gene, two β-lactamase genes (one of which has not been previously reported), two tetX genes, tetQ, ermF, two cat genes, and a number of efflux pumps. This report highlights emerging antimicrobial resistance in B. thetaiotaomicron and the importance of identification and antimicrobial susceptibility testing of selected anaerobic bacteria. PMID:25941219

  3. Bacteroides in the Infant Gut Consume Milk Oligosaccharides via Mucus-Utilization Pathways

    PubMed Central

    Marcobal, A.; Barboza, M.; Sonnenburg, E.D.; Pudlo, N.; Martens, E.C.; Desai, P.; Lebrilla, C.B.; Weimer, B.C.; Mills, D.A.; German, J.B.; Sonnenburg, J.L.

    2011-01-01

    Summary Newborns are colonized with an intestinal microbiota shortly after birth but the factors governing the retention and abundance of specific microbial lineages are unknown. Nursing infants consume human milk oligosaccharides (HMOs) that pass undigested to the distal gut where they may be digested by microbes. We determined that the prominent neonate gut residents, Bacteroides thetaiotaomicron and Bacteroides fragilis, induce the same genes during HMO consumption that are used to harvest host mucus glycans, which are structurally similar to HMOs. Lacto-N-neotetraose, a specific HMO component, selects for HMO-adapted species such as Bifidobacterium infantis, which cannot use mucus, and provides a selective advantage to B. infantis in vivo when bi-associated with B. thetaiotaomicron in the gnotobiotic mouse gut. This indicates that the complex oligosaccharide mixture within HMOs attracts both mutualistic mucus-adapted species and HMO-adapted bifidobacteria to the infant intestine that likely facilitate both milk and future solid food digestion. PMID:22036470

  4. Complete genome sequence of Bacteroides helcogenes type strain (P 36-108T)

    SciTech Connect

    Pati, Amrita; Gronow, Sabine; Zeytun, Ahmet; Lapidus, Alla L.; Nolan, Matt; Hammon, Nancy; Deshpande, Shweta; Cheng, Jan-Fang; Tapia, Roxanne; Han, Cliff; Goodwin, Lynne A.; Pitluck, Sam; Liolios, Konstantinos; Pagani, Ioanna; Ivanova, N; Mavromatis, K; Chen, Amy; Palaniappan, Krishna; Land, Miriam L; Hauser, Loren John; Chang, Yun-Juan; Jeffries, Cynthia; Detter, J. Chris; Brambilla, Evelyne-Marie; Rohde, Manfred; Goker, Markus; Woyke, Tanja; Bristow, James; Eisen, Jonathan; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Lucas, Susan

    2011-01-01

    Bacteroides helcogenes Benno et al. 1983 is of interest because of its isolated phylogenetic location and, although it has been found in pig feces and is known to be pathogenic for pigs, occurrence of this bacterium is rare and it does not cause significant damage in intensive animal husbandry. The genome of B. helcogenes P 36-108T is already the fifth completed and published type strain genome from the genus Bacteroides in the family Bacteroidaceae. The 3,998,906 bp long genome with its 3,353 protein-coding and 83 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  5. Characterization of bactericidal activity of clindamycin against Bacteroides fragilis via kill curve methods.

    PubMed Central

    Klepser, M E; Banevicius, M A; Quintiliani, R; Nightingale, C H

    1996-01-01

    Kill curves were determined for five isolates of Bacteroides fragilis with clindamycin at concentrations equal to the MIC or to 4, 16, and 64 times the MIC. Examination of plots of log CFU per milliliter versus time revealed no association between the clindamycin concentration and the rate and extent of the bactericidal activity against B. fragilis at or below 64 times the MIC. PMID:8843310

  6. Root Hair Deformations Associated with Fractionated Extracts from Rhizobium trifolii†

    PubMed Central

    Ervin, Sean E.; Hubbell, David H.

    1985-01-01

    Components from culture fluid and whole cells of Rhizobium trifolii were examined for effects on root hair morphology of white clover seedlings (Trifolium repens var. Ladino). Cell-free culture fluid, exopolysaccharides, supernatant fluid from the precipitation of the exopolysaccharides, capsular polysaccharides, lipopolysaccharides, and a protein fraction from culture fluids were assayed for morphogenetic effects on the root hairs of axenically grown clover seedlings. Crude fractions were chromatographed on Bio Gel A-5m (Bio-Rad Laboratories), and fractions collected were similarly assayed. Hexose, uronic acid, and protein concentrations were determined for all fractions assayed. Gel chromatography indicated the materials with deforming ability to be of high molecular weight (>10,000). For all fractions except exopolysaccharide, deforming ability was associated with a protein component. This suggested that two components were associated with deformation; both contained polysaccharides and one contained protein. Crude fractions differed in their ability to cause deformations and indicated the following relative ability (in decreasing order) to deform root hairs: cell-free culture fluid, capsular polysaccharides, protein from culture fluids, exopolysaccharide, and cell envelope. Lipopolysaccharides had no effect. Images PMID:16346709

  7. Succinate transport by free-living forms of Rhizobium japonicum.

    PubMed Central

    McAllister, C F; Lepo, J E

    1983-01-01

    We have demonstrated that the transport of succinate into the cells of Rhizobium japonicum strains USDA 110 and USDA 217 is severely inhibited by cyanide, azide, and 2,4-dinitrophenol, but not by arsenate. These results suggest an active mechanism of transport that is dependent on an energized membrane, but does not directly utilize ATP. The apparent Km for succinate was 3.8 microM for strain USDA 110 and 1.8 microM for strain USDA 217; maximal transport velocities were 1.5 and 3.3 nmol of succinate per min per mg of protein, respectively. The expression of the succinate uptake activity was inducible rather than constitutive, with succinate and structurally related compounds being the most effective inducers. The mechanism showed some specificity for succinate and similar organic acids; fumarate and L-malate were classical competitive inhibitors of the system. In general, the best competing compounds were also the best carbon substrates for induction of succinate uptake activity. EDTA inhibited the transport of succinate, implying a role for divalent cations in the system. When various divalent cations were used to reconstitute EDTA-inhibited activity, Ca2+ was most effective, followed by Mg2+, which restored activity at about half the efficiency of Ca2+. Growth media that were supplemented with increased Ca2+ concentration supported more rapid growth with succinate as the carbon substrate, and cells from such media showed higher specific activities of succinate transport. PMID:6402487

  8. High catalase production by Rhizobium radiobacter strain 2-1.

    PubMed

    Nakayama, Mami; Nakajima-Kambe, Toshiaki; Katayama, Hideki; Higuchi, Kazuhiko; Kawasaki, Yoshio; Fuji, Ryujiro

    2008-12-01

    To promote the application of catalase for treating wastewater containing hydrogen peroxide, bacteria exhibiting high catalase activity were screened. A bacterium, designated strain 2-1, with high catalase activity was isolated from the wastewater of a beverage factory that uses hydrogen peroxide. Strain 2-1 was identified as Rhizobium radiobacter (formerly known as Agrobacterium tumefaciens) on the basis of both phenotypic and genotypic characterizations. Although some strains of R. radiobacter are known plant pathogens, polymerase chain reaction (PCR) analysis showed that strain 2-1 has no phytopathogenic factor. Compared with a type strain of R. radiobacter, the specific catalase activity of strain 2-1 was approximately 1000-fold. Moreover, Strain 2-1 grew faster and exhibited considerably higher catalase activity than other microorganisms that have been used for industrial catalase production. Strain 2-1 is harmless to humans and the environment and produces catalase efficiently, suggesting that strain 2-1 is a good resource for the mass production of catalase for the treatment of hydrogen peroxide-containing wastewater. PMID:19134550

