Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BACTEROIDES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources
PubMed1985

Evidence that the clindamycin-erythromycin resistance gene of Bacteroides plasmid pBF4 is on a transposable element.

We constructed a shuttle vector, pE5-2, which can replicate in both Bacteroides spp. and Escherichia coli. pE5-2 contains a cryptic Bacteroides plasmid (pB8-51), a 3.8-kilobase (kb) EcoRI-D fragment from the 41-kb Bacteroides fragilis plasmid pBF4, and RSF1010, an IncQ E. coli plasmid. pE5-2 was mobilized by R751, an IncP E. coli plasmid, between E. coli strains with a frequency of 5 X 10(-2) to 3.8 X 10(-1) transconjugants per recipient. R751 also mobilized pE5-2 from E. coli donors to Bacteroides uniformis 0061RT and Bacteroides thetaiotaomicron 5482 with a frequency of 0.9 X 10(-6) to 2.5 X 10(-6). The Bacteroides transconjugants contained only pE5-2 and were resistant to clindamycin and erythromycin. Thus, the gene for clindamycin and erythromycin resistance must be located within the Eco RI-D fragment of BF4. A second recombinant plasmid, pSS-2, which contained 33 kb of pBF4 (including the EcoRI-D fragment and contiguous regions) could also be mobilized by R751 between E. coli strains. In some transconjugants, a 5.5-kb (+/- 0.3 kb) segment of the pBF4 portion of pSS2 was inserted into one of several sites on R751. In some other transconjugants this same 5.5-kb segment was integrated into the E. coli chromosome. This segment could transfer a second time onto R751. Transfer was RecA independent. The transferred segment included the entire EcoRI-D fragment, and thus the clindamycin-erythromycin resistance determinant, from pBF4.

Bacteroides↗
PubMed1990

Detection of conjugal transfer systems in oral, black-pigmented Bacteroides spp.

Oral, black-pigmented Bacteroides spp. are important pathogens in oral anaerobic infections and dental disease. We detected conjugation systems in isolates of Bacteroides denticola and Bacteroides intermedius that transferred tetracycline resistance (Tetr) and penicillin resistance to Bacteroides buccae and to Bacteroides fragilis, an intestinal Bacteroides species. A cloned Tetr gene from B. fragilis hybridized to the transferable Tetr locus in the oral strains, indicating that genetic exchange occurs between these two groups of anaerobes.

Bacteroides↗
PubMed2003

Family of shuttle vectors for ruminal Bacteroides.

A family of shuttle plasmids was constructed for genetic transformation of Escherichia coli and of ruminal Bacteroides strains AR20 and AR29. Plasmids were based on the replicon from Bacteroides plasmid pBI191 and were designed for studies of chromosomal integration (pBA), for the identification and study of Bacteroides gene promoters (pPPR) and for the expression of heterologous genes in Bacteroides (pBAC). Electroporation efficiency of Bacteroides was up to 10(5) transformants/microg plasmid, depending on the source of the DNA. The largest plasmid, pBA, was maintained at approximately 8 copies per cell in AR20 and did not measurably alter in vitro growth of transformed cells. In the current work, pBA did not integrate into the chromosomes of AR20 or AR29. The ability of plasmid pPPR to select promoter sequences was demonstrated by removal and replacement of promoters that activate the clindamycin resistance gene. The suitability of pBAC for expression of heterologous genes was demonstrated by expression of the Moraxella species fluoroacetate dehalogenase gene H1 to give intracellular activity of 7 nmol fluoride released/min/mg soluble protein in AR20 and 4 nmol/min/mg in AR29. Spontaneous loss of pBAC under non-selective conditions was 0.11-0.165% per generation, significantly less than loss of the native Bacteroides plasmid pBI191, which was lost at 0.53% per generation.

Animals↗
PubMed1988

Relationship between enzyme activities involved in oxygen metabolism and oxygen tolerance in black-pigmented Bacteroides.

In this study, the relationship between enzyme activities involved in oxygen metabolism and the degrees of oxygen tolerance in black-pigmented Bacteroides was investigated. All strains of Bacteroides tested possessed the activities of NADH oxidase and superoxide dismutase, whereas the activities of catalase and peroxidases were not detected in the cell-free extracts. There were relatively high correlations between oxygen tolerance and activity of either NADH oxidase or superoxide dismutase. The activity of superoxide dismutase showed a higher correlation with oxygen tolerance than with that of NADH oxidase. Among the species tested, Bacteroides gingivalis showed the highest activities of both the enzymes and was the most tolerant in the presence of oxygen. Furthermore, the activities of these two enzymes increased during aeration of the oxygen-tolerant strain Bacteroides gingivalis 381, but not in the oxygen-sensitive strain Bacteroides denticola ATCC 33185. These results suggest that superoxide dismutase and NADH oxidase might be important for protection of black-pigmented Bacteroides against the toxic effect of oxygen.

Bacteroides↗
PubMed1991

Rapid identification of clinically important bacteroides by coagglutination method.

A coagglutination technique using indigenous reagents was applied for the rapid identification of Bacteroides fragilis and the black pigmented bacteroides group, using colony suspensions. All the 58 strains of B. fragilis and 42 strains of black pigmented bacteroides tested could be correctly identified by this method. The specificity of the coagglutination reagent was confirmed by the absence of cross reactivity with the related species of bacteroides, viz., B. distasonis, B. ovatus, B. vulgatus and B. thetaiotaomicron as well as other anaerobic and aerobic bacteria. A panel of four antisera against B. fragilis was required for correct identification of the strains tested, indicating the presence of multiple serotypes. On the other hand, all 42 strains of black pigmented bacteroides tested could be identified, using a single reagent as these strains appeared to have no antigenic type variants.

Agglutination Tests↗
PubMed2005

Global protein expression pattern of Bradyrhizobium japonicum bacteroids: a prelude to functional proteomics.

As a prelude to using functional proteomics towards understanding the process of symbiotic nitrogen fixation between the legume soybean and the soil bacteria Bradyrhizobium japonicum, we examined the total protein expression pattern of the nodule bacteria, often referred to as bacteroids. A partial proteome map was constructed by separating the total bacteroid proteins using high-resolution 2-DE. Of the several hundred protein spots analyzed using PMF, 180 spots were tentatively identified by searching the available database for B. japonicum, (http://www.kazusa.or.jp/index.html). The data showed that the bacteroid expressed a dominant and elaborate protein network for nitrogen and carbon metabolism, which is closely dependent on the plant supplied metabolites, and seems aptly supported by a selective group of bacteroid transporter proteins. However, they seem to lack a defined fatty acid and nucleic acid metabolism. Interestingly, the proteins related to protein synthesis, scaffolding and degradation were among the most predominant spots of the bacteroid proteome. In addition, several proteins, which showed fairly good expression, were identified to be involved with cellular detoxification, stress regulation and signaling communication components. This preliminary proteomic data matches very well with several biochemical and genetic reports, and clearly shows the inter-connection between several metabolic pathways that meet the needs of the bacteroid. It is expected that in the future this will allow us to develop testable hypotheses about the roles of several of these proteins in context to the metabolic pathway connections and metabolite fluxes.

Amino Acids↗
PubMed1998

Multiple bacteroids in the bacteriome of the lantern bug Pyrops candelaria Linn. (Homoptera: Fulgoridae).

Bacteriome in the lantern bug Pyrops candelaria harbored a-, t-, and companion bacteroids. The a- and t-bacteroids were irregular bodies, whereas the companion bacteroids were rod-shaped and easily distinguished from the others. The a- and t-bacteroids were enveloped by three membranes and the companion bacteroids, by two membranes. The cytoplasm of the a-bacteroid contained electron-dense bodies.

Animals↗
PubMed1990

Periplasmic metabolism of glutamate and aspartate by intact Bradyrhizobium japonicum bacteroids.

In studies on the uptake and metabolism of [14C]glutamate by Bradyrhizobium japonicum bacteroids we found that, in the presence of unlabeled malate, succinate or alpha-ketoglutarate, substantial label was recovered in alpha-ketoglutarate in the reaction mixtures. As much as 30% of the total 14C supplied could be found in alpha-ketoglutarate in the reaction mixtures after 30 min and this occurred in the absence of detectable labeling of alpha-ketoglutarate in the cells. The labeling of alpha-ketoglutarate was almost completely inhibited by aminooxyacetate (aminotransferase inhibitor). Direct assay of aspartate aminotransferase in intact bacteroids was possible in the presence of very dilute Triton X-100 (less than or equal to 0.02%, w/v). The response of the aminotransferase to detergent was similar to the response of phosphodiesterase, a periplasmic marker, and different from malate dehydrogenase and beta-hydroxybutyrate dehydrogenase, cytoplasmic markers. Comparison of maximum enzyme activity assayable with intact bacteroids and maximum activity in sonicated bacteroids indicated that about half of the total cellular aminotransferase activity was accessible to the external medium. The combined labeling and enzyme assay results indicated that B. japonicum bacteroids have a capability for transamination in the periplasmic space. Although this may not be important in the transfer of reducing equivalents from host cytoplasm to bacteroids in nodules, the transamination capability may facilitate the acquisition of metabolites by free-living bacteria.