  9. Polysaccharide synthesis in relation to nodulation behavior of Rhizobium leguminosarum.

    PubMed Central

    Breedveld, M W; Cremers, H C; Batley, M; Posthumus, M A; Zevenhuizen, L P; Wijffelman, C A; Zehnder, A J

    1993-01-01

    In this study, we characterized four Tn5 mutants derived from Rhizobium leguminosarum RBL5515 with respect to synthesis and secretion of cellulose fibrils, extracellular polysaccharides (EPS), capsular polysaccharides, and cyclic beta-(1,2)-glucans. One mutant, strain RBL5515 exo-344::Tn5, synthesizes residual amounts of EPS, the repeating unit of which lacks the terminal galactose molecule and the substituents attached to it. On basis of the polysaccharide production pattern of strain RBL5515 exo-344::Tn5, the structural features of the polysaccharides synthesized, and the results of an analysis of the enzyme activities involved, we hypothesize that this strain is affected in a galactose transferase involved in the synthesis of EPS only. All four mutants failed to nodulate plants belonging to the pea cross-inoculation group; on Vicia sativa they induced root hair deformation and rare abortive infection threads. All of the mutants appeared to be pleiotropic, since in addition to defects in the synthesis of EPS, lipopolysaccharide, and/or capsular polysaccharides significant increases in the synthesis and secretion of cyclic beta-(1,2)-glucans were observed. We concluded that it is impossible to correlate a defect in the synthesis of a particular polysaccharide with nodulation characteristics. Images PMID:8423148

  10. Physiology of ex planta nitrogenase activity in Rhizobium japonicum

    SciTech Connect

    Agarwal, A.K.; Keister, D.L.

    1983-05-01

    Thirty-nine wild-type strains of Rhizobium japonicum have been studied for their ability to synthesize nitrogenase ex planta in defined liquid media under microaerobic conditions. Twenty-one produced more than trace amounts of acetylene reduction activity, but only a few of these yielded high activity. The oxygen response curves were similar for most of the nitrogenase-positive strains. The strains derepressible for activity had several phenotypic characteristics different from non-derepressible strains. These included slower growth and lower oxygen consumption under microaerobic conditions and lower extracellular polysaccharide production. Extracellular polysaccharide production during growth on gluconate in every nitrogenase-positive strain assayed was lower under both aerobic and microaerobic conditions than the non-depressible strains. These phenotypic characteristics may be representative of a genotype of a subspecies of R. japonicum. These studies were done in part to enlarge the base number of strains available for studies on the physiology, biochemistry, and genetics of nitrogen fixation. (35 Refs.)

  11. Characterization of swarming motility in Rhizobium leguminosarum bv. viciae.

    PubMed

    Tambalo, Dinah D; Yost, Christopher K; Hynes, Michael F

    2010-06-01

    We have characterized swarming motility in Rhizobium leguminosarum strains 3841 and VF39SM. Swarming was dependent on growth on energy-rich media, and both agar concentration and incubation temperature were critical parameters for surface migration. A cell density-dependent lag period was observed before swarming motility was initiated. Surface migration began 3-5 days after inoculation and a full swarming phenotype was observed 3 weeks after inoculation. The swarming front was preceded by a clear extracellular matrix, from which we failed to detect surfactants. The edge of the swarming front formed by VF39SM was characterized by hyperflagellated cells arranged in rafts, whereas the cells at the point of inoculation were indistinguishable from vegetative cells. Swarmer cells formed by 3841, in contrast, showed a minor increase in flagellation, with each swarmer cell exhibiting an average of three flagellar filaments, compared with an average of two flagella per vegetative cell. Reflective of their hyperflagellation, the VF39SM swarmer cells demonstrated an increased expression of flagellar genes. VF39SM swarmed better than 3841 under all the conditions tested, and the additional flagellation in VF39SM swarm cells may contribute to this difference. Metabolism of the supplemented carbon source appeared to be necessary for surface migration as strains incapable of utilizing the carbon source failed to swarm. We also observed that swarmer cells have increased resistance to several antibiotics. PMID:20455952

  12. Synthesis and accumulation of poly(3-hydroxybutyric acid) by Rhizobium sp.

    PubMed

    Manna, A; Pal, S; Paul, A K

    2000-01-01

    Forty-two Rhizobium strains obtained from different culture collections were evaluated quantitatively for poly(3-hydroxy-butyric acid) [PHB] production in shake flask culture. The majority of the strains produced the maximum amount of PHB during the late exponential or stationary phase of growth. Synthesis and accumulation of PHB in different species of Rhizobium were found to vary between 1-38% of their dry biomass. Growth and PHB production by the Rhizobium strain TAL-640 were greatly influenced by the C-source and D-mannitol was fundamental to both processes. The identity and purity of PHB isolated from TAL-640 have also been confirmed by UV-, IR- and 1H-NMR spectroscopic analyses. PMID:10866363

  13. Herbivores alter the fitness benefits of a plant-rhizobium mutualism

    NASA Astrophysics Data System (ADS)

    Heath, Katy D.; Lau, Jennifer A.

    2011-03-01

    Mutualisms are best understood from a community perspective, since third-party species have the potential to shift the costs and benefits in interspecific interactions. We manipulated plant genotypes, the presence of rhizobium mutualists, and the presence of a generalist herbivore and assessed the performance of all players in order to test whether antagonists might alter the fitness benefits of plant-rhizobium mutualism, and vice versa how mutualists might alter the fitness consequences of plant-herbivore antagonism. We found that plants in our experiment formed more associations with rhizobia (root nodules) in the presence of herbivores, thereby increasing the fitness benefits of mutualism for rhizobia. In contrast, the effects of rhizobia on herbivores were weak. Our data support a community-dependent view of these ecological interactions, and suggest that consideration of the aboveground herbivore community can inform ecological and evolutionary studies of legume-rhizobium interactions.

  14. Different metabolic features of Bacteroides fragilis growing in the presence of glucose and exopolysaccharides of bifidobacteria.

    PubMed

    Rios-Covian, David; Sánchez, Borja; Salazar, Nuria; Martínez, Noelia; Redruello, Begoña; Gueimonde, Miguel; de Los Reyes-Gavilán, Clara G

    2015-01-01

    Bacteroides is among the most abundant microorganism inhabiting the human intestine. They are saccharolytic bacteria able to use dietary or host-derived glycans as energy sources. Some Bacteroides fragilis strains contribute to the maturation of the immune system but it is also an opportunistic pathogen. The intestine is the habitat of most Bifidobacterium species, some of whose strains are considered probiotics. Bifidobacteria can synthesize exopolysaccharides (EPSs), which are complex carbohydrates that may be available in the intestinal environment. We studied the metabolism of B. fragilis when an EPS preparation from bifidobacteria was added to the growth medium compared to its behavior with added glucose. 2D-DIGE coupled with the identification by MALDI-TOF/TOF evidenced proteins that were differentially produced when EPS was added. The results were supported by RT-qPCR gene expression analysis. The intracellular and extracellular pattern of certain amino acids, the redox balance and the α-glucosidase activity were differently affected in EPS with respect to glucose. These results allowed us to hypothesize that three general main events, namely the activation of amino acids catabolism, enhancement of the transketolase reaction from the pentose-phosphate cycle, and activation of the succinate-propionate pathway, promote a shift of bacterial metabolism rendering more reducing power and optimizing the energetic yield in the form of ATP when Bacteroides grow with added EPSs. Our results expand the knowledge about the capacity of B. fragilis for adapting to complex carbohydrates and amino acids present in the intestinal environment. PMID:26347720

  15. Different metabolic features of Bacteroides fragilis growing in the presence of glucose and exopolysaccharides of bifidobacteria

    PubMed Central

    Rios-Covian, David; Sánchez, Borja; Salazar, Nuria; Martínez, Noelia; Redruello, Begoña; Gueimonde, Miguel; de los Reyes-Gavilán, Clara G.

    2015-01-01

    Bacteroides is among the most abundant microorganism inhabiting the human intestine. They are saccharolytic bacteria able to use dietary or host-derived glycans as energy sources. Some Bacteroides fragilis strains contribute to the maturation of the immune system but it is also an opportunistic pathogen. The intestine is the habitat of most Bifidobacterium species, some of whose strains are considered probiotics. Bifidobacteria can synthesize exopolysaccharides (EPSs), which are complex carbohydrates that may be available in the intestinal environment. We studied the metabolism of B. fragilis when an EPS preparation from bifidobacteria was added to the growth medium compared to its behavior with added glucose. 2D-DIGE coupled with the identification by MALDI-TOF/TOF evidenced proteins that were differentially produced when EPS was added. The results were supported by RT-qPCR gene expression analysis. The intracellular and extracellular pattern of certain amino acids, the redox balance and the α-glucosidase activity were differently affected in EPS with respect to glucose. These results allowed us to hypothesize that three general main events, namely the activation of amino acids catabolism, enhancement of the transketolase reaction from the pentose-phosphate cycle, and activation of the succinate-propionate pathway, promote a shift of bacterial metabolism rendering more reducing power and optimizing the energetic yield in the form of ATP when Bacteroides grow with added EPSs. Our results expand the knowledge about the capacity of B. fragilis for adapting to complex carbohydrates and amino acids present in the intestinal environment. PMID:26347720

  16. Biochemical and serological characterization of Bacteroides intermedius strains isolated from the deep periodontal pocket.

    PubMed Central

    Dahlén, G; Wikström, M; Renvert, S; Gmür, R; Guggenheim, B

    1990-01-01

    Fifty-one fluorescence-positive black-pigmented Bacteroides strains obtained from 51 patients with deep periodontal pockets (greater than 6 mm) were identified and characterized. Fifty of these strains were presumptively identified as Bacteroides intermedius according to the indole reaction. This was confirmed by further biochemical characterization. The 50 strains from diseased sites were then compared with 16 B. intermedius strains isolated from periodontally healthy individuals with no signs of destructive periodontal disease. Tests for antimicrobial susceptibility showed similar patterns for all 50 pocket-derived strains, except for one beta-lactamase-positive strain that was resistant to penicillin G and ampicillin. Forty-seven strains were tested for binding of three monoclonal antibodies defining three distinct serogroups of B. intermedius. Thirty-one strains belonged to serogroup I, three to serogroup II and thirteen to serogroup III. In comparison to the strains from the shallow periodontal pockets, serogroup I was significantly overrepresented in the patient group with periodontal disease. We conclude that saccharolytic black-pigmented Bacteroides species from deep periodontal pockets constituted, with very rare exceptions, a biochemically homogeneous but antigenically heterogeneous group of B. intermedius and that serogroup I is predominantly found in deep periodontal lesions. PMID:2229351

  17. Genetic Locus Required for Antigenic Maturation of Rhizobium etli CE3 Lipopolysaccharide

    PubMed Central

    Duelli, Dominik M.; Tobin, Andrea; Box, Jodie M.; Kolli, V. S. Kumar; Carlson, Russell W.; Noel, K. Dale

    2001-01-01

    Rhizobium etli modifies lipopolysaccharide (LPS) structure in response to environmental signals, such as low pH and anthocyanins. These LPS modifications result in the loss of reactivity with certain monoclonal antibodies. The same antibodies fail to recognize previously isolated R. etli mutant strain CE367, even in the absence of such environmental cues. Chemical analysis of the LPS in strain CE367 demonstrated that it lacked the terminal sugar of the wild-type O antigen, 2,3,4-tri-O-methylfucose. A 3-kb stretch of DNA, designated as lpe3, restored wild-type antigenicity when transferred into CE367. From the sequence of this DNA, five open reading frames were postulated. Site-directed mutagenesis and complementation analysis suggested that the genes were organized in at least two transcriptional units, both of which were required for the production of LPS reactive with the diagnostic antibodies. Growth in anthocyanins or at low pH did not alter the specific expression of gusA from the transposon insertion of mutant CE367, nor did the presence of multiple copies of lpe3 situated behind a strong, constitutive promoter prevent epitope changes induced by these environmental cues. Mutations of the lpe genes did not prevent normal nodule development on Phaseolus vulgaris and had very little effect on the occupation of nodules in competition with the wild-type strain. PMID:11567006

  18. Assignment of symbiotic developmental phenotypes to common and specific nodulation (nod) genetic loci of Rhizobium meliloti.

    PubMed Central

    Debellé, F; Rosenberg, C; Vasse, J; Maillet, F; Martinez, E; Dénarié, J; Truchet, G

    1986-01-01

    Rhizobium meliloti nodulation (nod) genes required for specific infection and nodulation of alfalfa have been cloned. Transposon Tn5 mutagenesis defined three nod regions spanning 16 kilobases of the pSym megaplasmid. Genetic and cytological studies of 62 nodulation-defective mutants allowed the assignment of symbiotic developmental phenotypes to common and specific nod loci. Root hair curling was determined by both common (region I) and specific (region III) nod transcription units; locus IIIb (nodH gene) positively controlled curling on the homologous host alfalfa, whereas loci IIIa (nodFE) and IIIb (nodH) negatively controlled curling on heterologous hosts. Region I (nodABC) was required for bacterial penetration and infection thread initiation in shepherd's crooks, and the nodFE transcription unit controlled infection thread development within the alfalfa root hair. In contrast, induction of nodule organogenesis, which can be triggered from a distance, seemed to be controlled by common nodABC genes and not to require specific nod genes nodFE and nodH. Region II affected the efficiency of hair curling and infection thread formation. Images PMID:3023297

  19. Role of nickel in membrane-bound hydrogenase and nickel metabolism in Rhizobium japonicum

    SciTech Connect

    Stults, L.W.

    1986-01-01

    The membrane-bound hydrogenase of Rhizobium japonicum requires nickel for activity. Radioactive /sup 63/Ni co-migrates with hydrogenase activity in native gel systems and co-elutes with purified hydrogenase form an affinity matrix column. A simplified scheme for the purification of hydrogenase has been developed and constitutes the first report of the aerobic purification of this enzyme from R. japonicum. The aerobic purification utilizes the general affinity matrix. Reactive Red 120-agarose and results in higher specific activity and yield of enzyme than previously reported. The stability of aerobically purified hydrogenase to oxygen is substantially greater than that reported for anaerobically isolated enzyme. Reduction of the aerobically purified enzyme in the presence of oxygen, however, results in the rapid loss of activity. R. japonicum cells accumulate nickel during heterotrophic growth and as non-growing cells. The hydrogenase constitutive mutant SR470 accumulates substantially greater amounts of nickel under both conditions. Kinetic studies indicate that the nickel uptake system in the hydrogenase constitutive mutant SR470 is upregulated relative to SRwt cells. The uptake system is specific for nickel, although a 10-fold excess (relative to nickel) of copper or zinc inhibits nickel uptake. The nickel uptake system appears to require energy. Under nickel-free conditions hydrogenase protein is not synthesized as determined by cross-reactivity with antibodies directed against hydrogenase, indicating that nickel regulates the formation of the enzyme as well as being a constituent of the active protein.