Anaerobiosis↗
PubMed2002

Relationship between bacteroid poly-beta-hydroxybutyrate accumulation and nodule functioning in the Galega orientalis-Rhizobium galegae symbiosis under diamine treatment.

Exposure of Galega orientalis plants to diamines putrescine (Put) and cadaverine (Cad) at concentrations from 0.01 to 2.0 mM significantly altered carbon and nitrogen metabolism in their root nodules. Correlative studies of bacteroid poly-beta-hydroxybutyrate (PHB) content and acetylene-reduction capacity of the nodules revealed a negative relationship between these parameters. Utilisation of PHB deposits by bacteroids and high acetylene reduction activity was observed when applying low diamine concentrations. The increase in PHB accumulation in response to high diamine levels was accompanied by a considerable decline in nodule nitrogenase activity. Supplying isolated Galega bacteroids with various diamine concentrations significantly modified bacteroid oxygen consumption, which might be associated with alterations in carbon flux to the bacteroids. Finally, modulation of the bacteroid content upon Put and Cad treatment was examined. The results are discussed in terms of possible causes of the diamine-induced changes in nodule metabolism.

Journal Article↗
PubMed1998

Alanine, not ammonia, is excreted from N2-fixing soybean nodule bacteroids.

Symbiotic nitrogen fixation, the process whereby nitrogen-fixing bacteria enter into associations with plants, provides the major source of nitrogen for the biosphere. Nitrogenase, a bacterial enzyme, catalyzes the reduction of atmospheric dinitrogen to ammonium. In rhizobia-leguminous plant symbioses, the current model of nitrogen transfer from the symbiotic form of the bacteria, called a bacteroid, to the plant is that nitrogenase-generated ammonia diffuses across the bacteroid membrane and is assimilated into amino acids outside of the bacteroid. We purified soybean nodule bacteroids by a procedure that removed contaminating plant proteins and found that alanine was the major nitrogen-containing compound excreted. Bacteroids incubated in the presence of 15N2 excreted alanine highly enriched in 15N. The ammonium in these assays neither accumulated significantly nor was enriched in 15N. The results demonstrate that a transport mechanism rather than diffusion functions at this critical step of nitrogen transfer from the bacteroids to the plant host. Alanine may serve only as a transport species, but this would permit physiological separation of the transport of fixed nitrogen from other nitrogen metabolic functions commonly mediated through glutamate.

Journal Article↗
PubMed2006

Overexpression of BetS, a Sinorhizobium meliloti high-affinity betaine transporter, in bacteroids from Medicago sativa nodules sustains nitrogen fixation during early salt stress adaptation.

Sinorhizobium meliloti possesses several betaine transporters to cope with salt stress, and BetS represents a crucial high-affinity glycine and proline betaine uptake system involved in the rapid acquisition of betaines by cells subjected to osmotic upshock. Using a transcriptional lacZ (beta-galactosidase) fusion, we showed that betS is expressed during the establishment of the symbiosis and in mature nitrogen-fixing nodules. However, neither Nod nor Fix phenotypes were impaired in a betS mutant. BetS is functional in isolated bacteroids, and its activity is strongly activated by high osmolarity. In bacteroids from a betS mutant, glycine betaine and proline betaine uptake was reduced by 85 to 65%, indicating that BetS is a major component of the overall betaine uptake activity in bacteroids in response to osmotic stress. Upon betS overexpression (strain UNA349) in free-living cells, glycine betaine transport was 2.3-fold higher than in the wild-type strain. Interestingly, the accumulation of proline betaine, the endogenous betaine synthesized by alfalfa plants, was 41% higher in UNA349 bacteroids from alfalfa plants subjected to 1 week of salinization (0.3 M NaCl) than in wild-type bacteroids. In parallel, a much better maintenance of nitrogen fixation activity was observed in 7-day-salinized plants nodulated with the overexpressing strain than in wild-type nodulated plants. Taken altogether, these results are consistent with the major role of BetS as an emergency system involved in the rapid uptake of betaines in isolated and in planta osmotically stressed bacteroids of S. meliloti.

Adaptation, Physiological↗
PubMed2004

A Rhizobium leguminosarum lipopolysaccharide lipid-A mutant induces nitrogen-fixing nodules with delayed and defective bacteroid formation.