  20. The rkpGHI and -J genes are involved in capsular polysaccharide production by Rhizobium meliloti.

    PubMed Central

    Kiss, E; Reuhs, B L; Kim, J S; Kereszt, A; Petrovics, G; Putnoky, P; Dusha, I; Carlson, R W; Kondorosi, A

    1997-01-01

    The first complementation unit of the fix-23 region of Rhizobium meliloti, which comprises six genes (rkpAB-CDEF) exhibiting similarity to fatty acid synthase genes, is required for the production of a novel type of capsular polysaccharide that is involved in root nodule development and structurally analogous to group II K antigens found in Escherichia coli (G. Petrovics, P. Putnoky, R. Reuhs, J. Kim, T. A. Thorp, K. D. Noel, R. W. Carlson, and A. Kondorosi, Mol. Microbiol. 8:1083-1094, 1993; B. L. Reuhs, R. W. Carlson, and J. S. Kim, J. Bacteriol. 175:3570-3580, 1993). Here we present the nucleotide sequence for the other three complementation units of the fix-23 locus, revealing the presence of four additional open reading frames assigned to genes rkpGHI and -J. The putative RkpG protein shares similarity with acyltransferases, RkpH is homologous to short-chain alcohol dehydrogenases, and RkpJ shows significant sequence identity with bacterial polysaccharide transport proteins, such as KpsS of E. coli. No significant homology was found for RkpI. Biochemical and immunological analysis of Tn5 derivatives for each gene demonstrated partial or complete loss of capsular polysaccharides from the cell surface; on this basis, we suggest that all genes in the fix-23 region are required for K-antigen synthesis or transport. PMID:9079896

  1. Characterization of Rhizobium grahamii extrachromosomal replicons and their transfer among rhizobia

    PubMed Central

    2014-01-01

    Background Rhizobium grahamii belongs to a new phylogenetic group of rhizobia together with Rhizobium mesoamericanum and other species. R. grahamii has a broad-host-range that includes Leucaena leucocephala and Phaseolus vulgaris, although it is a poor competitor for P. vulgaris nodulation in the presence of Rhizobium etli or Rhizobium phaseoli strains. This work analyzed the genome sequence and transfer properties of R. grahamii plasmids. Results Genome sequence was obtained from R. grahamii CCGE502 type strain isolated from Dalea leporina in Mexico. The CCGE502 genome comprises one chromosome and two extrachromosomal replicons (ERs), pRgrCCGE502a and pRgrCCGE502b. Additionally, a plasmid integrated in the CCGE502 chromosome was found. The genomic comparison of ERs from this group showed that gene content is more variable than average nucleotide identity (ANI). Well conserved nod and nif genes were found in R. grahamii and R. mesoamericanum with some differences. R. phaseoli Ch24-10 genes expressed in bacterial cells in roots were found to be conserved in pRgrCCGE502b. Regarding conjugative transfer we were unable to transfer the R. grahamii CCGE502 symbiotic plasmid and its megaplasmid to other rhizobial hosts but we could transfer the symbiotic plasmid to Agrobacterium tumefaciens with transfer dependent on homoserine lactones. Conclusion Variable degrees of nucleotide identity and gene content conservation were found among the different R. grahamii CCGE502 replicons in comparison to R. mesoamericanum genomes. The extrachromosomal replicons from R. grahamii were more similar to those found in phylogenetically related Rhizobium species. However, limited similarities of R. grahamii CCGE502 symbiotic plasmid and megaplasmid were observed in other more distant Rhizobium species. The set of conserved genes in R. grahamii comprises some of those that are highly expressed in R. phaseoli on plant roots, suggesting that they play an important role in root colonization

  2. Rhizobium acidisoli sp. nov., isolated from root nodules of Phaseolus vulgaris in acid soils.

    PubMed

    Román-Ponce, Brenda; Jing Zhang, Yu; Soledad Vásquez-Murrieta, María; Hua Sui, Xin; Feng Chen, Wen; Carlos Alberto Padilla, Juan; Wu Guo, Xian; Lian Gao, Jun; Yan, Jun; Hong Wei, Ge; Tao Wang, En

    2016-01-01

    Two Gram-negative, aerobic, non-motile, rod-shaped bacterial strains, FH13T and FH23, representing a novel group of Rhizobium isolated from root nodules of Phaseolus vulgaris in Mexico, were studied by a polyphasic analysis. Phylogeny of 16S rRNA gene sequences revealed them to be members of the genus Rhizobium related most closely to 'Rhizobium anhuiense' CCBAU 23252 (99.7 % similarity), Rhizobium leguminosarum USDA 2370T (98.6 %), and Rhizobium sophorae CCBAU 03386T and others ( ≤ 98.3 %). In sequence analyses of the housekeeping genes recA, glnII and atpD, both strains formed a subclade distinct from all defined species of the genus Rhizobium at sequence similarities of 82.3-94.0 %, demonstrating that they represented a novel genomic species in the genus Rhizobium. Mean levels of DNA-DNA relatedness between the reference strain FH13T and the type strains of related species varied between 13.0 ± 2.0 and 52.1 ± 1.2 %. The DNA G+C content of strain FH13T was 63.5 mol% (Tm). The major cellular fatty acids were 16 : 0, 17 : 0 anteiso, 18 : 0, summed feature 2 (12 : 0 aldehyde/unknown 10.928) and summed feature 8 (18 : 1ω7c). The fatty acid 17 : 1ω5c was unique for this strain. Some phenotypic features, such as failure to utilize adonitol, l-arabinose, d-fructose and d-fucose, and ability to utilize d-galacturonic acid and itaconic acid as carbon source, could also be used to distinguish strain FH13T from the type strains of related species. Based upon these results, a novel species, Rhizobium acidisoli sp. nov., is proposed, with FH13T ( = CCBAU 101094T = HAMBI 3626T = LMG 28672T) as the type strain. PMID:26530784

  3. Specific Detection of Bradyrhizobium and Rhizobium Strains Colonizing Rice (Oryza sativa) Roots by 16S-23S Ribosomal DNA Intergenic Spacer-Targeted PCR

    PubMed Central

    Tan, Zhiyuan; Hurek, Thomas; Vinuesa, Pablo; Müller, Peter; Ladha, Jagdish K.; Reinhold-Hurek, Barbara

    2001-01-01

    In addition to forming symbiotic nodules on legumes, rhizobial strains are members of soil or rhizosphere communities or occur as endophytes, e.g., in rice. Two rhizobial strains which have been isolated from root nodules of the aquatic legumes Aeschynomene fluminensis (IRBG271) and Sesbania aculeata (IRBG74) were previously found to promote rice growth. In addition to analyzing their phylogenetic positions, we assessed the suitability of the 16S-23S ribosomal DNA (rDNA) intergenic spacer (IGS) sequences for the differentiation of closely related rhizobial taxa and for the development of PCR protocols allowing the specific detection of strains in the environment. 16S rDNA sequence analysis (sequence identity, 99%) and phylogenetic analysis of IGS sequences showed that strain IRBG271 was related to but distinct from Bradyrhizobium elkanii. Rhizobium sp. (Sesbania) strain IRBG74 was located in the Rhizobium-Agrobacterium cluster as a novel lineage according to phylogenetic 16S rDNA analysis (96.8 to 98.9% sequence identity with Agrobacterium tumefaciens; emended name, Rhizobium radiobacter). Strain IRBG74 harbored four copies of rRNA operons whose IGS sequences varied only slightly (2 to 9 nucleotides). The IGS sequence analyses allowed intraspecies differentiation, especially in the genus Bradyrhizobium, as illustrated here for strains of Bradyrhizobium japonicum, B. elkanii, Bradyrhizobium liaoningense, and Bradyrhizobium sp. (Chamaecytisus) strain BTA-1. It also clearly differentiated fast-growing rhizobial species and strains, albeit with lower statistical significance. Moreover, the high sequence variability allowed the development of highly specific IGS-targeted nested-PCR assays. Strains IRBG74 and IRBG271 were specifically detected in complex DNA mixtures of numerous related bacteria and in the DNA of roots of gnotobiotically cultured or even of soil-grown rice plants after inoculation. Thus, IGS sequence analysis is an attractive technique for both microbial

  4. Efficient and regioselective synthesis of globotriose by a novel α-galactosidase from Bacteroides fragilis.

    PubMed

    Gong, Wei; Xu, Li; Gu, Guofeng; Lu, Lili; Xiao, Min

    2016-08-01

    Globotriose (Galα1-4Galβ1-4Glc) is an important cell surface epitope that acts as the receptor for Shiga-like toxins, and it is also the core structure of Globo H and SSEA4 that are tumor-associated glycans. Hence, the enzymatic synthesis of globotriose would be necessary for the development of carbohydrate-based therapeutics for bacterial infections and cancers. Here, a novel GH27 α-galactosidase gene (agaBf3S), a 1521-bp DNA encoding 506 amino acids with a calculated molecular mass of 57.7 kDa, from Bacteroides fragilis NCTC9343 was cloned and heterogeneously expressed in Escherichia coli. The recombinant enzyme AgaBf3S preferentially hydrolyzed p-nitrophenyl-α-D-galactopyranoside (pNPαGal) in all tested nitrophenyl glycosides. It showed maximum activity at pH 4.5 and 40 °C, and it was stable at pH 4.0-11.0 below 40 °C and metal-independent. The K m and k cat values for pNPαGal, melibiose, and globotriose were 1.27 mM and 172.97 S(-1), 62.76 mM and 17.74 S(-1), and 4.62 mM and 388.45 S(-1), respectively. AgaBf3S could transfer galactosyl residue from pNPαGal to lactose (Galβ1-4Glc) with high efficiency and strict α1-4 regioselectivity. The effects of initial substrate concentration, pH, temperature, and reaction time on transglycosylation reaction catalyzed by AgaBf3S were studied in detail. AgaBf3S could synthesize globotriose as a single transglycosylation product with a maximum yield of 32.4 % from 20 mM pNPαGal and 500 mM lactose (pH 4.5) at 40 °C for 30 min. This new one-enzyme one-step synthetic reaction is simple, fast, and low cost, which provides a promising alternative to the current synthetic methods for access to pharmaceutically important Galα1-4-linked oligosaccharides. PMID:27020280

  5. Autecology in Rhizospheres and Nodulating Behavior of Indigenous Rhizobium trifolii†

    PubMed Central

    Demezas, David H.; Bottomley, Peter J.

    1986-01-01

    Indigenous serotype 1-01 of Rhizobium trifolii occupied significantly fewer nodules (6%) on plants of soil-grown noninoculated subterranean clover (Trifolium subterraneum L.) cv. Woogenellup than on cv. Mt. Barker (36%) sampled at the flowering stage of growth. Occupancy by indigenous serotype 2-01, was not significantly different on the two cultivars (16 and 26%). Serotype-specific, fluorescent-antibody conjugates were synthesized and used to enumerate the indigenous serotypes in host (clovers) and nonhost (annual rye-grass, Lolium multiflorum L.) rhizospheres and in nonplanted soil. The form and concentration of Ca2+ in the flocculating mixture and the presence of phosphate anions in the extracting solution were both critical for enumerating R. trifolii in Whobrey soil. The two serotypes were present in similar numbers in nonplanted soil (ca. 106 per g of soil) and each represented ca. 10% of the total R. trifolii population. Although host rhizospheres did not preferentially stimulate either serotype, the mean population densities of serotype 2-01 were significantly greater (P = 0.05) than those of serotype 1-01 in clover rhizospheres on 8 of 14 samplings made between the time of seeding and the appearance of nodules (day 12). In this experiment, and in contrast to our earlier findings, serotype 1-01 occupied significantly fewer (P ≤ 0.05) of the nodules (7 to 16%) on both cultivars than serotype 2-01 (51%) when sampled at 4 weeks. Differences between cultivars became apparent as the plants matured. There was a threefold increase (7 to 21%) in nodules occupied by serotype 1-01 on cv. Mt. Barker between 4 and 16 weeks. This was accompanied by increases in nodules coinhabited by both nonidentifiable occupants and either serotype 1-01 (0 to 20%) or 2-01 (11 to 51%). No increases in either of these parameters were observed on cv. Woogenellup. PMID:16347198

  6. Enhanced Symbiotic Performance by Rhizobium tropici Glycogen Synthase Mutants

    PubMed Central

    Marroquí, Silvia; Zorreguieta, Angeles; Santamaría, Carmen; Temprano, Francisco; Soberón, Mario; Megías, Manuel; Downie, J. Allan

    2001-01-01

    We isolated a Tn5-induced Rhizobium tropici mutant that has enhanced capacity to oxidize N,N-dimethyl-p-phenylendiamine (DMPD) and therefore has enhanced respiration via cytochrome oxidase. The mutant had increased levels of the cytochromes c1 and CycM and a small increase in the amount of cytochrome aa3. In plant tests, the mutant increased the dry weight of Phaseolus vulgaris plants by 20 to 38% compared with the control strain, thus showing significantly enhanced symbiotic performance. The predicted product of the mutated gene is homologous to glycogen synthases from several bacteria, and the mutant lacked glycogen. The DNA sequence of the adjacent gene region revealed six genes predicted to encode products homologous to the following gene products from Escherichia coli: glycogen phosphorylase (glgP), glycogen branching enzyme (glgB), ADP glucose pyrophosphorylase (glgC), glycogen synthase (glgA), phosphoglucomutase (pgm), and glycogen debranching enzyme (glgX). All six genes are transcribed in the same direction, and analysis with lacZ gene fusions suggests that the first five genes are organized in one operon, although pgm appears to have an additional promoter; glgX is transcribed independently. Surprisingly, the glgA mutant had decreased levels of high-molecular-weight exopolysaccharide after growth on glucose, but levels were normal after growth on galactose. A deletion mutant was constructed in order to generate a nonpolar mutation in glgA. This mutant had a phenotype similar to that of the Tn5 mutant, indicating that the enhanced respiration and symbiotic nitrogen fixation and decreased exopolysaccharide were due to mutation of glgA and not to a polar effect on a downstream gene. PMID:11208782

  7. Three Cases of Post-Cataract Surgery Endophthalmitis Due to Rhizobium (Agrobacterium) radiobacter

    PubMed Central

    Moreau-Gaudry, Viviane; Chiquet, Christophe; Boisset, Sandrine; Croize, Jacques; Benito, Yvonne; Cornut, Pierre Loïc; Bron, Alain; Vandenesch, François

    2012-01-01

    We present three unrelated post-cataract surgery endophthalmitis cases caused by Rhizobium radiobacter, hospitalized in three different hospitals. Early diagnosis was obtained in two cases by bacterial DNA detection in vitreous samples. All patients recovered from infection, but pars plana vitrectomy was needed in two patients due to rapid clinical deterioration. PMID:22259203

  8. Three cases of post-cataract surgery endophthalmitis due to Rhizobium (Agrobacterium) radiobacter.

    PubMed

    Moreau-Gaudry, Viviane; Chiquet, Christophe; Boisset, Sandrine; Croize, Jacques; Benito, Yvonne; Cornut, Pierre Loïc; Bron, Alain; Vandenesch, François; Maurin, Max

    2012-04-01

    We present three unrelated post-cataract surgery endophthalmitis cases caused by Rhizobium radiobacter, hospitalized in three different hospitals. Early diagnosis was obtained in two cases by bacterial DNA detection in vitreous samples. All patients recovered from infection, but pars plana vitrectomy was needed in two patients due to rapid clinical deterioration. PMID:22259203

  9. [Construction of the gene library of symbiotic nitrogen-fixing Rhizobium lupini].

    PubMed

    Ivanushkin, A G; Marchenko, G N; Chistoserdov, A Iu; Pushkin, A V; Kretovich, V L

    1990-01-01

    The gene bank of the symbiotic nitrogen-fixing bacterium Rhizobium lupini (effective strain 359a) was constructed on plasmid pAYC31 that was used to transform Escherichia coli C6000. The bank contains 6600 clones. Restriction analysis showed that the size of the mean insertion fragment in the plasmid in 6.5 kb. PMID:2190206

  10. Accumulation of Amino Acids in Rhizobium sp. Strain WR1001 in Response to Sodium Chloride Salinity

    PubMed Central

    Hua, Sui-Sheng T.; Tsai, Victor Y.; Lichens, Georgia M.; Noma, Amy T.