Lipopolysaccharides from pea-nodulating strain Rhizobium leguminosarum by. viciae 3841, as all other members of the family Rhizobiaceae with the possible exception of Azorhizobium caulinodans, contains a very long chain fatty acid; 27-hydroxyoctacosanoic acid (27OHC28:0) in its lipid A region. The exact function and importance of this residue, however, is not known. In this work, a previously constructed mutant, Rhizobium leguminosarum by. viciae 22, deficient in the fatty acid residue, was analyzed for its symbiotic phenotype. While the mutant was able to form nitrogen-fixing nodules, a detailed study of the timing and efficiency of nodulation using light and electron microscopy showed that there was a delay in the onset of nodulation and nodule tissue invasion. Further, microscopy showed that the mutant was unable to differentiate normally forming numerous irregularly shaped bacteroids, that the resultant mature bacteroids were unusually large, and that several bacteroids were frequently enclosed in a single symbiosome membrane, a feature not observed with parent bacteroids. In addition, the mutant nodules were delayed in the onset of nitrogenase production and showed reduced nitrogenase throughout the testing period. These results imply that the lack of 27OHC28:0 in the lipid A in mutant bacteroids results in altered membrane properties that are essential for the development of normal bacteroids.

Bacterial Proteins↗
PubMed1977

Changes in the Number, Viability, and Amino-acid-incorporating Activity of Rhizobium Bacteroids during Lupin Nodule Development.

Between days 10 and 21 after inoculation of Lupinus angustifolius seedlings with Rhizobium NZP 2257, the average nodule fresh weight increased 3-fold and the number of bacteroids per nodule increased more than 10-fold.The viability of Rhizobium bacteroids, as judged by their ability to form colonies on yeast-extract agar, declined from about 10% on days 10 and 11 after inoculation to about 0.3% on days 14 to 25. Bacteroid viability was highly sensitive to osmolarity.At optimal pH and K and Mg ion concentrations, the incorporation of (14)C-glycine into isolated bacteroids was also very sensitive to osmolarity, and fell in parallel with bacteroid viability during nodule development.WE SUGGEST THAT AT LEAST TWO PROCESSES CONTRIBUTE TO BACTEROID NONVIABILITY: a reversible change in the cell wall structure occurring between days 10 and 14 after inoculation, and a subsequent irreversible change.

Journal Article↗
PubMed1977

Heme Synthesis in Soybean Root Nodules: I. On the Role of Bacteroid delta-Aminolevulinic Acid Synthase and delta-Aminolevulinic Acid Dehydrase in the Synthesis of the Heme of Leghemoglobin.

During nodulation of soybean (Glycine max) by Rhizobium japonicum, variations in the activities of two enzymes of heme biosynthesis, delta-aminolevulinic acid synthase (ALAS) and delta-aminolevulinic acid dehydrase (ALAD) are described. delta-Aminolevulinic acid synthase activity is found in the bacteroid fraction of nodules, but is not detected in the plant fraction. Bacteroid ALAS activity parallels heme accumulation during nodule development. delta-Aminolevulinic acid dehydrase activity is found in both bacteroid and plant cytosol fractions. Bacteroid ALAD activity is constant or increases during nodulation while plant ALAD activity falls.Bacteroid ALAD activity is found in effective, not in inefficient nodules. Plant ALAD activity is found in both effective and inefficient nodules. Plant ALAD activity falls during development of both types of root nodules.These results support the contention that it is the bacteroid ALAS and ALAD activities, not those of the plant, that are directly involved in formation of leghemoglobin heme, suggesting that the bacteroid may be solely responsible for formation of leghemoglobin heme in the nodule symbiosis.

Journal Article↗
PubMed1978

Development of Bacteroids in Alfalfa (Medicago sativa) Nodules.

The morphology, acetylene reduction capability, and nucleic acid content of bacteroids in different regions of alfalfa (Medicago sativa var. Buffalo) nodules were studied by electron microscopy, gas chromatography, and laser flow microfluorometry, respectively. Bacteroids in the nodule tips were small (1 to 2.5 micrometers in length), had low nucleic acid content, and contained distinct central nucleoids. These bacteroids were comparatively inactive in acetylene reduction in situ. Bacteroids in the middle regions of alfalfa nodules were greatly enlarged (5 to 7 micrometers in length), had relatively high nucleic acid content, and did not possess central nucleoids. The bacteroids were very active in acetylene reduction. Bacteroids in the basal nodule region also were enlarged and without distinct nucleoid regions, but had relatively low nucleic acid content and low in situ acetylene-reducing activity.