    1982-01-01

    Rhizobium sp. strain WR1001, isolated from the Sonoran Desert by Eskew and Ting, was found to be able to grow in defined medium containing NaCl up to 500 mM, a concentration approaching that of sea water. Therefore, it is a valuable strain for studying the biochemical basis of salt tolerance. Intracellular free glutamate was found to increase rapidly in response to osmotic stress by NaCl. It accounted for 88% of the amino acid pool when the bacterium was grown in 500 mM NaCl. The role of glutamate dehydrogenase in glutamate biosynthesis was examined in several Rhizobium strains. Both NADH- and NADPH-dependent glutamate dehydrogenase activities in various Rhizobium strains were observed. The range of activity differed considerably depending on the particular strain. KCl (500 mM) did not stimulate glutamate dehydrogenase activity, as reported in a number of bacterial strains by Measures. The low activity of glutamate dehydrogenase in Rhizobium sp. strain WR1001 apparently cannot fulfill a biosynthetic function of glutamate formation in response to medium NaCl concentrations. PMID:16346049

  11. Beta-2-linked glucans secreted by fast-growing species of Rhizobium.

    PubMed Central

    York, W S; McNeil, M; Darvill, A G; Albersheim, P

    1980-01-01

    Fast-growing species of Rhizobium were found to secrete low-molecular-weight beta-2-linked glucans when cultured in synthetic liquid medium. These glucans are quite similar to beta-2-linked glucans produced by species of Agrobacterium. No reducing terminus was detected in these glucans. PMID:7372570

  12. Rhizobium anhuiense sp. nov., isolated from effective nodules of Vicia faba and Pisum sativum.

    PubMed

    Zhang, Yu Jing; Zheng, Wen Tao; Everall, Isobel; Young, J Peter W; Zhang, Xiao Xia; Tian, Chang Fu; Sui, Xin Hua; Wang, En Tao; Chen, Wen Xin

    2015-09-01

    Four rhizobia-like strains, isolated from root nodules of Pisum sativum and Vicia faba grown in Anhui and Jiangxi Provinces of China, were grouped into the genus Rhizobium but were distinct from all recognized species of the genus Rhizobium by phylogenetic analysis of 16S rRNA and housekeeping genes. The combined sequences of the housekeeping genes atpD, recA and glnII for strain CCBAU 23252(T) showed 86.9 to 95% similarity to those of known species of the genus Rhizobium. All four strains had nodC and nifH genes and could form effective nodules with Pisum sativum and Vicia faba, and ineffective nodules with Phaseolus vulgaris, but did not nodulate Glycine max, Arachis hypogaea, Medicago sativa, Trifolium repens or Lablab purpureus in cross-nodulation tests. Fatty acid composition, DNA-DNA relatedness and a series of phenotypic tests also separated these strains from members of closely related species. Based on all the evidence, we propose a novel species, Rhizobium anhuiense sp. nov., and designate CCBAU 23252(T) ( = CGMCC 1.12621(T) = LMG 27729(T)) as the type strain. This strain was isolated from a root nodule of Vicia faba and has a DNA G+C content of 61.1 mol% (Tm). PMID:26025940

  13. Genome of Rhizobium sp. UR51a, Isolated from Rice Cropped in Southern Brazilian Fields.

    PubMed

    de Souza, Rocheli; Sant'Anna, Fernando Hayashi; Ambrosini, Adriana; Tadra-Sfeir, Michele; Faoro, Helisson; Pedrosa, Fabio Oliveira; Souza, Emanuel Maltempi; Passaglia, Luciane M P

    2015-01-01

    Rhizobium sp. UR51a is a Gram-negative bacterium isolated from roots of rice plants, and it presents plant growth-promoting abilities. The nutrient uptake in rice plants inoculated with UR51a was satisfactory. The genome of strain UR51a is composed of 5,233,443-bp and harbors 5,079 coding sequences. PMID:25838497

  14. Genome of Rhizobium sp. UR51a, Isolated from Rice Cropped in Southern Brazilian Fields

    PubMed Central

    de Souza, Rocheli; Sant’Anna, Fernando Hayashi; Ambrosini, Adriana; Tadra-Sfeir, Michele; Faoro, Helisson; Pedrosa, Fabio Oliveira; Souza, Emanuel Maltempi

    2015-01-01

    Rhizobium sp. UR51a is a Gram-negative bacterium isolated from roots of rice plants, and it presents plant growth-promoting abilities. The nutrient uptake in rice plants inoculated with UR51a was satisfactory. The genome of strain UR51a is composed of 5,233,443-bp and harbors 5,079 coding sequences. PMID:25838497

  15. Rhizobium selenireducens sp. nov. Validation and inclusion onto the list of organisms with standing in nomenclature.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This is a submission to the list of microorganisms with standing in nomenclature. The list of valid microbial names is maintained by the International Journal of Systematic and Evolutionary Microbiology and we are proposing that Rhizobium selenireducens sp. nov. be added to the list as a valid spec...

  16. Response of Andean and Mesoamerican common bean genotypes to inoculation with rhizobium strains.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In most common bean (Phaseolus vulgaris L.) production regions of Latin America, inoculants are rarely used by farmers in spite of several studies that demonstrate the importance of Rhizobium inoculation on commercial production of legume crops. This study investigated specific bean host plant-Rhizo...

  17. Preservation of Rhizobium viability and symbiotic infectivity by suspension in water

    SciTech Connect

    Crist, D.K.; Wyza, R.E.; Mills, K.K.; Bauer, W.D.; Evans, W.R.

    1984-05-01

    Three Rhizobium japonicum strains and two slow-growing cowpea-type Rhizobium strains were found to remain viable and able to rapidly nodulate their respective hosts after being stored in purified water at ambient temperatures for periods of 1 year and longer. Three fast-growing Rhizobium species did not remain viable under the same water storage conditions. After dilution of slow-growing Rhizobium strains with water to 10/sup 3/ to 10/sup 5/ cells ml/sup -1/, the bacteria multiplied until the viable cell count reached levels of between 10/sub 6/ and 10/sup 7/ cells ml/sup -1/. The viable cell count subsequently remained fairly constant. When the rhizobia were diluted to 10/sup 7/ cells ml/sup -1/, they did not multiply, but full viability was maintained. If the rhizobia were washed and suspended at 10/sup 9/ cells ml/sup -1/, viability slowly declined to 10/sup 7/ cells ml/sup -1/ during 9 months of storage. Scanning electron microscopy showed that no major morphological changes took place during storage. Preservation of slow-growing rhizobia in water suspensions could provide a simple and inexpensive alternative to current methods for the preservation of rhizobia for legume inoculation. 25 references, 7 figures, 2 tables.

  18. Beta-2-linked glucans secreted by fast-growing species of Rhizobium

    SciTech Connect

    York, W.S.; McNeil, M.; Darvill, A.G.; Albersheim, P.

    1980-04-01

    Fast-growing species of Rhizobium were found to secrete low-molecular-weight ..beta..-2-linked glucans when cultured in synthetic liquid medium. These glucans are quite similar to ..beta..-2-linked glucans produced by species of Agrobacterium. No reducing terminus was detected in these glucans.

  19. The structure of legume–rhizobium interaction networks and their response to tree invasions

    PubMed Central

    Le Roux, Johannes J.; Mavengere, Natasha R.; Ellis, Allan G.

    2016-01-01

    Establishing mutualistic interactions in novel environments is important for the successful establishment of some non-native plant species. These associations may, in turn, impact native species interaction networks as non-natives become dominant in their new environments. Using phylogenetic and ecological interaction network approaches we provide the first report of the structure of belowground legume–rhizobium interaction networks and how they change along a gradient of invasion (uninvaded, semi invaded and heavily invaded sites) by Australian Acacia species in South Africa’s Cape Floristic Region. We found that native and invasive legumes interact with distinct rhizobial lineages, most likely due to phylogenetic uniqueness of native and invasive host plants. Moreover, legume–rhizobium interaction networks are not nested, but significantly modular with high levels of specialization possibly as a result of legume–rhizobium co-evolution. Although network topology remained constant across the invasion gradient, composition of bacterial communities associated with native legumes changed dramatically as acacias increasingly dominated the landscape. In stark contrast to aboveground interaction networks (e.g. pollination and seed dispersal) we show that invasive legumes do not infiltrate existing native legume–rhizobium networks but rather form novel modules. This absence of mutualist overlap between native and invasive legumes suggests the importance of co-invading rhizobium–acacia species complexes for Acacia invasion success, and argues against a ubiquitous role for the formation and evolutionary refinement of novel interactions. PMID:27255514

  20. Nodulation of Sesbania Species by Rhizobium (Agrobacterium) Strain IRBG74 and Other Rhizobia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concatenated sequence analysis with 16S rRNA, rpoB and fusA genes identified a strain (IRBG74) isolated from root nodules of the aquatic legume Sesbania cannabina as a close relative of the plant pathogen Rhizobium radiobacter (syn. Agrobacterium tumefaciens). However, DNA:DNA hybridisation with R. ...

  1. Interactions between Bifidobacterium and Bacteroides species in cofermentations are affected by carbon sources, including exopolysaccharides produced by bifidobacteria.

    PubMed

    Rios-Covian, David; Arboleya, Silvia; Hernandez-Barranco, Ana M; Alvarez-Buylla, Jorge R; Ruas-Madiedo, Patricia; Gueimonde, Miguel; de los Reyes-Gavilan, Clara G

    2013-12-01

    Cocultures of strains from two Bifidobacterium and two Bacteroides species were performed with exopolysaccharides (EPS) previously purified from bifidobacteria, with inulin, or with glucose as the carbon source. Bifidobacterium longum NB667 and Bifidobacterium breve IPLA20004 grew in glucose but showed poor or no growth in complex carbohydrates (inulin, EPS E44, and EPS R1), whereas Bacteroides grew well in the four carbon sources tested. In the presence of glucose, the growth of Bacteroides thetaiotaomicron DSM-2079 was inhibited by B. breve, whereas it remained unaffected in the presence of B. longum. Ba. fragilis DSM-2151 contributed to a greater survival of B. longum, promoting changes in the synthesis of short-chain fatty acids (SCFA) and organic acids in coculture with respect to monocultures. In complex carbohydrates, cocultures of bifidobacterium strains with Ba. thetaiotaomicron did not modify the behavior of Bacteroides nor improve the poor growth of bifidobacteria. The metabolic activity of Ba. fragilis in coculture with bifidobacteria was not affected by EPS, but greater survival of bifidobacteria at late stages of incubation occurred in cocultures than in monocultures, leading to a higher production of acetic acid than in monocultures. Therefore, cocultures of Bifidobacterium and Bacteroides can behave differently against fermentable carbohydrates as a function of the specific characteristics of the strains from each species. These results stress the importance of considering specific species and strain interactions and not simply higher taxonomic divisions in the relationship among intestinal microbial populations and their different responses to probiotics and prebiotics. PMID:24077708

  2. Interactions between Bifidobacterium and Bacteroides Species in Cofermentations Are Affected by Carbon Sources, Including Exopolysaccharides Produced by Bifidobacteria

    PubMed Central

    Rios-Covian, David; Arboleya, Silvia; Hernandez-Barranco, Ana M.; Alvarez-Buylla, Jorge R.; Ruas-Madiedo, Patricia; Gueimonde, Miguel

    2013-01-01

    Cocultures of strains from two Bifidobacterium and two Bacteroides species were performed with exopolysaccharides (EPS) previously purified from bifidobacteria, with inulin, or with glucose as the carbon source. Bifidobacterium longum NB667 and Bifidobacterium breve IPLA20004 grew in glucose but showed poor or no growth in complex carbohydrates (inulin, EPS E44, and EPS R1), whereas Bacteroides grew well in the four carbon sources tested. In the presence of glucose, the growth of Bacteroides thetaiotaomicron DSM-2079 was inhibited by B. breve, whereas it remained unaffected in the presence of B. longum. Ba. fragilis DSM-2151 contributed to a greater survival of B. longum, promoting changes in the synthesis of short-chain fatty acids (SCFA) and organic acids in coculture with respect to monocultures. In complex carbohydrates, cocultures of bifidobacterium strains with Ba. thetaiotaomicron did not modify the behavior of Bacteroides nor improve the poor growth of bifidobacteria. The metabolic activity of Ba. fragilis in coculture with bifidobacteria was not affected by EPS, but greater survival of bifidobacteria at late stages of incubation occurred in cocultures than in monocultures, leading to a higher production of acetic acid than in monocultures. Therefore, cocultures of Bifidobacterium and Bacteroides can behave differently against fermentable carbohydrates as a function of the specific characteristics of the strains from each species. These results stress the importance of considering specific species and strain interactions and not simply higher taxonomic divisions in the relationship among intestinal microbial populations and their different responses to probiotics and prebiotics. PMID:24077708

  3. Rhizobium marinum sp. nov., a malachite-green-tolerant bacterium isolated from seawater.

    PubMed

    Liu, Yang; Wang, Run-Ping; Ren, Chong; Lai, Qi-Liang; Zeng, Run-Ying

    2015-12-01

    A motile, Gram-stain-negative, non-pigmented bacterial strain, designated MGL06T, was isolated from seawater of the South China Sea on selection medium containing 0.1 % (w/v) malachite green. Strain MGL06T showed highest 16S rRNA gene sequence similarity to Rhizobium vignae CCBAU 05176T (97.2 %), and shared 93.2-96.9 % with the type strains of other recognized Rhizobium species. Phylogenetic analyses based on 16S rRNA and housekeeping gene sequences showed that strain MGL06T belonged to the genus Rhizobium. Mean levels of DNA-DNA relatedness between strain MGL06T and R. vignae CCBAU 05176T, Rhizobium huautlense S02T and Rhizobium alkalisoli CCBAU 01393T were 20 ± 3, 18 ± 2 and 14 ± 3 %, respectively, indicating that strain MGL06T was distinct from them genetically. Strain MGL06T did not form nodules on three different legumes, and the nodD and nifH genes were also not detected by PCR or based on the draft genome sequence. Strain MGL06T contained Q-10 as the predominant ubiquinone. The major fatty acid was C18 : 1ω7c/C18 : 1ω6c with minor amounts of C19 : 0 cyclo ω8c, C16 : 0 and C18 : 1ω7c 11-methyl. Polar lipids of strain MGL06T included unknown glycolipids, phosphatidylcholine, aminolipid, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, an unknown polar lipid and aminophospholipid. Based on its phenotypic and genotypic data, strain MGL06T represents a novel species of the genus Rhizobium, for which the name Rhizobium marinum sp. nov. is proposed. The type strain is MGL06T ( = MCCC 1A00836T = JCM 30155T). PMID:26374202

  4. Nodulation gene factors and plant response in the Rhizobium-legume symbiosis. [Nodulation

    SciTech Connect

    Long, S.R.