Journal Article↗
PubMed1984

Electron allocation to H+ and N2 by nitrogenase in Rhizobium leguminosarum bacteroids.

Electron allocation to H+ and N2 by nitrogenase in intact Rhizobium leguminosarum bacteroids has been studied. Nitrogenase activity was measured in intact cells with succinate and oxygen substrates. When whole cell nitrogenase activity was inhibited by oxygen-limitation or by the addition of the H+-conducting ionophore carbonylcyanide m-chlorophenylhydrazone, both inducing a low intracellular ATP/ADP ratio, the electron allocation to H+ was favoured over that to N2. When whole cell nitrogenase activity was inhibited by excess oxygen or by the addition of the K+-conducting ionophore valinomycin, both inhibiting electron transport to nitrogenase without affecting the intracellular ATP/ADP ratio, no effect upon the electron allocation to H+ and N2 was observed. The whole cell experiments could be confirmed by experiments with bacteroids treated with hexadecyltrimethylammonium bromide. Nitrogenase is highly active in these preparations with Na2S2O4 and MgATP as substrates. No effect was observed upon electron allocation to H+ and N2 when nitrogenase was inhibited by limitation of reductant (Na2S2O4) or MgATP. Only when nitrogenase was inhibited by MgADP, electron allocation to H+ was favoured. The amount of nitrogenase component 1 and 2 in bacteroids was estimated with protein blotting, followed by an immunological detection. It was found that 17% +/- 3% of total bacteroid protein is component 1 and 12% +/- 2% is component 2. The specific nitrogenase activity of bacteroids treated with hexadecyltrimethylammonium bromide is 178 +/- 62 nmol C2H4 formed X min-1 X mg total protein-1. Despite the high protein concentrations, nitrogenase is not inhibited. With cell-free extracts or with purified nitrogenase components isolated from R. leguminosarum bacteroids, electron allocation to H+ was favoured over that to N2, independently of the mechanism of inhibition. The discrepancies between the whole cell studies and those with isolated enzyme will be discussed with respect to the present mechanism of action of nitrogenase.

Adenosine Diphosphate↗
PubMed1979

Cross-Feeding of Lactate Between Streptococcus lactis and Bacteroides sp. Isolated from Termite Hindguts.

Streptococcus lactis and Bacteroides sp., isolated from hindguts of Reticulitermes flavipes termites, were grown anaerobically in monoculture and coculture. When grown in a glucose medium, S. lactis monoculture produced lactate as the major fermentation product, with small amounts of formate, acetate, ethanol, and CO(2). In coculture, glucose was completely consumed during growth of S. lactis. Lactate, produced by S. lactis, then supported much of the growth of Bacteroides and was fermented to propionate, acetate, and CO(2). Small amounts of succinate were formed during growth of Bacteroides in the coculture, but little change in the formate or ethanol concentration was observed. Monoculture growth of Bacteroides in a tryptone-yeast extract medium revealed that incorporation of 20 to 40 mM lactate increased cell yields and production of organic acids. However, initial lactate concentrations greater than 40 mM suppressed not only growth of Bacteroides but also acidic product formation. Results suggest that cross-feeding of lactate between streptococci and bacteroides constitutes one aspect of the overall hindgut fermentation in termites.

Journal Article↗
PubMed1988

Identification and Characterization of a Bacteroid-Specific Dehydrogenase Complex in Rhizobium leguminosarum PRE.

In membranes of Rhizobium leguminosarum bacteroids isolated from nitrogen-fixing pea root nodules, two different protein complexes with NADH dehydrogenase activity were detected. One of these complexes, with a molecular mass of 110 kilodaltons, was also found in membranes of free-living rhizobia, but the other, with a molecular mass of 550 kilodaltons, appeared to be present only in bacteroids. The bacteroid-specific complex, referred to as DH1, probably consists of at least four different subunits. Using antibodies raised against the separate polypeptides, we found that a 35,000-molecular-weight polypeptide (35K polypeptide) in the DH1 complex is bacteroid specific, while the other proposed subunits were also detectable in cytoplasmic membranes of free-living bacteria. Dehydrogenase complex DH1 is also present in bacteroids of a R. leguminosarum nifA mutant, indicating that the synthesis of the dehydrogenase is not dependent on the gene product of this nif-regulatory gene. A possible involvement of the bacteroid-specific DH1 complex in electron transport to nitrogenase is discussed.

Journal Article↗