    1990-01-01

    Our original application aimed to identify genes outside the common nod region involved in nodulation and host range of alfalfa. This has been revised by adding other studies on nodulation gene action and removing molecular studies of gene action. Our restated goals and progress are as follows. An early goal was identification and characterization of additional nodulation genes. By means of transposon mutagenesis, mapping and marker exchange we have established 87 independent mutations in a 20kb area represented by plasmid pRmJT5. We discovered four new genes: nodP, nodD3, syrA and syrM. The sequence, start site and protein product for nodFe, nodG, and nodH were also identified. Regulation of nod FEGH was studied. nod FEGH can be induced by luteolin in the presence of noodle; nodD1; noD3 and syrM, a symbiotic regulator gene also increase transcription of nod FEGH. syrA will interact with syrM; syrM also regulates exopolysaccharide genes and is believed to be a master regulator. As part of these studies, an in vitro transcription/translation system for Rhizobium was developed. Adjacent to nodP we discussed nodQ, nodPQ occurrs in two highly consumed copies. nodQ appears by sequence analysis to be similar to initiation and elongation factors, with the highest homology in the GDP binding domain. We have also investigated the nod strain, WL131. WL131 has an insertion, ISRm3, interrupting nodG, and a nonsase mutation in nodH, nodH is responsible for the lack of nodulation. We are currently investigating supernatant factors, host range effects C by spot inoculation, glucaronidase fusion proteins, and are developing, a single root hair inoculation protocol. 7 refs., 6 figs., 1 tab.

  5. Fermentation of fenugreek fiber, psyllium husk, and wheat bran by Bacteroides ovatus V975.

    PubMed

    Al-Khaldi, S F; Martin, S A; Prakash, L

    1999-10-01

    The objective of this study was to evaluate the ability of the human colonic bacterium Bacteroides ovatus V975 to ferment fenugreek fiber (Fenufibers), psyllium husk (Metamucil), and wheat bran (Wheat Chex). Strain V975 was incubated in basal medium that contained 0.1 g of each fiber source for 0, 24, or 48 h. Little digestion of either fiber source was detected over 48 h, and little acetate or succinate was produced. From the lack of significant fiber digestion and fermentation by B. ovatus, it seems that all three fiber sources could be used as dietary supplements to increase roughage in the human diet. PMID:10486060

  6. Efflux Pump Overexpression in Multiple-Antibiotic-Resistant Mutants of Bacteroides fragilis

    PubMed Central

    Pumbwe, Lilian; Glass, Daniel; Wexler, Hannah M.

    2006-01-01

    Multidrug-resistant mutants of a wild-type Bacteroides fragilis strain (strain ADB77) and a quadruple resistance nodulation division family efflux pump deletion mutant (ADB77 ΔbmeB1 ΔbmeB3 ΔbmeB12 ΔbmeB15) were selected with antimicrobials. Ampicillin, doripenem, imipenem, levofloxacin, and metronidazole selected for mutants from both strains; cefoxitin selected for mutants from strain ADB77 only; and sodium dodecyl sulfate selected mutants from ADB77ΔbmeB1 ΔbmeB3 ΔbmeB12 ΔbmeB15 only. The mutants overexpressed one or more efflux pumps. PMID:16940115

  7. Role of Enterotoxigenic Bacteroides fragilis in Children Less Than 5 Years of Age With Diarrhea in Tabriz, Iran

    PubMed Central

    Akhi, Mohammad Taghi; Jedari Seifi, Sirus; Asgharzadeh, Mohammad; Ahangarzadeh Rezaee, Mohammad; Abdoli Oskuei, Shahram; Pirzadeh, Tahereh; Memar, Mohammad Yousef; Alizadeh, Naser; Seifi Yarijan Sofla, Hasan

    2016-01-01

    Background Diarrhea is the most frequent health problem among children in developing countries. Defining the etiology of acute diarrhea is critical to disease therapy and prevention. Some anaerobic bacteria such as Enterotoxigenic Bacteroides fragilis (ETBF) strains cause diarrheal disease by production of enterotoxin in children less than 5 years old. Objectives This study aimed to evaluate the prevalence of ETBF among common bacteria and viruses causing diarrhea in children aged less than five years. Materials and Methods One hundred diarrheal stools were cultured for detection of aerobic and anaerobic pathogen bacteria by direct plating on selective media and antibiotic susceptibility tests were performed according to clinical and laboratory standards institute (CLSI) guidelines on isolates of ETBF. The enterotoxigenic gene among B. fragilis isolates was also investigated using the polymerase chain reaction (PCR) method. Detection of viral pathogens was carried out using the latex agglutination test. Results Ten B. fragilis were isolated from 100 diarrheal fecal specimens. All isolates were susceptible to metronidazole, while 10% were susceptible to clindamycin. Four (40%) ETBF were isolated. Rotaviruses (57.2%) and adenoviruses (18.6%) were the most frequently detected etiological agents. Conclusions ETBF is one of the etiological agents that may cause diarrhea in children but it is not the commonest of them. Metronidazole is still an effective antibiotic against B. fragilis. Viruses are the most important etiological agents of diarrhea in children less than 5 years of age.

  8. Improved Hybrid Genome Assemblies of Two Strains of Bacteroides xylanisolvens, SD_CC_1b and SD_CC_2a, Obtained Using Illumina and 454 Sequencing Technologies

    PubMed Central

    Ramaraj, Thiruvarangan; Sundararajan, Anitha; Schilkey, Faye D.; DelVecchio, Vito G.; Donlon, Mildred; Ziemer, Cherie

    2014-01-01

    Bacteroides xlyanisolvens strains (SD_CC_1b, SD_CC_2a) isolated from human feces were grown on crystalline cellulose. Cellulolytic properties are not common in Bacteroides species. Here, we report improved genome sequences of both of the B. xlyanisolvens strains. PMID:24699955

  9. Improved hybrid genome assemblies of 2 strains of Bacteroides xylanisolvens SD-CC-1b and SD-CC-2a using Illumina and 454 sequencing technologies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteroides xlyanisolvens strains (SD_CC_1b, SD_CC_2a) isolated from human feces were able to grow on crystalline cellulose. Cellulolytic properties are not common in Bacteroides species. Here, we report improved genome sequences of both the B. xlyanisolvens strains....

  10. Isolation and characterization of Bacteroides host strain HB-73 used to detect sewage specific phages in Hawaii.

    PubMed

    Vijayavel, Kannappan; Fujioka, Roger; Ebdon, James; Taylor, Huw

    2010-06-01

    Previous studies have shown that Escherichia coli and enterococci are unreliable indicators of fecal contamination in Hawaii because of their ability to multiply in environmental soils. In this study, the method of detecting Bacteroides phages as specific markers of sewage contamination in Hawaii's recreational waters was evaluated because these sewage specific phages cannot multiply under environmental conditions. Bacteroides hosts (GB-124, GA-17), were recovered from sewage samples in Europe and were reported to be effective in detecting phages from sewage samples obtained in certain geographical areas. However, GB-124 and GA-17 hosts were ineffective in detecting phages from sewage samples obtained in Hawaii. Bacteroides host HB-73 was isolated from a sewage sample in Hawaii, confirmed as a Bacteroides sp. and shown to recover phages from multiple sources of sewage produced in Hawaii at high concentrations (5.2-7.3 x 10(5) PFU/100 mL). These Bacteroides phages were considered as potential markers of sewage because they also survived for three days in fresh stream water and two days in marine water. Water samples from Hawaii's coastal swimming beaches and harbors, which were known to be contaminated with discharges from streams, were shown to contain moderate (20-187 CFU/100 mL) to elevated (173-816 CFU/100 mL) concentrations of enterococci. These same samples contained undetectable levels (<10 PFU/100 mL) of F+ coliphage and Bacteroides phages and provided evidence to suggest that these enterococci may not necessarily be associated with the presence of raw sewage. These results support previous conclusions that discharges from streams are the major sources of enterococci in coastal waters of Hawaii and the most likely source of these enterococci is from environmental soil rather than from sewage. PMID:20451947